3GPP TSG RAN WG1 #120bis                                                            R1-2501818
WuHan, China, April 7th – 11st, 2025

Source:	vivo, BUPT
Title:	Views on Rel-19 ISAC channel modelling
Agenda Item:	9.7.2
Document for:	Discussion and Decision

Conclusions
In this contribution, we have studied the target channel modeling, including the realization of concatenation in the target channel modeling, including the RCS modeling, and EO modeling, channel model formation, including two component channel modeling, as well as the enhancements of Doppler, spatial consistency as additional modelling components, and link-level based channel model for ISAC. The observations and proposals are summarized as follows.
Observation 1: From the experiment measurements, there are three peaks in the incident (back scattering), specular scattering and other scattering (e.g., forward scattering) angles, observed over the angular ranges of  [0⁰,360⁰] and  [0⁰,180⁰].
Observation 2: In case that the specular phenomenon occurs, the amplitude gap between LOS path and specular paths is about 10dB, while the gap between the specular paths and non-specular paths is about 5dB.
Observation 3: There is no impact by introducing the specular reflection model when the orientation and the finite size of EO is taken into account.
Observation 4: The system performance is not greatly affected if the target channel is directly summated into the background channel without power normalization.
Observation 5: If assuming the azimuth angle  of the center point  and the elevation angle  of the scatterer P can be set to zero, i.e.,  and  the micro-Doppler frequency shift induced by the vibration of a scatterer point can be derived by Eq. 8.
Observation 6: The micro-Doppler frequency shift induced by the human arm/leg vibration can be calculated by either the instantaneous amplitude or the average amplitude.
Observation 7: The moving direction of human and frequency bands influence the micro-Doppler:
When the human body with the moving direction is facing the transmit and receive antennas, the sinusoidal function fluctuations due to the micro-Doppler are obvious, for all the six cases.
When the human body with the moving direction is perpendicular to the transmit and receive antennas, the sinusoidal function fluctuations due to the micro-Doppler are not that obvious, for all the six cases.
Micro-Doppler behavior for arm periodic swing is more obvious than that for leg periodic swing.
Different frequency bands influence micro-Doppler differently, i.e., the higher the frequency band, the more influence on micro-Doppler.
Observation 8: The agreement between the formula of micro-Doppler frequency  and the experiment results is very well.
Observation 9: There are at least the following issues related to the spatial consistency of ISAC:
Issue1: Which sensing mode among six sensing modes should be considered?
Issue2: Whether single and/or multiple targets channels, and/or background channels need to be considered?
Issue3: How spatial consistency in sensing channel can be modelled?
Observation 10: The correlation of grids associated with different targets can be modelled by the proposed target-specific method.
Observation 11: The proposed target-specific method can be extended to 3D to support the 3D spatial consistency for some ISAC scenarios, e.g., UAV.
Observation 12: For single target channels, both the proposed target-specific method and the site-specific method defined in TR38.901 can guarantee the spatial consistency among channels.
Observation 13: For multiple targets channels, the proposed target-specific method can guarantee the spatial consistency among channels. However, the site-specific method defined in TR38.901 cannot guarantee the spatial consistency among channels, e.g., the correlation of AOA angle.
Observation 14: Reducing the size of grid for target-specific method can significantly reduce the memory overhead and time overhead.
Observation 15: For single target channels, the proposed simplified target-specific method with Option2 and Alt2/Alt3 can guarantee the spatial consistency among channels.
Observation 16: For multiple targets channels, the proposed simplified target-specific method with Option2 and Alt3 can guarantee the spatial consistency among channels. While, Alt2 cannot guarantee the spatial consistency among channels, e.g., the correlation of AOA angle.
Observation 17: Due to interpolation based on relative location in Option1, the correlation modeled by Option1 may be inconsistent with the reality.
Observation 18: UT specific grid and ST specific grid are essentially the same method. However, the complexity of the UT specific grid is usually higher because of the higher configured number of UTs in simulation evaluation.

Proposal 1: The bi-static and mono-static RCS model share the same mathematical model at least for small UAV and human.
Proposal 2: RAN1 models the bi-static RCS associated with each incident angle by independently considering multiple bi-static RCS components, for different use case target.
Proposal 3: To calculate  for bi-static RCS in the direction of back-scattering and ensure a consistency between mono-static RCS and bi-static RCS at the incident angle, RAN1 reuses the same formula (Eq. 1) and the same parameters as defined for mono-static RCS.
Proposal 4: To calculate  for bi-static RCS in the direction of specular-scattering, RAN1 considers the same formula (Eq. 1) but with different parameter table as listed Table 2.
Proposal 5: If the other scattering impact is considered for bi-static RCS, RAN1 independently defines bi-static RCS component in the other-scattering.
Proposal 6: To combine all the bi-static RCS components, select the bi-static RCS component with the maximum RCS value.
Proposal 7: In the multi-point RCS model, the UAV is divided into 5 scatter points, i.e., airframe body and four airfoils.
Proposal 8: In the multi-point RCS model, the human is divided into 6 scatter points, i.e., head, abdomen, two legs and two hands.
Proposal 9: Whether the location of scatter point of the sensing target changes is dependent on the specific use cases.
Proposal 10: The RCS value of the entire target is the linear summation of the RCSs from the segmented parts of the entire target.
Proposal 11: The region of two legs or two hands can be modelled by the same RCS.
Proposal 12: The region of four airfoils of UAV can be modelled by the same RCS.
Proposal 13: RAN1 utilizes the mechanism of spatial consistency to ensure the channel correlation among different scatter points in the same target.
Proposal 14: The formula of the normalization factor as expressed below can be utilized for CPM normalization after CPM concatenation,

where the , ,  and  are the random coefficients after CPM concatenation.
Proposal 15: RAN1 determines whether the power normalization of CPM is necessary after CPM concatenation depends on the value of XPR for CPM of target.
Proposal 16: For type-2 EO, the indoor and the urban grid scenario are prioritized for the type-2 EO modelling.
Proposal 17: The detailed EO modelling can be done after the target modelling is consolidated.
Proposal 18: RAN1 reuses the parameters of , , and  without any updating.
Proposal 19: Power normalization is not required in the channel combination procedure.
Proposal 20: The combination of directly summation without power normalization can be applied to the all the scenario or sensing mode as a simple implementation.
Proposal 21: RAN1 should consider reducing the ISAC channel model complexity by reducing the number of clusters for TX-target and target-RX link in target channel.
Proposal 22: RAN1 agrees on the formula of micro-Doppler frequency shift in Eq. 8 or Eq. 9 at least for the human arm/leg target with the vibration of a scatterer point and the mono-static transmitter/receiver.
Proposal 23: RAN1 studies the formula of micro-Doppler at least for human target, and Eq. 8 or Eq. 9 can be a starting point.
Proposal 24: RAN1 studies the spatial consistency for all six sensing modes.
Proposal 25: RAN1 studies the spatial consistency for all single target channels, multiple targets channels and background channels.
Proposal 26: The correlation of grids associated with different targets needs to be modelled.
Proposal 27: The 3D spatial consistency needs to be supported for some ISAC scenarios, e.g., UAV.
Proposal 28: Using the proposed target-specific method to model the spatial consistency of single/multiple targets channels with Cell-to-UE bi-static sensing mode.
Proposal 29: Using the proposed target-specific method to model the spatial consistency of target(s) channels with Cell-to-Cell bi-static, Cell mono-static, Cell-to-UE bi static, UE-to-Cell bi-static, UE-to-UE bi-static and UE mono-static sensing mode.
Proposal 30: Target-specific method can be replaced by UE-specific method, i.e., use the same procedures to generate correlated grid associated with each UE, instead of the target.
If using UE-specific method, only the spatial consistency of target(s) channels with Cell-to-UE bi static, UE-to-Cell bi-static, UE-to-UE bi-static and UE mono-static sensing mode can be modelled.
Proposal 31: For background channels, RAN1 uses the site-specific method defined in TR38.901 to model the spatial consistency for random clutters, and there is no need to model spatial consistency for EO-type2.
Proposal 32: The complexity reduction of target-specific method can be considered, e.g., by reducing the size of grid and using the combination of interpolation and extrapolation.
Proposal 33: The stochastic link level channel model based on TR38.901 should be considered as a starting point in the ISAC.
Proposal 34: RAN1 further studies the stochastic link level channel model for ISAC by adding sensing target cluster based on CDL channel model defined in TR38.901.

3GPP TSG RAN WG1 Meeting #120b	          	     	                                               R1-2501840
Wuhan, China, April 7th – 11th, 2025
Agenda Item:	9.7.2
Source: 	EURECOM
Title: 	Discussion on ISAC channel modeling
Document for:	Discussion and decision

Conclusions
In this contribution, the following proposals are put forward:
Proposal 1: The channel is developed based on Geometry-based stochastic channel model TR 38.901. The parameters need to be updated for the channel model of TRP-TRP link and UE-UE link.
Proposal 2: The number of scattering points depend on the size of the targets, type of channel as well the distance between the sensing target. 
Proposal 3: AGV is modelled with 5 scattering points. RCS option 3 is used to model RCS of a scattering point of AGV for monostatic. A is mean RCS value. B2 is modelled using log-normal distribution. For small AGV, B1 is equal to 1. For large AGV, B1 has dependency on incident/scattered angles so B1 is different to 0 dB. B2 is modelled by a Gaussian distribution (, ) with .
Proposal 4: RCS option 2 or RCS option 3 with B1 equal to 1 is used to model RCS of animals. In both options, A is mean RCS value. If Option 2 is used, B is modelled using log-normal distribution. If Option 3 is used, B2 is modelled using log-normal distribution.
Proposal 5: The small-scale parameters for the sensing channel such as RCS, echo angles, cross power ratio are generated after the general parameters are generated. Subsequently, channel coefficient for the sensing channel is generated then pathloss is calculated for each sensing cluster.
Proposal 6: Both NLOS and LOS rays are generated for the Tx-target and target-Rx links if LOS condition is determined.
Proposal 7: There are maximum two bounces between Tx and Rx.
Proposal 8: EO type 1 is not modelled in the propagation path Tx-target-Rx.
Proposal 9: A propagation path with more than one sensing target is not modelled.
Proposal 10: When an EO type 2 blocks a LOS path in a one link, that link is considered as NLOS path. Otherwise, LOS probability is calculated as in TR 38.901, 37.885.
Proposal 11: The target channel is modelled with Tx-target-Rx rays, Tx-target-EO type2/stochastic clutter-Rx rays, Tx- EO type 2/stochastic clutter- target -Rx rays.
Proposal 12: The number of clusters between the Tx and the Rx is the same as number of clusters in TR 38.901. The clusters are divided in two types LOS cluster and NLOS cluster where each NLOS cluster includes 20 rays as in TR 38.901. The number of rays in a cluster is the same as in the current TR.
Proposal 13: In power scaling factor equation, if an object is modelled by multiple scattering points, RCS component A of the object is the average value of RCS components A of all scattering points.
Proposal 14: EO-Type 2 can be modeled in background channel.
Proposal 15: Background channel with pathloss, LOS probability modelled with both EOs and stochastic clutters is generated from the channel model in TR 38.901.
Proposal 16: Power normalization is not carried out on both target channel and background channel when target channel and background channel are combined.
Proposal 17: if the Tx and Rx are static, the mobility model in TR 38.901 is used.
Proposal 18: a micro-Doppler model is not necessary to model the frequency shift.
Proposal 19: For TRP-UE bistatic, UE-TRP bistatic, UE-UE bistatic, UE monostatic, if the UE is static when it is the Tx or Rx, new spatial consistent procedures need to be studied.
Proposal 20: Extends the 2D spatial consistent procedures to support 3D spatial consistency in some scenarios such as UAV.

3GPP TSG RAN WG1 #120bis		                                        R1-2501878
Wuhan, China, April 7th – 11th, 2025

Agenda Item:     9.7.2
Source:	Spreadtrum, UNISOC
Title:	             Discussion on ISAC channel modelling
Document for:	Discussion and decision

Conclusion
In this contribution, we provided our views on the details of the ISAC channel modelling. The following proposals are made:
Proposal 1: When the EO type-2 is used to model the Tx-target link and target-Rx link in the target channel, option A is preferred.
Proposal 2: For spatially-consistent UT/BS/Targets mobility modelling, enhancements on Procedure A is preferred.
Proposal 3: Global grid (aka. Unified grid) + shifting UT/ST locations is preferred to model the correlation of links between two nodes of STs and UTs.

3GPP TSG RAN WG1 #120bis 		                                    		   R1-2501927
Wuhan, China, April 4th -11th, 2025 

Agenda Item:	9.7.2
Source:	InterDigital, Inc.
Title:	Discussion on ISAC channel modeling
Document for:	Discussion and Decision

Conclusion
RCS modelling
Observation 1: For multipoint target modelling, spread of arriving rays associated with the sensing target decreases as we increase Tx-target-Rx distance.  
Proposal 1: At least the distance between the sensing target and sensing Tx/Rx determines whether segmentation-based (multi-point scatter) or single-point modelling should be applied to the sensing target.
Proposal 2: Support angular dependencies for human RCS model 2 in both azimuth and zenith angles 
Observation 2: Details of human body characteristics such as size, posture, and attire affect measurements results
Proposal 3: For human RCS model 2, indicate whether the derived RCS includes the effect of ground reflection or not.
Spatial consistency
Proposal 4: Initial random phase and XPR of  and  are link-correlated for spatial consistency modeling and spatially consistent mobility modeling of the same target.
Proposal 5: Initial random phase and XPR of  is link-correlated for spatially consistent mobility modeling of the same target only.
Channel modelling methodology
Proposal 6: Support stochastic ISAC channel modelling as baseline and focus on characterizing the Tx-Target-Rx link.
Proposal 7: Work on stochastic ISAC channel models is prioritized over Ray-tracing or map-based ISAC channel modelling where the latter should be studied only if time permits 
Background channel
Proposal 8: Regarding combination of target and background channel, support Option 2 Alt1 “Power normalization on both target channel and background channel”

Proposal 9: Adopt a scaling parameter which defines a relative power difference between the background channel and target channel
Determination of LOS/NLOS condition in the presence of EO type-2
Proposal 10: When the EO type-2 is modeled in the target channel, adopt Option B, “Use the LOS probability equation to determine the LOS/NLOS condition of one link, and then the impacts of type-2 EO is modeled by a blockage model”
Proposal 11: An unintended target is a blockage factor in the target channel and further study whether Blockage model A or Blockage model B should be implemented
Details related to concatenation of Tx-target and target-Rx links
Observation 3: For option 0 to generate indirect paths of NLOS ray+ NLOS ray in the target channel, we need to normalize ray power by number of rays per cluster(M). 
Proposal 12: Normalize rays in Option 0 by a scaling factor (e.g.,   where M is the number of rays in target-Rx link) to avoid power inflation through concatenation 
Observation 4: Nearly 40% and 3% of paths are dropped with the path dropping threshold of -25dB and -50dB, respectively.
Proposal 13: Do not adopt path dropping after concatenation
Channel modelling for UAV-target to UAV-UE (aerial)
Proposal 14: Reuse UMi-AV, UMa-AV and RMa-AV scenarios of TRP to aerial UE channel model defined in TR 36.777 for channel between a normal UE and an aerial UE as a starting point.
Proposal 15: Capture the same TRs as case 7 for case 9 to model the channel between two aerial UEs as a starting point.
Modelling micro-Doppler characteristics
Proposal 16: Adopt micro-Doppler functions for humans and UAVs provided in Table 2.
Table 2 Micro-Doppler functions for micro-motions of humans and UAVs
Sensing Area
Proposal 17: Define a sensing coverage area for the ISAC channel model where the area includes only possible points for which the UE or network can localize an object within a specific accuracy requirement. 

3GPP TSG-RAN WG1 Meeting #120-bis	R1- 2501933
Wuhan, China, April 7th – April 11th, 2025

Agenda Item:	9.7.2
Source:	NVIDIA
Title:	Channel modelling for integrated sensing and communication with NR
Document for:	Discussion
1	

Conclusion
In the previous sections, we discuss general aspects of channel modelling for ISAC and make the following observations:
Observation 1: Wireless channel modelling needs to provide consistency and, above all, a correct representation of the frequency, spatial, and temporal correlations across base stations, devices, and objects in the environment.
Observation 2: Deterministic, physics-based modelling for wireless propagation, especially ray tracing, are essential for studying, evaluating, and developing key technologies in 5G-Advanced toward 6G, including ISAC, RIS, larger antenna arrays in new spectrum such as 7-24 GHz and sub-THz bands, AI/ML, etc.
Observation 3: WLAN sensing Task Group IEEE 802.11bf has embraced ray tracing based channel model for WiFi sensing.
Observation 4: Though ray tracing has been considered in the map-based hybrid channel model in TR 38.901, the map-based hybrid model defined is not calibrated and has not been used in 3GPP simulation campaigns.
Observation 5: A common reference scenario defined for ray tracing not only can be used for ISAC evaluation but also for other key technologies toward 6G, including RIS, larger antenna arrays in new spectrum such as 7-24 GHz and sub-THz bands, AI/ML, to name a few.
Based on the discussion in the previous sections we propose the following:
Proposal 1: Even in geometry-based stochastic channel model, the sensing targets need to be modelled in a deterministic manner.
Proposal 2: In geometry‐based stochastic channel model, rays can be traced deterministically from the sensing transmitter to the sensing target and then to the sensing receiver, by modelling different types of interactions between the rays and surrounding objects such as reflections, diffractions and diffuse scatterings.
Proposal 3: In geometry‐based stochastic channel model, the LOS and NLOS conditions between Tx/Rx and sensing target should be deterministically determined based on geometrical locations of environment objects.
Proposal 4: In geometry‐based stochastic channel model, for modelling the target channel of a target with multiple scattering points, a LOS ray from Tx to each scattering point of the target and a LOS ray from each scattering point of the target to Rx are deterministically generated as follows.
For the i-th scattering point of the target, (AoA)_i/(ZoA)_i of the direct path at Rx, and (AoD)_i/(ZoD)_i of the direct path at the target are deterministically generated based on the locations of the i-th scattering point of the target and Rx. 
For the i-th scattering point of the target, (AoD)_i/(ZoD)_i of the direct path at Tx, and (AoA)_i/(ZoA)_i of the direct path at the target are deterministically generated based on the locations of Tx and the i-th scattering point of the target. 
The delay of the direct path associated with the i-th scattering point is deterministically generated as (d3D_tx_target_i + d3D_target_rx_i)/c.
The doppler of the direct path associated with the i-th scattering point of the target is deterministically generated by spherical unit vectors associated with (AoD)_i/(ZoD)_i at Tx, spherical unit vectors associated with (AoA)_i/(ZoA)_i at Rx, and velocities of Tx, i-th scattering point of the target and Rx. 
The power of the direct path associated with the i-th scattering point of the target is generated as the product of the power of the LOS ray from Tx to the i-th scattering point of the target, the power of the LOS ray from the i-th scattering point of the target to Rx, and the effect of RCS.
Proposal 5: In geometry‐based stochastic channel model, the first component of RCS (A*B1*B2) related coefficient of a scattering point should be modelled as follows:
The first RCS component A () should be modelled deterministically and is dependent on incident and scattered directions at target. 
Proposal 6: In geometry‐based stochastic channel model, when blockage or forward scattering between sensing targets is considered, a propagation path from Tx to Rx interacting with more than one sensing target should be modelled.
Proposal 7: In geometry‐based stochastic channel model, blockage and forward scattering between sensing targets should be modelled in the target channel.

Proposal 8: In geometry‐based stochastic channel model, environment objects are deterministically modelled in the ISAC channel.
Proposal 9: In geometry‐based stochastic channel model, environment objects (EO type-1) that share similar physical characteristics as a sensing target are deterministically modelled in the ISAC channel.
Proposal 10: In geometry‐based stochastic channel model, environment objects (EO type-2) that have large sizes, including building walls and ground, are deterministically modelled in the ISAC channel.
Proposal 11: In geometry‐based stochastic channel model, diffraction and scattering can be considered in addition to specular reflection for environment objects (EO type-2) in direct path.
Proposal 12: In geometry‐based stochastic channel model, spatial consistency should be considered for modelling environment objects based on the deterministic locations and movement (if any) of the environment objects.
Proposal 13: In geometry‐based stochastic channel model, define material properties for the buildings and the ground in the urban grid V2X scenario, by using Table 7.6.8-1 in TR 38.901 as a starting point.
Proposal 14: In geometry‐based stochastic channel model, deterministically model ground reflection in the ISAC channel modelling by using the explicit ground reflection model in Section 7.6.8 in TR 38.901 as a starting point.
Proposal 15: In geometry‐based stochastic channel model, deterministically model building wall reflection in the ISAC channel modelling by modifying the explicit ground reflection model in Section 7.6.8 in TR 38.901.
Proposal 16: Ray tracing based channel modelling should be investigated for ISAC. 
Proposal 17: Define a common reference scenario for ray tracing to be used in ISAC evaluation. 
Proposal 18: Select one the following options to define a common reference scenario for ray tracing to be used in ISAC evaluation:
Option 1: Real-scenario map that is a virtual representation of a real area on earth. 
Option 2: Synthetic-scenario map that is artificially constructed to mimic a certain environment such as urban macro, rural macro, indoor office, or indoor factory.
Proposal 19: Describe the scene geometry and the characteristics of the materials involved in the common reference scenario for ray tracing to be used in ISAC evaluation.
Proposal 20: Consider using the existing scenarios defined by METIS as a starting point for discussion.
Proposal 21: Consider the METIS indoor office scenario (including its scene description and material properties) as a reference scenario for ray tracing and map-based hybrid model defined in TR 38.901.
Proposal 22: Describe a reference indoor office scenario for ray tracing in TR 38.901 as follows.
Lengths and widths of the room, cubicles, and tables are given by the figure below:

Heights of the room, cubicles, and tables are 2.9 m, 1.5 m, 0.7 m, respectively.
Materials of the room, cubicles, and tables are concrete, wood, and wood, respectively.
Proposal 23: Update Table 7.6.8-1 on material properties based on the updated version of the ITU recommendation, i.e., ITU-R P.2040-3.
Proposal 24: For the urban grid defined for V2X in TR 37.885, the scene geometry can be described by including assumption on building height, and assumptions on the materials for the buildings and roads can be included.
Building height: 24m
Building material: Concrete
Ground material: Medium dry ground

3GPP TSG RAN WG1 #120bis		R1-2502003
Wuhan, China, April 7th – 11th, 2025

Source:	CATT, CICTCI
Title:	Discussion on ISAC channel modelling
Agenda Item:	9.7.2
Document for:	Discussion and Decision

Conclusion
In this contribution, we discuss the details related to channel modelling methodology. We have the following observation and proposals:
Only LOS condition is considered when modelling ground reflection in TR 38.901. Whether/how to model the impact of deterministic reflection in NLOS condition is absent in legacy TRs.
TRP-UAV channel defined in TR 36.777 is used to model the channel between UAV and cellular UE.
For highway and urban grid scenario,
Channel model between a UE and a RSU and between two UE-type RSUs reuse the V2V channel model with antenna height at RSU changed to 5m, as defined in TR 37.885.
Channel model between a TRP and a RSU should reuse the B2R link modelling in TR 37.885.
Support simplified Option B, i.e. using the existing LOS probability equations in TRs without any blockage model.
A multiplier related to bistatic angle is enough to complete the conversion between bistatic and monostatic RCS, such as min{, RCS_MIN}.
By default, B2 of RCS remains unchanged even if target position changes during simulation. If spatial consistency is considered, B2 of RCS may be further added in the correlation parameter list. 
By default, initial random phase of target CPM remains unchanged even if target position changes during simulation. If spatial consistency is considered, initial random phase of target CPM may be further added in the correlation parameter list.
The base station rotation procedure for CPM of target is not necessary because the XPR and random phase are generated statistically.
An invisible scattering point from an incident or scattered direction is modelled by angular dependent RCS component B1 at the target.
It is recommended to use Rule 1 to determine the power threshold X for path dropping. 
Rule 1: Taking the RMS DS  and RMS AS without path dropping as baseline, the relative loss of RMS DS  with path dropping and the loss of  RMS AS  with path dropping are both less than a given threshold. For example, the mean relative error (MRE) of RMS DS  is 5% and MRE of RMS AS  is 5%.
The scaling factors in step 6 also apply to the scaling factor  and  in step 7 in section 7.5, TR 38.901, where the scaling factors need not be changed after cluster elimination in step 6 in section 7.5.
For the step of removing clusters before channel concatenation, whether the maximum cluster power includes the power of the single LOS ray should be clarified.
The set of indirect paths generated by Option 3 is not updated during movement of Tx, target or Rx, within a given distance D = min{1m, d_3D_min /10}, where d_3D_min is the minimum 3D distances between pairs of Tx/Rx and sensing target. 
The set of remaining indirect paths after path dropping after concatenation is not updated during movement of Tx, target or Rx, within a given distance D = min{1m, d_3D_min /10}, where d_3D_min is the minimum 3D distances between pairs of Tx/Rx and sensing target.
No power normalization of NLOS+NLOS indirect paths before path dropping for Option 3.
For the Mono-static target channel modelling, the determination of delay, angle, K factor and polarization matrix for Tx-target link and target-Rx link should follow the following rules:
Same K factor should be used for two separate links.
LOS AOA and LOS ZOA of target-Rx link should be the same as LOS AOD and LOS ZOD of Tx-target link.
LOS AOD and LOS ZOD of target-Rx link should be the same as LOS AOA and LOS ZOA of Tx-target link.
Delay spread, angle spread and polarization for the two separate links should be generated independently.
The ASA and ZSA of target-Rx link should obey the same statistical distribution characteristics of ASD and ZSD of Tx-target link, respectively.
The ASD and ZSD of target-Rx link should obey the same statistical distribution characteristics of ASA and ZSA of Tx-target link, respectively.
When the sensing Tx and sensing Rx are of the same type in Bi-static mode,
The ASA and ZSA of target-Rx link should obey the same statistical distribution characteristics of ASD and ZSD of Tx-target link, respectively.
The ASD and ZSD of target-Rx link should obey the same statistical distribution characteristics of ASA and ZSA of Tx-target link, respectively.
When EO type-2 is modelled in the case that LOS condition is determined for Tx-Target link or Target-Rx link the impact of EO type-2 on pathloss can be implemented by adding a scaling factor when generating channel coefficients. Modification of the pathloss formula is not needed.
If EO type-2 is modelled when NLOS condition is determined for Tx-Target link or Target-Rx link:
The pathloss of Tx-Target link or Target-Rx link in NLOS condition with EO type-2 is calculated based on the LOS condition pathloss model.
The channel impulse response equation of Tx-Target link or Target-Rx link in NLOS condition with EO type-2 should be modified as following:

Update the agreement for power threshold for background channel in RAN1#120.
For background channel
The power threshold for removing clusters in step 6 in section 7.5, TR 38.901, i.e., [-25 dB] is reused to generated the background channel. 
FFS: whether to add additional very low power clusters
FFS: The reference power for removing cluster is the min (max. Tx-target link cluster power, max. target-Rx link cluster power)
If Option 2 is adopted, alternative 1 is preferred: Power normalization on both target channel and background channel.
The existing spatial consistency model in TR 38.901 (i.e., site-specific correlation) is reused to model correlation of links between one RSU and different STs/UEs, instead of using the newly defined link correlation.
Support Option 1: Generating global grid first, and obtaining either UE-specific or ST-specific grid by shifting the UT/ST locations.

3GPP TSG RAN WG1 #120bis			R1-2502030
Wuhan, China, April 7th – 11th, 2025

Agenda item:		9.7.2
Source:	China Telecom
Title:	Discussion on ISAC channel modelling
Document for:		Discussion

Conclusions
In this contribution, we discuss ISAC channel modelling related issues and have following proposals:
Proposal 1: For A*B1 of RCS for a scattering point of a target bistatic sensing, support bistatic RCS to be constructed into multiple angular regions according to scattered angles.
Proposal 2: For A*B1 of RCS for a scattering point of a target bistatic sensing, adopt the formula , at least for the pseudo-monostatic RSC region, where  is bistatic angle. 
Proposal 3: When the EO type-2 is modelled in the target channel, to determine the LOS condition of the Tx-target link and target-Rx link 
If type-2 EO is in the LOS ray of one link, the link is determined as NLOS condition, otherwise use the LOS probability equation to determine the LOS/NLOS condition.
Proposal 4: Support Option 2-Alt 1 to generate the combined ISAC channel.

3GPP TSG-RAN WG1 Meeting #120bis	R1-2502052
Wuhan, China, April 7th – 11st, 2025

Agenda item:		9.7.2
Source:	Nokia, Nokia Shanghai Bell
Title:	Discussion on ISAC channel modeling
WI code:	FS_Sensing_NR
Release:	Rel-19
Document for:		Discussion and Decision

Conclusions
In this contribution, we are making these proposals for ISAC channel modelling:
Proposal 1: Consider RCS values in Table 8 for target types of mid-size UAV and AGV.
Table 8    RCS Values of mid-size UAV, Robotic Arm, and AGV

Proposal 2: The number of scattering points of one target is dependent on at least target types, deployment scenarios/use cases, and distance/size/shape of the target.
Proposal 3: For bistatic RCS, use the bistatic angle to define at least two angular regions.
Proposal 4: When bistatic angle , the bistatic RCS , at least , where  is monostatic RCS value.
Proposal 5: When  is close to 180 degree, further study how to model bistatic RCS with forward scattering links.
Proposal 6: System-level simulations shall be applied to ensure that complexity reduction scheme of Option 3 maintain similar ISAC channel modeling performance of Option 0.
Proposal 7: Reuse the TR 38.901 log-normal distribution parameters for cross polarization power ratio  of a scattering point of a target as the default values, for the log-normal distribution modeling of XPR ratio.
Proposal 8:  Support Option A: if type-2 EO is in the LOS ray of one link, the link is determined as NLOS condition, and otherwise use the LOS probability equation to determine the LOS/NLOS condition.
Proposal 9:  In indoor scenarios, a limited number of walls, ceilings and floor may be modeled with as EO-type 2. 
Proposal 10:  In outdoor scenarios, EO type 2 objects are limited to ground bounce model specified in Section 7.6.8 of TR38.901.
Proposal 11:  For targets with multiple scattering points, the micro-Doppler modeling shall be based on the dual mobility modeling of Section 7.6.10 of TR38.901 as baseline.
Proposal 12: For the monostatic background channel modelling, the LOS pathloss of one reference point with distance  shall be

where  is a reflection coefficient of modelling clutter.
Proposal 13: The background arrivals shall be modelled as collection of scattering power of clusters, each which is uniformly distributed in a delay-azimuth-elevation grid.
Proposal 14: The size of delay-azimuth-elevation grid is configurable, depending on scenarios and simulation resources.
Proposal 15: The background scattering power of one scattering cluster in one grid cell is

where  is pathloss,  is clutter map with a lognormal distribution function,  is delay spread from 38.901 for corresponding scenario, and  is a step function.

3GPP TSG RAN WG1 #120-bis		R1- 2502055
Wuhan, China, April 7th – 11th, 2025

Source:	Tiami Networks
Title:	Discussion on ISAC channel modeling
Agenda Item:	9.7.2
Document for:	Discussion and Decision

Conclusion

Proposal 1: RAN1 should consider ray-level full convolution (Option 0) for NLOS+NLOS paths in target channels, with 1-by-1 ray coupling (Option 3) and power threshold level-based path dropping to reduce complexity. Power normalization should be applied after the concatenation. 

Proposal 2: An RCS modeling framework should be developed that ensures consistency between monostatic and bistatic sensing modes across diverse target types, including dynamic multi-scattering-point targets like vehicles or AGVs. 

Proposa1 3: For targets with multiple scattering points such as car and human, determine a distance threshold to determine the number of scattering points i.e., single or multiple scattering points. 
Proposal 4: Consider spatial consistency or intra-target correlation models for multiple scattering points of a single target. 

Proposal 5: Consider generating very low energy clusters for the background channel to incorporate channels with energy levels comparable to the target channel power. To keep the complexity low, adding single ray clusters is recommended. 

Proposal 6: Limit spatial consistency modeling to LOS state and shadow fading for the target channel, treating NLOS parameters as uncorrelated to reduce complexity without sacrificing sensing accuracy.

3GPP TSG RAN WG1 #120bis		 	      R1-2502063
Wuhan, China, April 07th – 11st, 2025

Source:           ZTE Corporation, Sanechips, OPPO, BUPT, BJTU, CAICT, Xiaomi
Title:             Joint views on mono-static background channel modeling  
Agenda item:      9.7.2
Document for:     Discussion

Conclusion 
In this contribution, we provide our measurements, RT simulations, and analysis on background channel of mono-static sensing, and we have the following proposals:
Proposal 1: Confirm the previous working assumption on background channel for mono-static sensing with the following details:
reference points are dropped for one Tx, based on the Gamma distribution for distance and height of reference point.
The LOS AOD between Tx and the first reference point is generated based on uniform distribution , and the gap of LOS AOD between the Tx and different reference points keeps as .
The background channel is generated based on the channel generated as in existing TR between the real Tx and the reference point in NLOS condition.
The antenna field pattern and array orientation of reference point are set same as Tx. 
Arrival angles for both azimuth and elevation  and  are set equal to departure angles, and coupled with the corresponding departure angles one by one.
The mono-static background channel for the Tx would be sum of channels of the links between the Tx and all related reference points, which is


Proposal 2: For background channel of mono-static sensing, the distance between Tx and the reference point, and the height of the reference point follow parameterized Gamma distribution  with offset , and the related parameters in scenarios of UMa, UMi, RMa, Urban grid, Indoor-office, and highway are given by:

3GPP TSG RAN WG1 #120bis			                              R1-2502171
Wuhan, China, April 7th – 11th, 2025

Agenda item:	9.7.2
Title:	Discussion on channel modelling methodology for ISAC
Source:	CMCC, BUPT, SEU, PML
Document for:	Discussion and Decision

Conclusion
In this contribution, we provide our views on ISAC channel modelling, and the following observations and proposals are made:
Observation 1: The CPM (in dB unit) of vehicle follows .
Observation 2: The CPM (in dB unit) of large UAV follows .
Observation 3: The CPM (in dB unit) of small UAV follows .
Observation 4: There's a clear difference between the CPM distributions of monostatic and bistatic modes.

Proposal 1: The CPM model at monostatic mode should be type dependent. The model should relax the requirements for size and frequency. 
Proposal 2: The CPM model should be concluded from the simulation or measurement data.
Proposal 3: The generated CPM data should have a value limitation. 
Proposal 4: The RCS of small UAV can be model by lognormal distribution.
Proposal 5: It’s not necessary to model the frequency dependency of the small UAV RCS.

3GPP TSG-RAN WG1 Meeting #120bis	   R1-2502208
Wuhan, China, April 7-11, 2025

Agenda Item:	9.7.2
Source:	Huawei, HiSilicon
Title:	Channel modelling for ISAC 
Document for:	Discussion and Decision

Conclusions
In this contribution, we discussed the bi-static RCS modelling for vehicle and provide the bi-static RCS values for vehicle, the mono-static RCS values for AGV and mono/bi-static RCS values for Human Model 2. 
Other modelling details regarding multiple scattering points, mono-static background channel modelling, and details of the channel generation are also provided. The text proposal for wall reflection model is given in the annex. 
The observations and proposals are summarized as follows:
Proposal 1: Adopt Table 1 and Table 2 as the starting point to finalize the parameter values of the mono-static RCS pattern for AGV modelled with multiple scattering points and with single point, respectively. 
Proposal 2: Adopt Table 3 as the starting point to finalize the RCS pattern for Human model 2. 


Observation 1: When the scattering angle lies in the reflection direction, a strong reflection path can be received by the Rx from the side surface of the vehicle. 
Observation 2: When incident angle is 0 degree, a shadowing zone can be observed from the scattering angle 160 to 180 degrees due to the self-blockage of the vehicle as shown in Figure 4. Meanwhile, a diffraction phenomenon can be observed at 160 degrees, i.e. the scattering power is a little bit higher than from the other scattering angles.
Observation 3: The Option 1-E gives the minimum RMSE result.
Proposal 3: For both mono-static and bi-static RCS for vehicle, the A*B1 pattern is given by:
-
where
,
.

The values of all the parameters in the above equations are given separately for vehicle with multiple points or with single point as agreed already. 
For mono-static RCS,  is absent, and the angles of () are the incident/scattering angles. 
For bi-static RCS, 
 = is applied to the  within 0~180 degrees. The k= 6 based on the measurement validation.
 is the absolute angle between the incident angle and scattering angle within the plane of incident and scattering rays.
The angles of () are the projections of the bisector angle on the vertical plane and the horizontal plane, respectively.
When the  is 180 degrees, the bi-static RCS value is the minimum value from the bi-static RCS pattern, i.e., .

Proposal 4: When the path loss model of UMi, UMa and RMa scenario of TR38.901 is used for the target channel, only the  is applied in the target channel irrespective of the breakpoint distance.

Observation 4：NLOS condition and blockage are essentially different aspects of the model. NLOS condition is defined as there only exist non-line of sight rays between Tx/Rx and target. Blockage is defined as a temporally variable blocker which does not change the LOS/NLOS state of each link.
Proposal 5: The EO type2 as a large and stationary building should not be defined as a blocker according to the blockage model in TR38.901.

Proposal 6: When the EO type-2 is used to model the indirect paths of the channel, the LOS and NLOS condition is determined by the geometry of the EO, Tx, Rx and ST.
If any of EO type-2 deployed is located on the line-of-sight of one link, the link is determined as NLOS condition, and otherwise the LOS/NLOS condition is determined based on the LOS probability equation.
The LOS/NLOS condition is used to generated the LSPs and SSPs for the stochastic component paths of the link.
If the link is determined as NLOS condition, the specular reflection path by any or any other EO type-2 can still be modelled according to the procedure in Annex 1.

Proposal 7: When sensing target is modelled with multiple scattering points, 
The EO ray is generated per scattering point, i.e. Tx-EO-STsp-Rx, Tx-STsp-EO-Rx.
Proposal 8: For concatenation with EO rays, the EO ray is concatenated with other rays as if it is a LOS ray.
Proposal 9: When EO type-2 is modelled, the CPM, AOA, ZOA, AOD, ZOD in the channel coefficient should be replaced by the relevant parameters according to the EO type-2 generation procedure in the Annex 1, when generating the target channel.
Proposal 10: Adopt the text proposal as in Annex 1 for the wall specular reflection modelling. 

Proposal 11: For background channel, if considering to keep the very low power clusters in the channel, revise the -25dB to [-40dB] in step 6 in section 7.5, TR 38.901.
The reference power for removing cluster can follow the TR38.901 without any other updates.

Proposal 12: The generation and parameters for the background channel for mono-static sensing can be modelled as:
Step1：deploy the reference points as:




The 3D coordinates of the reference points are:

Step 2: generate the clusters following the TR 38.901 generation steps under NLOS condition with modification as
number of clusters = 8.
SF = 2.5
the absolute delay for each cluster generated as

Step 3: Combine the channels of each BS-RP link.


Proposal 13: Spatial consistency among multiple scattering points of the same target could be treated as different links.
Proposal 14: 
Towards defining the channel for link level simulation, adding a new path for each ST on top of the current CDL and/or TDL table, where the new path is of parameters for normalized delay, power, angle (AOA, ZOA, AOD, ZOD) and velocity.
The Table 5,Table 6,Table 7,Table 8 and Table 9 under Annex 2 can be referred to for the CDL-A, CDL-B, CDL-C, CDL-D and CDL-E for the ISAC link level simulation, respectively.
The Table 10,Table 11,Table 12,Table 13 and Table 14 under Annex 2 can be referred to for the TDL-A, TDL-B, TDL-C, TDL-D and TDL-E for the ISAC link level simulation, respectively.
The parameter values of the sensing target path is up to the purpose of link level simulation and can be decided together with other simulation assumptions in the evaluation stage.

3GPP TSG RAN WG1 #120bis                                                                                R1-2502286
Wuhan, China, April 7th – 11th, 2025

Source:	OPPO
Title:	Study on ISAC channel modelling
Agenda Item:	9.7.2
Document for:	Discussion and Decision

Conclusions
This contribution is concluded with the following observations and proposals:
Proposal 1: The mono-static RCS (model-2) of a standing human body is dependent on both zenith angle and azimuth angle, and is modeled as 

.,,
with parameters defined as:

Proposal 2: Before RAN1 confirms the RAN1 #120 working assumption on absolute delay, RAN1 seeks for an agreement on a LOS scattering model with non-zero  being applied, in order to retain a modeling feature that has already been agreed.
Proposal 3: Rel-19 ISAC channel model can provide informational examples of specific micro-Doppler functions (e.g. functions in Table 1) for interested sensing targets. 
Proposal 4: Maximum speed and ratio of moving scatters depends on scenarios. 
Speed of 95%-100% moving scatters follows uniform distribution between 0 and 180km/h for UAV case 
Speed of 95%-100% moving scatters is 0 for indoor case 
Speed of 50% moving scatters is 3-60km/h and speed of remaining moving scatters is 0 for UMa/UMi.
Proposal 5: The power normalization in combining the target channel(s) and background channel is formulated as a linear programming problem, solved as following. 
The power normalization coefficient for the background channel is 
The power normalization coefficient for a target channel is 
where 
The value of  has two options
Option 1: , i.e., the power normalization includes both LOS and NLOS in background channel. The K-factor for the whole Tx-Rx channel may change after target channels join in. 
Option 2: , i.e., the power normalization includes NLOS in background channel but not LOS in background channel. The K-factor for the whole Tx-Rx channel remains unchanged after target channels join in.
 for  are power of K target channels between Tx and Rx for K targets.
  is the lower bound of power normalization coefficient for the background channel, to protect the background channel power from reducing to an unreasonable low value. 
Proposal 6: The mono-static background channel model for indoor scenario can be modeled with either of the following two options based on a general parameterized Gamma distribution  with PDF function :
Option 1:
The background channel is generated with N=3 reference points (virtual Rx’s). Each reference point is characterized by a 3D distance (d3D) and a LOS_ZOD direction from the mono-static Tx/Rx.
The 3D distance (d3D) follows: .
The LOS_ZOD follows:.
Option 2:
The background channel is generated with N=3 reference points (virtual Rx’s). Each reference point is characterized by a 2D distance (d2D) from the mono-static Tx/Rx and a height.
The 2D distance (d2D) follows:.
The height (h) follows: .

3GPP TSG RAN WG1 Meeting #120bis		R1-2502326
Wuhan, China, April 7th – 11st 2025

Agenda item:	9.7.2
Source:	Sony
Title:	Discussion on Channel Modelling for ISAC  
Document for:	Discussion and Decision

Conclusion
In this contribution, we share our views on the development of ISAC channel model. We made the following observations:
Observation 1: A certain level of consistency/correlation of RCS can be observed from simulation result. The measured correlation angles are 6.87 º for option 2 small-size UAV.


Proposal 1: Determine the LOS/NLOS state of the path by the geometry of TX, RX, ST and EO by the following condition: If the type-2 EO blocks the LOS then the link is determined as NLOS condition. Otherwise, the LOS probability methodology defined in TR 38.901 is used to determine the LOS/NLOS condition.
Proposal 2: EO type-2 modelling needs to be defined in different sensing scenario (e.g., one or more EO-type-2) and further study the method to combine channel components from different EO type-2s in the target channel.
Proposal 3: The environment object (EO) that are common to both target channel and background channel, such as EO1, should be considered in the background channel modelling.
Proposal 4: Support Option 1 on the combined ISAC channel: the ISAC channel of a pair of sensing Tx/Rx is obtained by summing the target channel(s) and background channel, i.e., power normalization is not performed.
Proposal 5: Support only one A value for the same target type.
Proposal 6: Support the same A value for both monostatic and bistatic case for the same target type, as the RCS directivity effect is already covered by B1.
Proposal 7: For the same scattering point, the correlation of B2 values of rays with different incident/scattered angles can be described by , where  is the measured correlation angle.
Proposal 8: The XPR value for small size UAV option 2 measured at 3.5 GHz is 10.80 dB.

3GPP TSG RAN WG1 Meeting #120bis	R1-2502379
Wuhan, China, April 7th – 11st, 2025
Agenda Item:	9.7.2
Title:		Discussion on ISAC channel modelling
Source:	Samsung
Document for:	Discussion and Decision

Conclusion
This contribution discusses the ISAC channel modelling including the framework, target and background environment modelling, spatial consistency and validation of channel modelling. The observations and proposals are summarized as follows: 
Proposal 1: Support separate LOS cluster modelling method for Tx-target link and target-Rx link for bi-static sensing mode considering two links may have different propagation conditions
Proposal 2: Support a shared LOS cluster modelling method for mono-static sensing modes, as Tx-target link and Target-Rx link are likely to have significant similarities
Observation 1: Sensing signal may become too weak to be detectable or provide any useful information about the target after a certain number of bounces.
Proposal 3: If adopting power threshold-based path dropping method to reduce complexity, a further power normalization after link concatenation should be considered. 
Proposal 4: For path dropping method, the power of concatenated paths should include the effect of target RCS, e.g., the angle-dependent A and/or B1. 
Observation 2: Due to the limited beams for sensing, the sensing beam direction might not be the LOS path 
Proposal 5: The existing distance-based probability model in TR 38.901 can be used as a starting point to determine the LOS/NLOS state between the target and Tx/Rx
Proposal 6: RAN1 to consider the following three options for the impact of the type-2 EO on the LOS/NLOS conditions
- Option #1:  Reuse the existing LOS probability scheme in TR 38.901 if type-2 EOs are considered as components in the scenario layout
- Option #2: Restrict type-2 EOs to specific areas or locations to avoid impacting the LOS probability
- Option #3: Consider the geometrical locations of EOs in the LOS probability calculation
Observation 3: The mobility of stochastic clutters can be reflected as slow-moving objects following a specific Doppler distribution with an average Doppler of zero, which has a significant impact on target channel modelling 
Proposal 7: RAN1 to clarify the scope of discussion regarding the mobility of stochastic clutters
Proposal 8: Consider reference point for the background channel generation for monostatic sensing mode, and the number of the reference point can be one for simplicity. 
Proposal 9: No need to perform power normalization between target channel and background channel.
Proposal 10: Consider distance-based criteria to determine the number of scattering points of target to be single point scattering point or multiple scattering points. 
Proposal 11: Consider the geometric centre as a reference point as long as it is consistent in both single-point and multi-point model.
Proposal 12: RAN 1 needs to discuss whether LoS condition affects the component A of a RCS for a target type
Proposal 13: Deprioritize the modelling of RCS correlation of a scattering point with adjacent incident/scattered angles. 
Proposal 14: consider modelling spatial consistency of LoS conditions/LSP/SSP for multiple scattering points. 
Proposal 15: Consider an effective RCS based on the respective location/angle and RCS of each scattering point to model the spatial consistency between multiple scattering points of the same target.
Proposal 16: RAN 1 to consider the frequency-dependency of the RCS, large/small scale parameters etc. in the channel modelling
Proposal 17: RAN 1 consider the antenna pattern-like approach for RCS modeling of large size UAV 
Proposal 18: RAN 1 discuss the RCS values for large size UAV with table 1
Table 1. monostatic RCS of large size UAV with single scattering point

Observation 4: Considering the various sensing modes and deployment scenarios, the validation of all the possible combinations may require a heavy workload
Proposal 19: RAN1 to study how to validate ISAC channel, e.g., real-world measurement, ray tracing, hybrid method

3GPP TSG RAN WG1 #120bis		 	      R1-2502417
Wuhan, China, April 07th – 11st, 2025

Source:           CALTTA, ZTE Corporation, Sanechips
Title:             Discussion on channel modelling for ISAC
Agenda item:      9.7.2
Document for:     Discussion

Conclusion
In this contribution, we provide our measurements, RT simulations, observations, and analysis on ISAC channel modelling, and we have the following observations and proposals:
Proposal 1: Denote
CPMtx,sp,rx = CPMsp,rx . CPMsp . CPMtx,sp
                              = .
The CPM should be normalized considering path dropping, and the normalized CPMtx,sp,rx  can be represented as

Proposal 2: For UAV of small size (Length x Width x Height: 0.3m x 0.4m x 0.2m) at 4.9GHz for both mono-static and bi-static modes:
XPR for the UAV is modelled as log-Normal distribution. Draw linear-scaled XPR value as
	,
Where,  is Gaussian distributed with 24.4and = 3.05. 
Proposal 3: For UAV of small size (Length x Width x Height: 0.3m x 0.4m x 0.2m) at 4.9GHz for bi-static modes, the following values of component A, B1 and B2 are considered as following:
-  Component A: same as component A of mono-static for UAV of small size
-  Component B1:  where  is the 3D bi-static angle between incident and scatter angle, and 

-  Component B2: same as component B2 of mono-static for UAV of small size

Proposal 4: For pedestrian with single scattering point for both mono-static and bi-static modes:
XPR for pedestrian is modelled using log-Normal distributed. Draw XPR values as
,
Where,  is Gaussian distributed with 25.8 and = 2.99. 
Proposal 5: For pedestrian with single scattering point for bi-static modes, the following values of component A, B1 and B2 are considered as following:
-  Component A: same as component A of mono-static for pedestrian.
-  Component B1:  where  is the 3D bi-static angle between incident and scatter angle, and 


-  Component B2: same as component B2 of mono-static for pedestrian.

Proposal 6: For mono-static, the RCS=A*B=A*B1*B2 of a scattering point for a passenger vehicle Type 1/2 can be generated by

-	A has mean RCS value 11.72 m2 corresponding 10.69 dBsm
-	XPR for the Vehicle is modelled using log-Normal distributed. Draw XPR values as
	,
Where,  is Gaussian distributed with 22.3 and = 4.71. 

Proposal 7: For Bi-static, the RCS=A*B1*B2 of a scattering point for a passenger vehicle Type 1/2 can be generated by
The values/pattern A * B1 is deterministic based on incident/scattered angles
Where,

and,
,
,
= *cos((-)/2)*cos((-)/2),


Note： if  then  = *cos().
B2 is generated by log-normal distribution, and the standard deviation of component B2 is 3.41 dB
Proposal 8: The working consumption of absolute delay model referring to values from 7-24GHz study item is confirmed.
Proposal 9: For TRP mono-static sensing, the spatial consistence of background channel is not considered. 
Proposal 10: For UT mono-static sensing, the following extra parameters for background channel should be all-correlated considering the spatial consistency.

Proposal 11: Dual mobility model in TR 38.901 is used to model the Doppler frequency in background channel of UT mono-static, with the velocity of the reference point setting same as velocity of Tx.
Proposal 12: Option 1 is preferred: power normalization between target channel and background channel is not performed.
Proposal 13: Endorse the above step 1-7 for EO type 2 into TR for ISAC channel modeling, where the channel coefficient for the EO reflected path is given by

Proposal 14: The pathloss of NLOS ray due to EO type 2 in the STX-SPST link or SPST-SRX link is calculated 	by									
-	 is the total propagation distance due to EO type2.
Proposal 15: The following contents type-2 EO are considered into TR for ISAC channel modeling
A type-2 EO can be ground, wall, ceiling, etc. The specular reflection at the type-2 EO is considered in the link between STX and SPST or between SPST and SRX. A ray specularly reflected by an type-2 EO is modelled if a specular reflection point can be found within the surface of the type-2 EO. 
When Type-2 EO is present in STX-ST link and/or ST-SRX link, the following modification to the ISAC channel generation in section 7.9.4, 7.9.4.1 and 7.9.4.2 can be used. 
In Step 1 in section 7.9.4, 
b)	Give number of type-2 EO
c)	Give 3D locations of type-2 EO in the global coordinate system
For each type-2 EO, the location of type2 EO could be decided by four edges points, (x1,y1,z1), (x2,y2,z2), (x3,y3,z3), (x4,y4,z4), then the EO-type2 could be visualized as the Figure 7.9.6.1-1.

The plane equation is , in which the value of A, B, and C is given by

In Step 2 in section 7.9.4.1,
[Rapporteur’s note: Further agreement necessary regarding LOS condition when Type-2 EO is present.]

In Step 3 in section 7.9.4.1,
In each STX-SPST link, if a specular reflection point can be found within the surface of the type-2 EO, the pathloss of a NLOS ray of a type-2 EO is (no matter whether it is LOS condition in the STX-SPST link)

The value of  is referred to step9 of section 7.9.6.1.
In each SPST-SRX link, if a specular reflection point can be found within the surface of the type-2 EO, the pathloss of a NLOS ray of a type-2 EO is (no matter whether it is LOS condition in the SPST-SRX link)

The value of  is referred to step9 of section 7.9.6.1.

Between Step 8 and 9 in section 7.9.4.1, insert following steps to generate NLOS rays of type-2 EO.
In each STX-SPST link, a NLOS ray specularly reflected by a type-2 EO is modelled if a specular reflection point can be found within the surface of the type-2 EO. The followings steps are used to generate NLOS rays of type-2 EO:
Calculate the reflection point.
Denote the absolute location of STX and SPST as  and . The reflected image of STX on the other side of EO type2 is denoted as  , in which 

Based on reflected image of STX and the plane equation of EO type-2, the location of reflection point is , and

If the reflection point  can be found within the surface of the type-2 EO, the NLOS ray specularly reflected by a type-2 EO is modelled.
Calculate arrival angles and departure angles for both azimuth and elevation of NLOS ray of EO type-2
The departure angles in GCS for azimuth and elevation is calculated based on the location of STX and reflection points on EO type-2:


The arrival angles in GCS for azimuth and elevation is calculated based on the location of SRX and reflection points on EO type-2:



In each SPST-SRX link, a NLOS ray specularly reflected by a type-2 EO is modelled if a specular reflection point can be found within the surface of the type-2 EO. The above steps for STX-SPST link could be reused to derive , , and  with the location of STX and SPST as  and  replaced by the location of SPST and SRX as  and .
In Step 9 in section 7.9.4.1, 
In the STX-SPST link, a NLOS ray of EO type-2, if present, is represented by . In the SPST-SRX link, a NLOS ray of EO type-2, if present, is represented by .
In Step 10 in section 7.9.4.1, 
After Step 11 in section 7.9.4.1, the outcome of Steps 1-11 shall be identical for all the links from co-sited sectors to a STX/ST/EO/SRX. 

In Step 13 in section 7.9.4.1, 
In the generation of channel coefficient  for a path  interacting with type-2 EO in set R 
If EO type-2 is present in the SPST-SRX link,  is defined as
in which  and  is generated by

The , ,  and  are the unit direction vector of , ,  and , which are

The  is the normal vector of plane of incidence, which is  and 

The reflection coefficients  and  are derived as following,

in which is the incidence angle given by

The value of complex relative permittivity of the EO type2 material  would reuse the value of defined in TR38.901.

If EO type-2 is present in the STX-SPST link,  is defined as
in which  and  is generated by

The , ,  and  are the unit direction vector of , ,  and , which are

The  is the normal vector of plane of incidence, which is  and 

The reflection coefficients  and  are derived as following,

in which is the incidence angle given by

The value of complex relative permittivity of the EO type2 material  would reuse the value of defined in TR38.901.
In the channel impulse response of SPST p of ST k, , for NLOS ray generated by EO type-2, if present in STX-SPST link,
 

For NLOS ray generated by EO type-2, if present in SPST-SRX link,

Proposal 16: Using the CDL channel as the starting point for research on ISAC LLS, and the method 2 to add new sensing clusters based on the number of sensing targets is preferred. 
Proposal 17: The procedure of hybrid channel modelling with RT simulation in TR 38.901 can be reused and enhanced for sensing. Specify the following typical maps and characteristics of sensing targets to align the simulation assumptions:
Urban grid map defined in 3GPP TR 37.885 
The well-known Manhattan map from open source
Indoor map defined in IEEE 802.11 WLAN
EM parameters defined for radar material by ITU 

3GPP TSG RAN WG1 #120bis	                                                                                         R1-2502419
Wuhan, China   Apr 07th – Apr 11th, 2025
Source:	                    BUPT, CMCC, VIVO, X-Net
Title:	                         ISAC Channel Modeling and Measurement Validation 
Agenda Item:	          9.7.2
Document for:	     Discussion and Decision

Conclusion 
In this contribution, we conduct field measurement validations and simulation analyses of ISAC channel, leading to a number of observational conclusions and modeling insights. The observations and proposals are as follows:
Observation 1: 	From the experiment measurements, there are three peaks in the incident (back scattering), specular scattering and other scattering (e.g., forward scattering) angles, observed over the angular ranges of ϕ= [0⁰,360⁰] and θ= [0⁰,180⁰].
Observation 2: 	From the experiment measurements, there are four peaks in the incident (back scattering), two parts of the specular scattering and other scattering (e.g., forward scattering) angles, observed over the angular ranges of ϕ= [0⁰,360⁰] and θ= [0⁰,180⁰].
Observation 3：The channel generated using 3 reference points better matches the angular spread of the measured mono-static background channel over a 360° horizontal range compared to that generated using a single reference point.
Observation 4: In UMa scenarios, when three reference points (N=3) are spaced at 120° horizontal intervals, the path loss, cluster delay, and cluster AOD/EOD distributions generated according to 3GPP TR 38.901 show strong agreement with the RT simulation results.
     
     
Observation 5：When the target is located at different positions within the same environment, the original clusters/paths in the background channel exhibit blocking effects around the target’s angle. 
Observation 6: The fitness between the formula of micro-Doppler frequency  and the experiment results is well.
Table. 1 Parameters for component  of the monostatic RCS of large UAV
Proposal 1: For large UAV monostatic RCS, the detail parameters of  are shown in Table. 1, the  follows a normal distribution with a mean of -0.79dB and a standard deviation of 2.62dB, respectively, and A is -2.06dB optionally.
Table. 2 Modified parameters for component  of the monostatic RCS of AGV
Proposal 2: For AGV monostatic RCS, the detail parameters of  are shown in Table. 2, and  follows a normal distribution with a mean of -0.4dB and a standard deviation of 1.89dB.
Proposal 3: No experimental or simulation results have been found to demonstrate the angle dependence of human RCS, so it is not recommended to discuss Model 2 for human RCS.
Proposal 4: For human, vehicle, and UAV as sensing targets, the element  of cross polarization matrix of the scattering point  follows a normal distribution. The distributions are as follows:, , .
Proposal 5: RAN1 models the bi-static RCS associated with each incident angle by independently considering multiple bi-static RCS components, for different use case target.
Proposal 6: To calculate  for bi-static RCS in the direction of back-scattering and ensure a consistency between mono-static RCS and bi-static RCS at the incident angle, RAN1 reuses the same formula (Eq. 1) and the same parameters as defined for mono-static RCS.
Proposal 7: To calculate  for bi-static RCS in the direction of specular-scattering, RAN1 considers the same formula (Eq. 1) but with different parameter table as listed Table. 6.
Proposal 8: If the other scattering impact is considered for bi-static RCS, RAN1 independently defines bi-static RCS component in the other-scattering.
Proposal 9: To combine all the bi-static RCS components, select the bi-static RCS component with the maximum RCS value.
Proposal 10: For the bi-static RCS of AGV, the same modelling approach as that for the bi-static RCS of a vehicle can be utilized.
Proposal 11: The bi-static and mono-static RCS model share the same mathematical model at least for small UAV and human.
Proposal 12: The large and small-scale parameters defined in TR 38.901/36.777/37.885 can be reused for background channel in TRP-UE and UE-TRP bi-static sensing. 
Proposal 13：For the method of generating the mono-static background channel using N reference points, N=3 can be considered for a 360° horizontal range.
Proposal 14: In UMa scenarios, the following set of Gamma distribution parameters can be utilized for reference point generation:
     
     
Proposal 15：When combining the target and background channels, different options can be selected based on the scenario category or blockage situation:
Method 1: In UAV scenarios, directly superimpose the target and background channels (Option 1). In indoor/outdoor scenarios, remove background cluster c that are closest to the target in the angular domain and replace them with the target channel (Option 2-Alt 3). 
Method 2：Remove background clusters that are blocked by the target in the angular domain. The possibility of blockage is high in indoor and outdoor scenarios (Option 2-Alt 3) but relatively low in UAV scenarios (Option 1).
Proposal 16: The Micro-Doppler may need to be considered in ISAC channel modelling, and the formula   can be used as a starting point for the modelling of the Micro-Doppler.
Proposal 17: If CPM normalization is considered, it can be accomplished by normalizing each of the three CPMs individually then product, thereby ensuring the overall CPM is normalized.
Proposal 18:  For the UAV-UT case, we recommend modifying the BS height to 1.5 m as per TR 38.858, while ensuring that the angular spread values (ASA and ASD for UT) at the UT side align with those in the corresponding UMi, UMa, and RMa scenarios in TR 38.901.
Proposal 19: For UAV TR selection in FR2, we propose retaining the LOS probability and path loss calculations from TR 36.777, while adopting Alternative 3 for fast fading modeling (K=15, with all other parameters following TR 38.901).
Proposal 20: For targets such as small UAVs, large UAVs (in RMa and UMa scenarios), and humans, where the large-scale parameters between multiple points are highly correlated, it is recommended to reuse the spatial consistency results of a single point.
Proposal 21:  For targets such as vehicle Type 1, vehicle Type 3, and large UAVs (in UMi scenarios), it is recommended to model the spatial consistency for multiple points separately.
Proposal 22: We suggest calculating the fixed spatial decay coefficients between target multiple points beforehand. Once spatial consistency for any single point is calculated, apply these coefficients to efficiently and accurately model ISAC multi-point spatial consistency.

3GPP TSG RAN WG1 #120bis	R1-2502452
Wuhan, China, April 7th – 11th, 2025

Agenda Item:	9.7.2
Source:	Xiaomi, BJTU, BUPT
Title:	Discussion on ISAC channel model
Document for:	Discussion and Decision

Conclusion
In this contribution, we provide the following proposals.
Proposal 1: For directional monostatic RCS pattern, A can be calculated by spherical integration optionally.
Proposal 2: The bistatic RCS can be modelled based on the following two options.
Option 1: Bistatic RCS is generated based on the transition formula between monostatic RCS and bistatic RCS.
Option 2: Bistatic RCS is constructed into single or multiple angular regions according to scattered angles.
Proposal 3: The correlation of RCS in adjacent incident/scattered angles is not modelled.
Proposal 4: For human bistatic RCS, support to use RCS transition formula  to model the human bistatic RCS.
Proposal 5: For large UAV monostatic RCS, support to model the RCS as A*B1*B2, where A*B1 is modelled as a radiation power pattern whose parameters are shown in Table 3, the mean and standard deviation of B2 are -0.79dB and 2.62dB, respectively, and A is -2.06dB optionally.
Table 3 Parameters of A*B1 for large UAV monostatic RCS.
Proposal 6: For vehicle bistatic RCS, the following two models can be considered
Model 1: Adopt RCS transition formula  to model the human bistatic RCS.
Model 2: For each incident angle, one or two peaks corresponding to specular reflection are modelled based on the monostatic radiation pattern parameter, where A*B1 is defined in Table 6, and the standard deviation of B2 is 7.19dB.
Table 6 Parameters of A*B1 for vehicle bistatic RCS.
Proposal 7: For polarization matrix of scattering point, the XPR ratio is generated as  where  is Gaussian distributed with standard deviation  and mean 
for human,  and ;
for large UAV,  and ;
for vehicle,  and .
Proposal 8: For polarization matrix of scattering point, do not support to model the spatial consistency of random phase when a scattering point moves.
Proposal 9: For mono-static sensing, the following table can be used for generating target channel.
Proposal 10: The impacts of target height/scattering point height on LOS probability for Tx to target link and target to Rx link have been captured in existing TRs.
Proposal 11: When the EO type-2 is modelled in the target channel, Option A is preferred to determine the LOS condition of the Tx-target link and target-Rx link.
Option A: If type-2 EO is in the LOS ray of one link, the link is determined as NLOS condition, and otherwise use the LOS probability equation to determine the LOS/NLOS condition
-	Reuse the LOS probability defined in existing TRs
-	Blockage by EO type-2 is not modeled
Proposal 12: The minimum height of UT should be extended to [X]m to include the target height/scattering point height in the pathloss model in scenario UMi, UMa, and RMa, where [X]m is the minimum height of a target/scattering point.
Proposal 13: Power normalization on the product of 3 component CPM matrixes is not needed.
Proposal 14: When path dropping after concatenation is considered for concatenation option 0 and option 3, the power threshold -40dB and -45dB can be used, and -45dB is preferable.
Proposal 15: Further power normalization of target channel after path dropping is not considered.
Proposal 16: The set of remaining indirect paths can be updated during movement of Tx, target, or Rx after a certain period, and it can be up to implementation in the SLS platform.
Proposal 17: The following table can be used for determination of maximum speed of moving scatterers and ratio of moving scatterers among all scatterers.
Proposal 18: For the background channel of the ISAC channel model, modeling EO type-2 in the background channel can be an optional feature.
Proposal 19: The power threshold -25dB for removing clusters in step 6 can be reused for bistatic sensing mode.
No need to add additional very low power clusters
The reference power for removing cluster is the max. Tx-Rx cluster power
Proposal 20: The following reference TRs are preferred for ISAC channel model (highlighted parts are from previous agreements).
Proposal 21: Adopt to generate the Tx-target link and the target-Rx link in the target channel, the following mapping between STX/SRX, target and the proper case of existing TRs is adopted.
Proposal 22: To generate the background channel of bistatic sensing mode, the following mapping between STX/SRX and existing TRs is adopted.
Proposal 23: The spatial correlations among random variables generating channels of links with different types of nodes are not modelled, i.e., BS-BS, BS-UT/ST, and UT/ST-UT
Note: ST and UT are considered as the same type of node.
Proposal 24: The spatial consistency between multiple scattering points of the same target is treated in the same way as spatial consistency between different targets with single scattering points.
Proposal 25: To enable spatial consistency procedure for 3D locations, the spatial consistency procedure is considered as a 3D random process, and the correlation distance is the 3D distance.

3GPP TSG RAN WG1 #120bis	R1-2502466
Wuhan, China, April 7th – 11th, 2025

Agenda Item:	9.7.2
Source:	Toyota ITC
Title:	Discussion on ISAC channel modelling
Document for:	Discussion and Decision

Conclusion
In this contribution we discussed our views on channel modelling for ISAC. Our proposals are summarized as follows: 
Proposal 1: How to select single or multiple scattering points for the target is depending on at least the size of the target.
Proposal 2: RAN1 to model a vehicle as multiple scattering points.

3GPP TSG RAN WG1 #120bis			 R1-2502553
Wuhan, China, April 7th – 11th, 2025
Agenda item:	9.7.2
Source:	Moderator (Xiaomi)
Title:	Summary #1 on ISAC channel modelling
Document for:	Discussion/Decision

Summary #4 on ISAC channel modelling	Moderator (Xiaomi)

3GPP TSG RAN WG1 #120bis			 R1-2502554
Wuhan, China, April 7th – 11th, 2025
Agenda item:	9.7.2
Source:	Moderator (Xiaomi)
Title:	Summary #2 on ISAC channel modelling
Document for:	Discussion/Decision

Proposal
The bistatic RCS of UAV with small size is modelled as
Component A: same as component A of mono-static RCS for UAV of small size
Component B1:  where  is the 3D bi-static angle between incident and scatter angle
Component B2: same as component B2 of mono-static RCS for UAV of small size


Proposed conclusion
No peak of bistatic RCS values is observed in the specular reflection direction for human.

[FL1] Proposal 7.6-1 
The existing 2D correlation distance in Table 7.6.3.1-2 in TR38.901 is reused as 3D correlation distance for ISAC channel at least for UAV scenario

[FL1] Proposal 7.1-2 
When spatial consistency is enabled, the set of paths generated by concatenation Option 3 (1-by-1 random mapping) is not updated during movement of Tx, target and/or Rx. 
Note: the values of delay, angle and power could be changed based on spatial consistency.


[FL1] Proposal 7.1-2 
When spatial consistency is enabled, the 1-by-1 random coupling generated by concatenation Option 3 is not updated during movement of Tx, target and/or Rx.


Wednesday (Apr. 9)

[FL2] Proposal 7.1-2-rev1 
When spatial consistency is enabled, the 1-by-1 random coupling generated by concatenation Option 3 is not updated .


[FL2] Proposal 7.6-1-rev1 
The existing horizontal correlation distance in Table 7.6.3.1-2 in TR38.901 is reused as vertical correlation distance for ISAC channel at least for UAV scenario


[FL2] Proposal 4.1.1-2-rev2
For vehicle with single/multiple SPSTs, down select one option from the following options generating bistatic RCS. 
Option A:
The values/pattern of A*B1 of bistatic RCS is given by:

	where


 is applied to the  within 0~180 degrees. The k= 6 based on the measurement validation.  is the absolute angle between the incident angle and scattering angle within the plane of incident direction () and scattering direction ().
The angles of () are the projections of the bisector angle on the vertical plane and the horizontal plane, respectively.
The effect of forward scattering  is -Inf in Rel-19
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs
Supported by: Huawei, CATT, ZTE, Xiaomi, OPPO, LGE, Samsung, Nokia, 

Option B:
Define the following two functions


The values/pattern A*B1, denoted as  of the bistatic RCS for a SPST is determined by
A first peak of bi-static RCS centred in the back-scattering direction of the incident direction is calculated as

A second peak of bi-static RCS centred in the specular reflection direction of the incident angle is calculated as

, (it is a concave function) 
For the front of vehicle, k1 = 15, k2 = 1.65
For the back of vehicle, k1 = 17.5, k2 = 1.65
For the left or right of vehicle, k1 = 14.5, k2 = 1.55
For the roof of vehicle, FFS
 is within 0~180 degrees.  is the absolute angle between the incident angle and scattering angle within the plane of incident direction () and scattering direction ().
 is the specular reflection direction, 
The final bistatic RCS value for incident/scattered angles () is 
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs
Supported by: vivo, BUPT, ZTE, CMCC, DOCOMO 

Option C:
Define the following two functions


The values/pattern A*B1, denoted as  of the bistatic RCS for a SPST is determined by
A first peak of bi-static RCS centred in the back-scattering direction of the incident direction is calculated as

A second peak of bi-static RCS centred in the specular reflection direction of the incident angle is calculated as

, (it is a concave function) 
For the front of vehicle, k1 = 15, k2 = 1.65
For the back of vehicle, k1 = 17.5, k2 = 1.65
For the left or right of vehicle, k1 = 14.5, k2 = 1.55
For the roof of vehicle, FFS
 is within 0~180 degrees.  is the absolute angle between the incident angle and scattering angle within the plane of incident direction () and scattering direction ().
 is the specular reflection direction, 
The final bistatic RCS value for incident/scattered angles () is 
The effect of forward scattering  is -Inf in Rel-19
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs
Supported by: vivo, LGE, QC, BUPT, CMCC, DOCOMO, ZTE



[FL2] Proposal 5.10-1 
The following working assumption is confirmed


[FL2] Proposal 5.10-2-rev1 
To generate the absolute delay model for sensing scenarios Urban grid, highway and HST
For Urban grid, the values of parameters for  of scenarios UMa are reused. 
For Highway, the values of parameters for  of scenarios RMa and UMa are reused for FR1 and FR2 respectively. 
For HST, the values of parameters for  of scenarios RMa and UMa are reused for FR1 and FR2 respectively. 


[FL2] Proposal 7.2-1
Spatial consistency is not modelled for
the links that are generated referring to channel models with parameter values of different communication scenarios
E.g., between TRP-target/UT link in one scenario and target/UT-UT link in another scenario
the background channels for TRP monostatic sensing of different TRPs


[FL2] Proposal 7.2-2
Spatial consistency is not modelled between TRP-target/UT link and target/UT-UT link for sensing scenario UMi, InH and InF


[FL2] Proposal 7.1-3 
When spatial consistency is enabled, the set of remaining paths after path dropping after concatenation of Tx-target and target-Rx link is not updated during movement of Tx, target and/or Rx. 

Thursday (Apr. 10)

Proposed offline proposals
Monday (Apr. 7)
After Monday offline session

[FL1] Proposal 5.1-1-rev1 
In order to generate Tx-target link, target-Rx link and the background channel, The above table on reference TRs (excluding the already agreed part) is adopted for the mapping between reference TRs and a pair of nodes (STX, SRX, target) 
FFS RSU type UE


[FL1] Proposal 5.2-1-rev1
Confirm the previous working assumption on background channel for mono-static sensing with the following details:
 reference points are dropped for one Tx, based on the Gamma distribution for distance and height of reference point.
The LOS AOD between Tx and the first reference point is generated based on uniform distribution , and the gap of LOS AOD between the Tx and different reference points keeps as .
The background channel is generated based on the channel generated as in existing TR between the real Tx and the reference point assuming NLOS condition.
The antenna field pattern and array orientation of reference point are set same as Tx. 
Arrival angles for both azimuth and elevation  and  are set equal to departure angles
The absolute delay model [d3D and]  as agreed for bistatic sensing for the same sensing scenario applies. 
The mono-static background channel for the Tx would be sum of channels of the links between the Tx and all related reference points, which is

FFS: Doppler frequency in background channel for monostatic sensing
FFS: whether to add additional very low power clusters
FFS: any update to parameters e.g. angular distribution and delay spread


[FL1] Proposal 5.2-2-rev2
The values of the parameters to generated background channel for TRP monostatic and UE monostatic sensing for each sensing scenario are provided in the following table 
FFS parameter values for other scenarios


[FL1] Proposal 5.2-3-rev1
The small scale parameters used to generate the Tx-target link are respectively same as that of the target-Rx link for monostatic sensing. 

[FL1] Proposal 5.3-1-rev1 
Normalization on the product of three polarization matrixes of a direct/indirect path, i.e., CPMtx,sp,rx= CPMsp,rx . CPMsp . CPMtx,sp is supported
The scaling factor is 

[FL1] Proposal 5.4-2 
Power normalization of target channel after path dropping of the target channel is not supported

[FL1] Proposal 4.2.2-1-rev1 
On the monostatic RCS for human with RCS model 2
The monostatic RCS for a scattering point of the target is generated by
The values/pattern A*B1, i.e.,  is deterministic based on incident/scattered angles

Where,


FFS how many rows of the values/pattern A*B1 are defined for the target
Note: each row has a defined applicable range of  and 
Note: whether the RCS is elevation angle dependent or dependent on both elevation and horizontal angles can be separately discussed


[FL1] Proposal 4.5-1 
The following mean and standard deviation values of XPR of targets are agreed
UAV: (13.75, 7.07) dB
Human: (19.81, 4.25) dB
Vehicle: (21.12, 6.88) dB


[FL1] Proposal 4.1.1-2-rev1
For vehicle with single/multiple SPSTs, down select one option from the following options generating bistatic RCS. 
Option A:
The values/pattern of A*B1 of bistatic RCS is given by:

	where


 is applied to the  within 0~180 degrees. The k= 6 based on the measurement validation.  is the absolute angle between the incident angle and scattering angle within the plane of incident direction () and scattering direction ().
The angles of () are the projections of the bisector angle on the vertical plane and the horizontal plane, respectively.
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs
Supported by: Huawei, CATT, ZTE, Xiaomi, OPPO

Option B:
Define the following two functions


The values/pattern A*B1, denoted as  of the bistatic RCS for a SPST is determined by
A first peak of bi-static RCS centred in the back-scattering direction of the incident direction is calculated as

A second peak of bi-static RCS centred in the specular reflection direction of the incident angle is calculated as

, (it is a concave function) 
For the front of vehicle, k1 = 15, k2 = 1.65
For the back of vehicle, k1 = 17.5, k2 = 1.65
For the left or right of vehicle, k1 = 14.5, k2 = 1.55
For the roof of vehicle, FFS
 is within 0~180 degrees.  is the absolute angle between the incident angle and scattering angle within the plane of incident direction () and scattering direction ().
 is the specular reflection direction, 
The final bistatic RCS value for incident/scattered angles () is 
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs
Supported by: vivo, BUPT, ZTE, CMCC, DOCOMO 

Option C:
Define the following two functions


The values/pattern A*B1, denoted as  of the bistatic RCS for a SPST is determined by
A first peak of bi-static RCS centred in the back-scattering direction of the incident direction is calculated as

A second peak of bi-static RCS centred in the specular reflection direction of the incident angle is calculated as

, (it is a concave function) 
For the front of vehicle, k1 = 15, k2 = 1.65
For the back of vehicle, k1 = 17.5, k2 = 1.65
For the left or right of vehicle, k1 = 14.5, k2 = 1.55
For the roof of vehicle, FFS
 is within 0~180 degrees.  is the absolute angle between the incident angle and scattering angle within the plane of incident direction () and scattering direction ().
 is the specular reflection direction, 
The final bistatic RCS value for incident/scattered angles () is 
 is -Inf in Rel-19
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs
Supported by: vivo, LGE, QC, BUPT, 


[FL1] Proposal 4.1.1-1
No special handling of RCS values in the forward scattering directions in Rel-19 SI
The existing blockage model B is reused to model the blocking effect due to a target as an optional feature 
Applicable to the LOS/NLOS rays in the background channel of the target

Tuesday (Apr. 8)
After Tuesday offline session

[FL1] Proposal 4.1.1-2-rev2
For vehicle with single/multiple SPSTs, down select one option from the following options generating bistatic RCS. 
Option A:
The values/pattern of A*B1 of bistatic RCS is given by:

	where


 is applied to the  within 0~180 degrees. The k= 6 based on the measurement validation.  is the absolute angle between the incident angle and scattering angle within the plane of incident direction () and scattering direction ().

The angles of () are the projections of the bisector angle on the vertical plane and the horizontal plane, respectively.
 is -Inf in Rel-19
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs
Supported by: Huawei, CATT, ZTE, Xiaomi, OPPO, LGE, Samsung, Nokia, 

Option B:
Define the following two functions


The values/pattern A*B1, denoted as  of the bistatic RCS for a SPST is determined by
A first peak of bi-static RCS centred in the back-scattering direction of the incident direction is calculated as

A second peak of bi-static RCS centred in the specular reflection direction of the incident angle is calculated as

, (it is a concave function) 
For the front of vehicle, k1 = 15, k2 = 1.65
For the back of vehicle, k1 = 17.5, k2 = 1.65
For the left or right of vehicle, k1 = 14.5, k2 = 1.55
For the roof of vehicle, FFS
 is within 0~180 degrees.  is the absolute angle between the incident angle and scattering angle within the plane of incident direction () and scattering direction ().
 is the specular reflection direction, 
The final bistatic RCS value for incident/scattered angles () is 
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs
Supported by: vivo, BUPT, ZTE, CMCC, DOCOMO 

Option C:
Define the following two functions


The values/pattern A*B1, denoted as  of the bistatic RCS for a SPST is determined by
A first peak of bi-static RCS centred in the back-scattering direction of the incident direction is calculated as

A second peak of bi-static RCS centred in the specular reflection direction of the incident angle is calculated as

, (it is a concave function) 
For the front of vehicle, k1 = 15, k2 = 1.65
For the back of vehicle, k1 = 17.5, k2 = 1.65
For the left or right of vehicle, k1 = 14.5, k2 = 1.55
For the roof of vehicle, FFS
 is within 0~180 degrees.  is the absolute angle between the incident angle and scattering angle within the plane of incident direction () and scattering direction ().
 is the specular reflection direction, 
The final bistatic RCS value for incident/scattered angles () is 
 is -Inf in Rel-19
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs
Supported by: vivo, LGE, QC, BUPT, CMCC, DOCOMO, ZTE

Wednesday (Apr. 9)

[FL2] Proposal 5.2-1-rev2
On background channel for mono-static sensing, the following details are provided:
 reference points are dropped for one Tx, based on the Gamma distribution for distance and height of reference point.
The LOS AOD between Tx and the first reference point, which is denoted as AOD1, is generated based on uniform distribution .
The LOS AOD between Tx and the second reference point is AOD1 + 
The LOS AOD between Tx and the third reference point is AOD1 + 
The background channel is generated based on the channel generated as in existing TR between the real Tx and the reference point assuming NLOS condition.
The antenna field pattern and array orientation of reference point are set same as Tx. 
Arrival angles for both azimuth and elevation  and  are set equal to departure angles
The absolute delay model [d3D and]  as agreed for bistatic sensing for the same sensing scenario applies. 
The mono-static background channel for the Tx would be sum of channels of the links between the Tx and all related reference points, which is

FFS: Doppler frequency in background channel for monostatic sensing
FFS: whether/howto add additional very low power clusters
FFS: any update to parameters e.g. angular distribution and delay spread


[FL2] Proposal 5.4-3 
To generate the background channel, the power threshold for removing clusters in step 6 in section 7.5, TR 38.901 is -40 dB 

[FL2] Proposal 5.4-4 
The ISAC background channel can be generated between a sensing Tx and a sensing Rx or RP (relevant for monostatic case) via the following steps:
Step 1: generate a first set of clusters/rays according to TR 38.901
Step 2: generate a second set of NLOS clusters/rays according to TR 38.901, where the power of the second set of clusters/rays should be scaled down such that


(,   are the power of the n-th cluster from the first and second set, respectively).
FFS any modification from 38.901 for the second set including the number of clusters N, and the number of rays within each cluster M, value of G, the large scale statistics (for generation of the second set of clusters)
Example 0. G = -25dB
Example 1 N=360, M=1, G=0dB, with uniform delay and angle (for mono-static case)
Example 2 N=120, M=1, G = -25dB, no further change from 38.901
Note: the step 2 is an additional modeling component

[FL2] Proposal 5.2-2-rev2
The values of the parameters to generated background channel for TRP monostatic and UE monostatic sensing for each sensing scenario are provided in the following table 
FFS parameter values for other scenarios


Thursday (Apr. 10)


Physical object model
E//: Angle-dependent RCS model of a target is provided for a given target’s local coordinate system
[H] Bistatic RCS
General on bistatic RCS

Summary on company views

Design issues on bistatic RCS
Whether/how to model a peak in the specular reflection direction (RCS_s())?
Yes: QC, E//, NIST, vivo, BUPT, ZTE, Xiaomi, Spreadtrum
What is the trend of the peak values with the change of incident direction?
roughly monotone: HW, ZTE
concave function: vivo, BUPT 
Whether/how to model a peak of the back scattering in the incident direction, which is equal to the monostatic RCS in the incident direction (RCS_i())?
Yes: QC, vivo, BUPT
Whether/how to model a shadow or peak in the forward scattering region?
peak: QC, LGE, vivo, BUPT, Apple
shadow: QC, HW, NIST, ZTE, 
To combine all the bi-static RCS components, select the bi-static RCS component with the maximum RCS value, : vivo, BUPT

CATT: min{,  RCS_MIN}
CT, LGE: 
Nokia
For bistatic RCS, use the bistatic angle to define at least two angular regions.
When bistatic angle , the bistatic RCS , at least , where  is monostatic RCS value.
When  is close to 180 degree, further study how to model bistatic RCS with forward scattering links.
LGE: 3 angular regions
LGE: Model the forward scattering RCS as a deterministic function , where angles  are determined w.r.t. the Tx to target line, Daz and Del are the effective extents of sensing target in azimuth and elevation domains, respectively. Define the angular width of the forward scattering region centered at  as  [rad].
E//: The bistatic RCS model should have a small, close-to-zero value in the forward scattering region if shadowing of the object is modelled using a blocker.

Shadows behind targets
Shadows behind targets should be odellin: Ericsson
Shadow is distance dependent: Ericsson

Ericsson: sensing Rx is likely to locate in the near field of a large target, where shadow effect needs to be taken into account

To model a shadow
large RCS in the shadow region than in other directions and with opposite phase to that of background channel so that H_target≈-H_background and H_ISAC=H_background+H_target becomes small
Ericsson
conflict with the agreement on scalar RCS odelling
without phase, it creates an energy increase behind the target, which breaks the laws of physics
The RCS needs to be dependent on both Tx-target distance and target-Rx distance to generate the correct “depth” of the shadow
Blockage model so that  is reduced in the shadow region: E//, NIST
E//: Blocking can simplify RCS modelling tremendously. Without the very strong forward scattering component, RCS is much easier to model
E//, Lenovo: The blockage of one target can be considered in the Tx-target and/or target-Rx links of another target channel depending on sensing mode.

NIST: We should explore how to model forward-scattering beyond shadowing region. Option 1: Continue using the blockage model, which models the combined behaviour of LOS and diffraction paths. Option 2: Use an effective RCS model based on target diffraction paths to reduce modelling complexity.

Diffraction / blockage model
The existing blockage model B is reused to model the blocking effect due to a target as an optional feature
Applicable to the LOS/NLOS rays in the background channel of the target
Applicable to the LOS/NLOS rays in the Tx-target and target-Rx link of the other target
Supported by: Ericsson, Lenovo, IDC, SONY, BUPT, DOCOMO, NIST
OK for optional feature: HW, Nokia, LGE, CATT, Samsung, QC
NO: vivo, ZTE

NVIDIA: blockage and forward scattering between sensing targets should be modelled in the target channel

Reciprocity
E//: The modelled RCS should be reciprocal 

[Moderator’s note] It is quite controversial whether/how to model diffraction/forward scattering. Some validation results show it is a peak in the forward scattering region, while other validation results indicate it is a shadow. The proposal on modeling a peak or a shadow is also diverged. The reason for the different measurements may be due to the assumed target to receiver distance. 
Considering the limited remaining Tus of the study item, it is generally not preferred to model distance dependent RCS for diffraction/forward scattering. 
As discussed by Ericsson and NIST, modelling a large RCS for forward scattering results in high total power received at the receiver, since the LOS ray in the background channel is modelled in the ISAC channel too. Given blockage model B can serve the purpose to model diffraction, we may not pursue a special handling on RCS for forward scattering in the limited remaining time for study. 
[FL1] Proposal 4.1.1-1
No special handling of RCS values in the forward scattering directions in Rel-19 SI
The existing blockage model B is reused to model the blocking effect due to a target as an optional feature 
Applicable to the LOS/NLOS rays in the background channel of the target


[Moderator’s note] Based on the companies’ inputs, the following two options (mainly for vehicle) get some supports. Both options have the following merits
The bistatic RCS for the backscatter of incident direction is equal to the monostatic RCS in the same direction
It generates a peak at the specular reflection direction
Both options will generate one peak at the backscatter of incident direction, up to 3 peaks for specular reflection since an incident ray can luminate up to 3 surfaces of the vehicle, e.g., front/left/roof for a transmitter in left-front direction with 
Note: for easy discussion, I now rename the following two options as Option A and Option B. 

For Option B, please provide your view on Alt 1 and Alt 2 to generate the peak RCS values of specular reflection direction. Alt 1 is originally proposed by vivo/BUPT, while Alt 2 is added by the moderator to align Option A/B. Not sure if Alt 2 can be a compromise since it uses a spirit of Option A. Other alternatives are not precluded at the moment. 
[FL1] Proposal 4.1.1-2
For vehicle with single/multiple SPSTs, down select one option from the following options generating bistatic RCS. 
Option A:
The values/pattern of A*B1 of bistatic RCS is given by:

	where
,
.
 is applied to the  within 0~180 degrees. The k= 6 based on the measurement validation.  is the absolute angle between the incident angle and scattering angle within the plane of incident direction () and scattering direction ().
The angles of () are the projections of the bisector angle on the vertical plane and the horizontal plane, respectively.
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs

Option B:
Define the following two functions


The values/pattern A*B1, denoted as  of the bistatic RCS for a SPST is determined by
A first peak of bi-static RCS centred in the back-scattering direction of the incident direction is calculated as

A second peak of bi-static RCS centred in the specular reflection direction of the incident angle is calculated as

Alt 1: , (it is a concave function) 
For the front of vehicle, k1 = 15, k2 = 1.65
For the back of vehicle, k1 = 17.5, k2 = 1.65
For the left or right of vehicle, k1 = 14.5, k2 = 1.55
For the roof of vehicle, FFS
Alt 2:  (decreasing with increased bistatic angles)
The k= 6 based on the measurement validation.
 is within 0~180 degrees.  is the absolute angle between the incident angle and scattering angle within the plane of incident direction () and scattering direction ().
 is the specular reflection direction, 
The final bistatic RCS value for incident/scattered angles () is 
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs



[FL1] Proposal 4.1.1-2-rev1
For vehicle with single/multiple SPSTs, down select one option from the following options generating bistatic RCS. 
Option A:
The values/pattern of A*B1 of bistatic RCS is given by:

	where


 is applied to the  within 0~180 degrees. The k= 6 based on the measurement validation.  is the absolute angle between the incident angle and scattering angle within the plane of incident direction () and scattering direction ().
The angles of () are the projections of the bisector angle on the vertical plane and the horizontal plane, respectively.
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs
Supported by: Huawei, CATT, ZTE, Xiaomi, OPPO

Option B:
Define the following two functions


The values/pattern A*B1, denoted as  of the bistatic RCS for a SPST is determined by
A first peak of bi-static RCS centred in the back-scattering direction of the incident direction is calculated as

A second peak of bi-static RCS centred in the specular reflection direction of the incident angle is calculated as

, (it is a concave function) 
For the front of vehicle, k1 = 15, k2 = 1.65
For the back of vehicle, k1 = 17.5, k2 = 1.65
For the left or right of vehicle, k1 = 14.5, k2 = 1.55
For the roof of vehicle, FFS
 is within 0~180 degrees.  is the absolute angle between the incident angle and scattering angle within the plane of incident direction () and scattering direction ().
 is the specular reflection direction, 
The final bistatic RCS value for incident/scattered angles () is 
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs
Supported by: vivo, BUPT, ZTE, CMCC, DOCOMO 

Option C:
Define the following two functions


The values/pattern A*B1, denoted as  of the bistatic RCS for a SPST is determined by
A first peak of bi-static RCS centred in the back-scattering direction of the incident direction is calculated as

A second peak of bi-static RCS centred in the specular reflection direction of the incident angle is calculated as

, (it is a concave function) 
For the front of vehicle, k1 = 15, k2 = 1.65
For the back of vehicle, k1 = 17.5, k2 = 1.65
For the left or right of vehicle, k1 = 14.5, k2 = 1.55
For the roof of vehicle, FFS
 is within 0~180 degrees.  is the absolute angle between the incident angle and scattering angle within the plane of incident direction () and scattering direction ().
 is the specular reflection direction, 
The final bistatic RCS value for incident/scattered angles () is 
 is -Inf
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs
Supported by: vivo, LGE, QC, BUPT, 


[Moderator’s note] Further revised based on offline discussions

[FL2] Proposal 4.1.1-2-rev2
For vehicle with single/multiple SPSTs, down select one option from the following options generating bistatic RCS. 
Option A:
The values/pattern of A*B1 of bistatic RCS is given by:

	where


 is applied to the  within 0~180 degrees. The k= 6 based on the measurement validation.  is the absolute angle between the incident angle and scattering angle within the plane of incident direction () and scattering direction ().
The angles of () are the projections of the bisector angle on the vertical plane and the horizontal plane, respectively.
The effect of forward scattering  is -Inf in Rel-19
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs
Supported by: Huawei, CATT, ZTE, Xiaomi, OPPO, LGE, Samsung, Nokia, 

Option B:
Define the following two functions


The values/pattern A*B1, denoted as  of the bistatic RCS for a SPST is determined by
A first peak of bi-static RCS centred in the back-scattering direction of the incident direction is calculated as

A second peak of bi-static RCS centred in the specular reflection direction of the incident angle is calculated as

, (it is a concave function) 
For the front of vehicle, k1 = 15, k2 = 1.65
For the back of vehicle, k1 = 17.5, k2 = 1.65
For the left or right of vehicle, k1 = 14.5, k2 = 1.55
For the roof of vehicle, FFS
 is within 0~180 degrees.  is the absolute angle between the incident angle and scattering angle within the plane of incident direction () and scattering direction ().
 is the specular reflection direction, 
The final bistatic RCS value for incident/scattered angles () is 
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs
Supported by: vivo, BUPT, ZTE, CMCC, DOCOMO 

Option C:
Define the following two functions


The values/pattern A*B1, denoted as  of the bistatic RCS for a SPST is determined by
A first peak of bi-static RCS centred in the back-scattering direction of the incident direction is calculated as

A second peak of bi-static RCS centred in the specular reflection direction of the incident angle is calculated as

, (it is a concave function) 
For the front of vehicle, k1 = 15, k2 = 1.65
For the back of vehicle, k1 = 17.5, k2 = 1.65
For the left or right of vehicle, k1 = 14.5, k2 = 1.55
For the roof of vehicle, FFS
 is within 0~180 degrees.  is the absolute angle between the incident angle and scattering angle within the plane of incident direction () and scattering direction ().
 is the specular reflection direction, 
The final bistatic RCS value for incident/scattered angles () is 
The effect of forward scattering  is -Inf in Rel-19
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs
Supported by: vivo, LGE, QC, BUPT, CMCC, DOCOMO, ZTE



[Moderator’s note] Multiple companies propose that there is no specular reflection for human. One company prefer to model specular reflection for human. But please check if the proposal based on majority view is acceptable. 
[FL2] Proposal 4.1.1-3 for conclusion
No peak of bistatic RCS values is observed in the specular reflection direction for human



[Moderator’s note] For blockage model B, the proponents propose it not only for background channel, but also for interaction between targets. This is the second part of the proposal. Please check if it is agreeable. 
[FL1] Proposal 4.1.1-4 
The existing blockage model B is reused to model the blocking effect due to a target as an optional feature
Applicable to the LOS/NLOS rays in the Tx-target and target-Rx link of the other target



Framework/values for UAV
Summary on company views


CMCC


BUPT, vivo
The bi-static and mono-static RCS model share the same mathematical model at least for small UAV and human.

[Moderator’s note] Better to check if more inputs are available. 

[FL1] Question 4.1.2-1 
If any new results are available, please provide your inputs on values/pattern of A*B1 and (mean, standard deviation) of B2 for UAV of small size


[FL2] Proposal 4.1.2-1 
The bistatic RCS of UAV with small size is modelled as
Component A: same as component A of mono-static RCS for UAV of small size
Component B1:  where  is the 3D bi-static angle between incident and scatter angle
Component B2: same as component B2 of mono-static RCS for UAV of small size



[FL1] Question 4.1.2-2 
If any new results are available, please provide your inputs on values/pattern of A*B1 and (mean, standard deviation) of B2 for UAV of large size




Framework/values for human 
Summary on company views



E//: To model the scattering off an upright human, linear , where  is an attenuation factor defined in terms of the bistatic angle  as  and  is a modified version of the antenna radiation pattern from TR38.901 defined in decibel scale as follows .
AT&T: For bistatic sensing, to model the RCS of an adult human target with single scattering point
A is mean RCS value given -14.4 dBsm
B2 is modelled using a log-normal distribution with mean 0 dB and standard deviation of 6.7


[Moderator’s note] Better to check if more inputs are available. 

[FL1] Question 4.1.3-1 
If any new results are available, please provide your inputs on values/pattern of A*B1 and (mean, standard deviation) of B2 for human with RCS model 1


[FL2] Proposal 4.1.2-2 
The bistatic RCS of human with RCS model 1 is modelled as
Component A: same as component A of mono-static RCS for human with RCS model 1
Component B1:  where  is the 3D bi-static angle between incident and scatter angle
Component B2: same as component B2 of mono-static RCS for human with RCS model 1



[FL1] Question 4.1.3-2 
If any new results are available, please provide your inputs on values/pattern of A*B1 and (mean, standard deviation) of B2 for human with RCS model 2



If any additional comments, please provide it in following table


Framework/values for vehicle with single scattering point
Summary on company views


AT&T:  For bistatic sensing, to model the RCS of a large vehicle with single scattering point
B2 is modelled using a log-normal distribution with standard deviation 6.1


[Moderator’s note] Better to check if more inputs are available. 
[FL1] Question 4.1.4-1 
If any new results are available, please provide your inputs on values/pattern of A*B1 and (mean, standard deviation) of B2 for vehicle with single scattering point


[FL1] Question 4.1.4-2 
If any new results are available, please provide your inputs on values/pattern of A*B1 and (mean, standard deviation) of B2 for vehicle with multiple scattering points



If any additional comments, please provide it in following table


Framework/values for AGV
Summary on company views



[Moderator’s note] Better to check if more inputs are available. 
[FL1] Question 4.1.5 
If any new results are available, please provide your inputs on values/pattern of A*B1 and (mean, standard deviation) of B2 for AGV



If any additional comments, please provide it in following table


[H] Monostatic RCS
Nokia: Table 5  3GPP specified parameters for mid-sized UAV for monostatic scenario

Values for UAV of large size
Summary on company views



[Moderator’s note] Better to check if more inputs are available. 
[FL1] Question 4.2.1 
If any new results are available, please provide your inputs on values/pattern of A*B1 and (mean, standard deviation) of B2 for UAV with large size



If any additional comments, please provide it in following table


Framework/values for human with RCS mode 2
Summary on company views

Angular dependency
Horizontal: IDC, OPPO, LGE
Vertical: IDC, HW, DOCOMO
Not support: BUPT


QC
For model 1, for a child, support a component A which is 5 dBsm lower than the adult:
Component A: -6.37 dBsm
Component B1: 0 dB (already agreed in RAN1#118bis)
Component B2: 


[Moderator’s note] Better to check if more inputs are available. 

[FL1] Proposal 4.2.2-1 
On the monostatic RCS for human with RCS model 2
The monostatic RCS for a scattering point of the target is generated by
The values/pattern A*B1, i.e.,  is deterministic based on incident/scattered angles

Where,


FFS how many rows of the values/pattern A*B1 are defined for the target
Note: each row has a defined applicable range of  and 



[FL1] Proposal 4.2.2-1-rev1 
On the monostatic RCS for human with RCS model 2
The monostatic RCS for a scattering point of the target is generated by
The values/pattern A*B1, i.e.,  is deterministic based on incident/scattered angles

Where,


FFS how many rows of the values/pattern A*B1 are defined for the target
Note: each row has a defined applicable range of  and 
Note: whether the RCS is elevation angle dependent or dependent on both elevation and horizontal angles can be separately discussed


[Moderator’s note] Agreement in Tuesday online
Agreement
On the monostatic RCS for human with RCS model 2
The monostatic RCS for a scattering point of the target is generated by
The values/pattern A*B1, i.e.,  is deterministic based on incident/scattered angles

Where,


FFS how many rows of the values/pattern A*B1 are defined for the target
Note: each row has a defined applicable range of  and 
Note: whether the RCS is elevation angle dependent or dependent on both elevation and horizontal angles can be separately discussed


[FL1] Question 4.2.2-2 
If any new results are available, please provide your inputs on values/pattern of A*B1 and (mean, standard deviation) of B2 for Human with RCS model 2



If any additional comments, please provide it in following table



Values for AGV
Summary on company views


Nokia: Table 7  3GPP specified parameters for quadruped robot for monostatic scenario


[Moderator’s note] Better to check if more inputs are available. 
[FL1] Question 4.2.3 
If any new results are available, please provide your inputs on values/pattern of A*B1 and (mean, standard deviation) of B2 for AGV



If any additional comments, please provide it in following table



[H] Value of component A for bistatic and monostatic sensing modes

Summary on company views

E//: For mono-static sensing mode, bi-static RCS modelling is needed for indirect paths
E//: For a type of target, mono-static RCS and bi-static RCS constitute the whole RCS to derive value A, B1 and B2. Such A is used to calculate power scaling factor

Component A
different values of component A respectively for monostatic RCS and bistatic RCS of same target
same value of component A for monostatic RCS and bistatic RCS of same target: Nokia, LGE, vivo, BUPT, ZTE, Ericsson, Sony, Tejas


[Moderator’s note] Based on the compromise agreement in last meeting, we need to decide a value for component A for a target. Multiple companies prefer to define same value A for monostatic/bistatic RCS for simplicity
[FL2] Proposal 4.3-1 
The same value of the component A is applied to the monostatic RCS and the bistatic RCS of a target
Exact value of component A is to be discussed per target


Angular correlation of RCS
Summary on company views

Whether to model correlation of RCS of a scattering point in adjacent incident/scattered angles?
Yes (5): Lenovo, LGE, E//, NIST, Sony
Use a correlation distance: Lenovo
Sum of sinusoids: E//
No (11): ZTE, HW, Nokia, vivo, QC, BUPT, CATT, SS(deprioritized), MTK, Xiaomi, Apple(low priority)

Spatial-temporal consistency of RCS : E//, NIST, Lenovo
E//: Model the stochastic B2 with C random scattering centres as 
NIST:  generated by convolving i.i.d. Lognormal random values with the ACF model,  where .
Sony: 


E//: B2 must be continuous over the incidence and scattering angles
E//: Discontinuous behavior leads to non-physical artifacts in the channel, including very high Doppler frequencies and spurious out-of-band artifacts



LGE: RCS as a random time-domain process:
Sony: Consider correlation angle  [º] on B1

NIST: We observe notable correlations across multiple angle lags , indicating that the small-scale RCS (B2) exhibits some spatial (temporal) correlation

Figure 3-7: Small-Scale RCS (B2) autocorrelation function as a function of angle lag.
Sony
Table 1: Summary of RCS simulation results of UAV model option 2 


[Moderator’s note] The existing validation results show that the RCS values fluctuate a lot with the change of incident/scattered angles. However, the RCS value of close/adjacent incident/scattered angles can still have some correlations as discussed in some contributions. On the other hand, some companies comment that the angle dependent pattern of B1 (or A*B1) is already a means to model correlation of adjacent incident/scattered angles. 
[FL1] Question 4.4-1
Companies are encouraged to comment on whether/how to model correlation of RCS of a scattering point in adjacent incident/scattered angles?


[H] XPR to generate polarization matrix
Summary on company views

Xiaomi, Apple, ZTE, BUPT, QC, Sony: The proposed XPR distribution/value are summarized in following table

CMCC: There’s a clear difference between the CPM distributions of monostatic and bistatic modes.
E//: 
Support any orientation of target by defining  in a Local Coordinate System (LCS) and reusing the procedure for the support of arbitrary orientation of BS and UE in section 7.1 of 38.901
CPMsp must be specified in a local coordinate system, in which the z-axis is parallel to the z-axis in the global coordinate system, .
If the change of orientation leads to a change of z axis, such as a vehicle driving on/off a slope, rotation procedure is needed because the cross-polarization matrix is no longer diagonally dominant.

Nokia: Reuse the TR 38.901 log-normal distribution parameters as baseline: 
 for LOS of Umi, and  for LOS of Uma

[Moderator’s note] Based on the agreement from last meeting, one open issue is to collect the values of mean and standard deviation for XPR. Please provide your values if available. 
[FL1] Question 4.5-1 
If any new results are available, please provide your inputs on the mean and standard deviation of XPR to generate the polarization matrix of a direct/indirect path of a scattering point of UAV, human, vehicle, AGV, and other targets 



[FL1] Proposal 4.5-1 
The following mean and standard deviation values of XPR of targets are agreed
UAV: (13.75, 7.07) dB
Human: (19.81, 4.25) dB
Vehicle: (21.12, 6.88) dB


[Moderator’s note] Agreement in Tuesday online 
Agreement
The following mean and standard deviation values of XPR of targets are agreed for monostatic sensing and bistatic sensing as follows:
UAV: (13.75, 7.07) dB
Human: (19.81, 4.25) dB
Vehicle: (21.12, 6.88) dB

Angular correlation of polarization matrix
Summary on company views

Whether to model correlation of polarization matrix (XPR, initial random phase) of a scattering point in adjacent incident/scattered angles?
Yes: Ericsson, CATT (impact to Doppler), IDC
NO: HW, Nokia, LGE, vivo, BUPT, ZTE, QC, Xiaomi

IDC: Initial random phase and XPR of CPM_sp is link-correlated for spatially consistent mobility odelling of the same target only
CATT
The base station rotation procedure for CPM of target is not necessary because the XPR and random phase are generated statistically.


[Moderator’s note] Unlike the discussion on correction of RCS B2, there is no validation result available for XPR. More inputs from companies are necessary. 
[FL1] Question 4.6-1
Companies are encouraged to comment on whether/how to model correlation of XPR/initial random phase of a scattering point in adjacent incident/scattered angles?


RCS for other targets/EO type-1
Summary on company views

E//: For outdoor human scenario, the type of sensing targets which may be evaluated in future study is not limited to pedestrian and can be cyclists, E-Scooter, and motorcyclists.
E//: For the bistatic RCS of birds, use an isotropic model with A between -40 to -20 dBsm for a single bird, and A = 0 dBsm for a migrant flock.

Ericsson: Use the following bistatic RCS model for a single tree: A*B1 with a constant level of 10 dBm2 and a single lobe in the forward direction with A*B1 increasing to 23 dBm2. The B2 standard deviation is approximately 3 dB.

Nokia: Table 6  3GPP specified parameters for robotic arm for monostatic scenario

LGE: Model the monostatic RCS of animal as the product of the angular independent component A = 1.5 dBsm, the component B1=1 and the component B2 having the standard deviation σ = 3.94 dB.

[Moderator’s note] For any other targets, e.g., object creating hazard on road, or certain EO type-1. If the measurement data are available and agreeable, we would try to complete them in the study item. 
[FL1] Question 4.7-1 
Please provide your inputs on values/pattern of A*B1 and (mean, standard deviation) of B2 for human with RCS model 2



If any additional comments, please provide it in following table


Collection on the setup for RCS measurement from companies 

[Moderator’s note] Based the email discussion [Post-120-ISAC-01] and confirmation by Chair, we would create a document to collect details on the setup for RCS measurement/simulation (i.e. vehicle size, frequency, distance, etc). The file include separate sheets for different target types. Please consider adding your information for measurement/odelling. 
/Inbox/drafts/9.7(FS_Sensing_NR)/9.7.2 Channel Modelling/R1-250xxxx Setup on RCS measurement_v000.xlsx


If any additional comments, please provide it in following table


ISAC channel model
ZTE: Dual mobility model in TR 38.901 is used to model the Doppler frequency in background channel of UT mono-static, with the velocity of the reference point setting same as velocity of Tx.
IDC: An unintended target is a blockage factor in the target channel and further study whether Blockage model A or Blockage model B should be implemented
[H] Reference TRs
Summary on company views

Ericsson
It needs evaluation whether BS-aerial UE in 36.777 can be reused for terrestrial UE-UAV link and terrestrial UE-aerial UE channel, especially for indoor Ues.
It needs evaluation whether BS-aerial UE in 36.777 can be reused for aerial UE-UAV link, because it requires changing BS height from at most 35m to up to 300m (aerial UE height).
Both aerial UE and UAV can be of any same or different heights in the large range of [1.5m, 300m]. It needs consideration whether/how LOS probability, pathloss model, shadow fading parameters for different UAV heights in 36.777 can be extended to support combinations of two heights of aerial UE and UAV.
QC
For TRP/UE to aerial UE for FR2, support reusing the channel model of FR1. 
For aerial-UE to aerial-UE, support reusing the D2D channel model from 36.843 A.2.1.2 is used.
IDC
Reuse UMi-AV, UMa-AV and RMa-AV scenarios of TRP to aerial UE channel model defined in TR 36.777 for channel between a normal UE and an aerial UE as a starting point
Capture the same TRs as case 7 for case 9 to model the channel between two aerial Ues as a starting point.
BUPT
For the UAV-UT case, we recommend modifying the BS height to 1.5 m as per TR 38.858, while ensuring that the angular spread values (ASA and ASD for UT) at the UT side align with those in the corresponding UMi, UMa, and RMa scenarios in TR 38.901.
For UAV TR selection in FR2, we propose retaining the LOS probability and path loss calculations from TR 36.777, while adopting Alternative 3 for fast fading odelling (K=15, with all other parameters following TR 38.901).
CATT
TRP-UAV channel defined in TR 36.777 is used to model the channel between UAV and cellular UE.
Channel model between a UE and a RSU and between two UE-type RSUs reuse the V2V channel model with antenna height at RSU changed to 5m, as defined in TR 37.885.
Channel model between a TRP and a RSU should reuse the B2R link modelling in TR 37.885.

[Moderator’s note] We agreed on the reference TRs for the links between TRP-TRP, TRP-UE and normal UE-normal UE. A basic/rough principle for such agreement is to have 38.901-like option. Such a rule can be extended to other kinds of links. In the following Table x for reference TRs, only one option is kept for each pair of link for each scenario. Please check if it is agreeable. 

Table x: Reference TRs
The related sections in the following existing TRs are used as starting point to generate a channel between any two nodes from TRP, normal UE, vehicle UE and aerial UE. 


[FL1] Proposal 5.1-1 
In order to generate Tx-target link, target-Rx link and the background channel, The above table on reference TRs (excluding the already agreed part) is adopted for the mapping between reference TRs and a pair of nodes (STX, SRX, target) 



[FL1] Proposal 5.1-1-rev1 
In order to generate Tx-target link, target-Rx link and the background channel, The above table on reference TRs (excluding the already agreed part) is adopted for the mapping between reference TRs and a pair of nodes (STX, SRX, target) 
FFS RSU type UE


[Moderator’s note] Agreement from Tuesday online
Agreement
In order to generate Tx-target link, target-Rx link and the background channel, the above table on reference TRs (excluding the already agreed part) is adopted for the mapping between reference TRs and a pair of nodes (STX, SRX, target) 
Note: continue discussion for updating the table with RSU type UE
FFS: the generation of background channel based on reference TRs is subject to the addition of low-energy clusters



[Moderator’s note] Let’s check the following proposals on handling RSU type UE

[FL2] Proposal 5.1-2 
In order to generate Tx-target link, target-Rx link and the background channel between a RSU-type UE and another node (TRP, pedestrian UE, vehicle UE, RSU-type UE), the following reference TRs are adopted





[H] Parameter values to generated background channel for monostatic

Summary on company views

Nrp = 3: ZTE Corporation, Sanechips, OPPO, BUPT, BJTU, CAICT, Xiaomi, Huawei
Nrp = 1: SS, Apple

ZTE, et al.: Confirm the previous working assumption on background channel for mono-static sensing with the following details:
reference points are dropped for one Tx, based on the Gamma distribution for distance and height of reference point.
The LOS AOD between Tx and the first reference point is generated based on uniform distribution , and the gap of LOS AOD between the Tx and different reference points keeps as .
The background channel is generated based on the channel generated as in existing TR between the real Tx and the reference point in NLOS condition.
The antenna field pattern and array orientation of reference point are set same as Tx. 
Arrival angles for both azimuth and elevation  and  are set equal to departure angles, and coupled with the corresponding departure angles one by one.
The mono-static background channel for the Tx would be sum of channels of the links between the Tx and all related reference points, which is

ZTE et al. 
Proposal 2: For background channel of mono-static sensing, the distance between Tx and the reference point, and the height of the reference point follow parameterized Gamma distribution  with offset , and the related parameters in scenarios of UMa, UMi, RMa, Urban grid, Indoor-office,  and highway are given by:

Huawei: 
Proposal 12: The generation and parameters for the background channel for mono-static sensing can be modelled as:
Step1：deploy the reference points as:




The 3D coordinates of the reference points are:

Step 2: generate the clusters following the TR 38.901 generation steps under NLOS condition with modification as
number of clusters = 8.
SF = 2.5
the absolute delay for each cluster generated as

Step 3: Combine the channels of each BS-RP link.

ZTE, et al. 
Highway: The distribution of reference points of RMa is reused for Highway scenario.
Urban grid: The distribution of reference points of UMa is reused for urban grid scenario.
CATT
For the Mono-static target channel modelling, the determination of delay, angle, K factor and polarization matrix for Tx-target link and target-Rx link should follow the following rules:
Same K factor should be used for two separate links.
LOS AOA and LOS ZOA of target-Rx link should be the same as LOS AOD and LOS ZOD of Tx-target link.
LOS AOD and LOS ZOD of target-Rx link should be the same as LOS AOA and LOS ZOA of Tx-target link.
Delay spread, angle spread and polarization for the two separate links should be generated independently.
The ASA and ZSA of target-Rx link should obey the same statistical distribution characteristics of ASD and ZSD of Tx-target link, respectively.
The ASD and ZSD of target-Rx link should obey the same statistical distribution characteristics of ASA and ZSA of Tx-target link, respectively.
E//: Revert the working assumption from RAN1#120 and continue study Option 2 and Option 3 in the RAN1#118 agreement
Nokia: clutter map is proposed for the background channel


[Moderator’s note] Thanks for all companies working on the parameter values based on the working assumption from last meeting. A joint contribution is available which summarizes data for each sensing scenario. Additionally, a set of values are proposed by Huawei which seems well aligned with the joint tdoc, too. 

[FL1] Proposal 5.2-1
Confirm the previous working assumption on background channel for mono-static sensing with the following details:
 reference points are dropped for one Tx, based on the Gamma distribution for distance and height of reference point.
The LOS AOD between Tx and the first reference point is generated based on uniform distribution , and the gap of LOS AOD between the Tx and different reference points keeps as .
The background channel is generated based on the channel generated as in existing TR between the real Tx and the reference point assuming NLOS condition.
The antenna field pattern and array orientation of reference point are set same as Tx. 
Arrival angles for both azimuth and elevation  and  are set equal to departure angles
The absolute delay model  as agreed for bistatic sensing for the same sensing scenario applies. 
The mono-static background channel for the Tx would be sum of channels of the links between the Tx and all related reference points, which is



[FL1] Proposal 5.2-1-rev1
Confirm the previous working assumption on background channel for mono-static sensing with the following details:
 reference points are dropped for one Tx, based on the Gamma distribution for distance and height of reference point.
The LOS AOD between Tx and the first reference point is generated based on uniform distribution , and the gap of LOS AOD between the Tx and different reference points keeps as .
The background channel is generated based on the channel generated as in existing TR between the real Tx and the reference point assuming NLOS condition.
The antenna field pattern and array orientation of reference point are set same as Tx. 
Arrival angles for both azimuth and elevation  and  are set equal to departure angles
The absolute delay model d3D and  as agreed for bistatic sensing for the same sensing scenario applies. 
The mono-static background channel for the Tx would be sum of channels of the links between the Tx and all related reference points, which is

FFS: Doppler frequency in background channel for monostatic sensing
FFS: whether to add additional very low power clusters
FFS: any update to parameters e.g. angular distribution and delay spread


[Moderator’s note] Further revised based on online discussion and offline 
[FL2] Proposal 5.2-1-rev2
On background channel for mono-static sensing, the following details are provided:
 reference points are dropped for one Tx, based on the Gamma distribution for distance and height of reference point.
The LOS AOD between Tx and the first reference point, which is denoted as AOD1, is generated based on uniform distribution .
The LOS AOD between Tx and the second reference point is AOD1 + 
The LOS AOD between Tx and the third reference point is AOD1 + 
The background channel is generated based on the channel generated as in existing TR between the real Tx and the reference point assuming NLOS condition.
The antenna field pattern and array orientation of reference point are set same as Tx. 
Arrival angles for both azimuth and elevation  and  are set equal to departure angles
The absolute delay model [d3D and]  as agreed for bistatic sensing for the same sensing scenario applies. 
The mono-static background channel for the Tx would be sum of channels of the links between the Tx and all related reference points, which is

FFS: Doppler frequency in background channel for monostatic sensing
FFS: whether/howto add additional very low power clusters
FFS: any update to parameters e.g. angular distribution and delay spread



[Moderator’s note] As suggested by the joint contribution, the fitted data for Uma/Rma can be extended to Urban grid and highway. Some further observation from moderator are
For highway, it is derived by Rma for FR1, but is Uma for FR2
For HST, it is derived by Rma
Therefore, the moderator extends/revises the proposal from the joint contribution. Please check if the following proposal is agreeable. 

[FL1] Proposal 5.2-2
The values of the parameters to generated background channel for TRP monostatic sensing for each sensing scenario are provided in the following table 



[FL2 Proposal 5.2-2-rev2
The values of the parameters to generated background channel for TRP monostatic and UE monostatic sensing for each sensing scenario are provided in the following table 
FFS parameter values for other scenarios





[Moderator’s note] We already have agreement that large scale parameters are same for the Tx-target and target-Rx links for monostatic sensing. A remaining issue is the small scale parameters as discussed by CATT. For reciprocity, should we assume all small scale parameters are same for the Tx-target and target-Rx links?

[FL1] Proposal 5.2-3
The small scale parameters used to generate the Tx-target link are respectively same as that of the target-Rx link. 



[FL1] Proposal 5.2-3-rev1
The small scale parameters used to generate the Tx-target link are respectively same as that of the target-Rx link for monostatic sensing. 


[Moderator’s note] Agreement after Tuesday online
Agreement
To generate the parameters (in the steps before concatenation), the large-scale parameters and the small-scale parameters used to generate the Tx-target link are respectively the same as that of the target-Rx link for monostatic sensing, where departure angle on one link and arrival angle on the other link are reciprocal.
FFS: whether this applies to initial phase


[H] Polarization matrix normalization
Summary on company views

Whether/how normalization on the polarization of a direct/indirect path, i.e., CPMtx,sp,rx= CPMsp,rx . CPMsp . CPMtx,sp is supported? 
No: LG, Nokia, CAICT
Yes: ZTE, vivo, Samsung, Qualcomm, OPPO, HW, Apple, BUPT
: ZTE
: HW
diagonal-term normalization: QC, Apple
: vivo
: BUPT

Vivo: RAN1 determines whether the power normalization of CPM is necessary after CPM concatenation depends on the value of XPR for CPM of target.
The magnitude of the diagonal elements of each component CPMsp,rx , CPMsp , CPMtx,sp  should be set to 1: Apple

[Moderator’s note] The majority view is to have normalization. ZTE has results comparing different options for normalization and the conclusion is using absolute value is the best. Please check if you are OK with the following proposal. 

[FL1] Proposal 5.3-1 
Normalization on the product of three polarization matrixes of a direct/indirect path, i.e., CPMtx,sp,rx= CPMsp,rx . CPMsp . CPMtx,sp is supported
The scaling factor is 



[FL1] Proposal 5.3-1-rev1 
Normalization on the product of three polarization matrixes of a direct/indirect path, i.e., CPMtx,sp,rx= CPMsp,rx . CPMsp . CPMtx,sp is supported
The scaling factor is 


[Moderator’s note] Agreement in Tuesday online
Agreement
Normalization on the product of three polarization matrixes of a direct/indirect path generated by stochastic cluster, i.e., CPMtx,sp,rx= CPMsp,rx . CPMsp . CPMtx,sp is supported
The scaling factor is 


[H] Power threshold 

Summary on company views

Power threshold for path dropping after concatenation
-40dB: HW, Nokia, CATT, CMCC, OPPO, Xiaomi (-45 first), Apple, Spreadtrum
-25dB: LGE
Inf: QC, IDC

Removing a cluster from background channel referring to the maximum path power in target channel: LGE, Apple
IDC: Do not adopt path dropping after concatenation

Power normalization of target channel after path dropping
Not supported: HW, Xiaomi, Nokia, LGE, CMCC, Panasonic, Apple
Supported: SS, Tiami

Power threshold for cluster dropping for background channel 
The power threshold for cluster dropping in background channel can be discussed together with possible introduction of very low power clusters. 
Option 1: threshold = -25dB, no additional very low power clusters
LG(2nd), CATT, Xiaomi, Apple
Option 2: threshold < -25dB, no additional very low power clusters
HW (-40), Tejas(-Inf)
Option 3: threshold = -25dB, introducing additional very low power clusters
Nokia, ZTE, Lenovo
Option 4: threshold < -25dB, introducing additional very low power clusters
Nokia, ZTE, Lenovo, QC(-Inf)
Option 5: threshold = -25dB, removing a cluster from background channel referring to the maximum path power in target channel 
LG(1st), MTK

Add additional very low power clusters: QC, Lenovo, Tiami
QC, Tiami: Introduce a set of low-power clusters in the background channel which have a power that is in the order of the ISAC target channel’ sensing clusters
Lenovo: clutter with an energy of at least 7 dB [or a required SSNR value corresponding to a sensing task] below the energy of the target channel shall be modelled in the ISAC background/environment channel.
For the generation of the low-energy cluster/rays, [] = [40-240, 1], would be sufficient to obtain required dynamic range of the background channel for the bistatic sensing scenarios.

Huawei: The reference power for removing cluster can follow the TR38.901 without any other updates

Lenovo
For the generation of the low-energy cluster/rays, [] = [180-240, 1], would be sufficient to obtain required dynamic range of the background channel for both bistatic and monostatic sensing scenarios.
The stochastic clutter associated with an ISAC background channel can be odellin via the following steps:

[Moderator’s note] Based on the contributions, -40dB as the power threshold is agreeable
[FL2] Proposal 5.4-1 
Power threshold for path dropping after concatenation is -40dB for target channel



[Moderator’s note] There is clear common view that power normalization after path dropping is not necessary

[FL1] Proposal 5.4-2 
Power normalization of target channel after path dropping of the target channel is not supported


Agreement
Power normalization of target channel after path dropping of the target channel is not supported.


[Moderator’s note] The most straightforward way is to reuse the threshold -25dB in cluster dropping, which also maintains backward compatibility with communication. However, considering the analysis that the path in background channel may be much higher than a path in the target channel, a simple way to mitigate it is to lower the threshold for cluster dropping in Step 6 generating the background channel. Not dropping a cluster <-25dB will have neglectable impacts to communication (the reason why such cluster is dropped in exiting TR). Therefore, the moderator propose that we reduce the power threshold, e.g. Huawei suggests to use -40dB. 
[FL2] Proposal 5.4-3 
To generate the background channel, the power threshold for removing clusters in step 6 in section 7.5, TR 38.901 is -40 dB 



[Moderator’s note] Regarding the FFS point of additional very low power clusters, please proponent company provide your solution. It is good if the proponent can converge to a single option, otherwise it is hard to move forward. 

[FL1] Question 5.4-4 
Whether/how to model some lower power NLOS clusters in background channel beyond those generated by existing section 7.5, TR 38.901?


[FL2] Proposal 5.4-4 
The ISAC background channel can be generated between a sensing Tx and a sensing Rx or RP (relevant for monostatic case) via the following steps:
Step 1: generate a first set of clusters/rays according to TR 38.901
Step 2: generate a second set of NLOS clusters/rays according to TR 38.901, where the power of the second set of clusters/rays should be scaled down such that


(,   are the power of the n-th cluster from the first and second set, respectively).
FFS any modification from 38.901 for the second set including the number of clusters N, and the number of rays within each cluster M, value of G, the large scale statistics (for generation of the second set of clusters)
Example 0. G = -25dB
Example 1 N=360, M=1, G=0dB, with uniform delay and angle (for mono-static case)
Example 2 N=120, M=1, G = -25dB, no further change from 38.901
Note: the step 2 is an additional modeling component


[H] Impact of height of target on LOS probability or pathloss
Summary on company views

Breaking point distance
HW: When the path loss model of Umi, Uma and Rma scenario of TR38.901 is used for the target channel, only the  is applied in the target channel irrespective of the breakpoint distance.

[Moderator’s note] In general, the scattering point location for the target (human, vehicle, …) may be lower than the commonly used UT height, e.g., 1.5m. It mainly impacts LOS probability determination and pathloss calculation. A simple solution is to extend the application range of the formulas in the current TR. However, as discussed by several companies, some issues are found, hence some solutions are proposed. 

[FL2] Proposal 5.5-1 
For sensing scenario UMi, UMa, RMa, UMi-AV, UMa-AV and RMa-AV, the height of target is used to calculate the LOS probability and pathloss, regardless of the lower bound in the existing TRs that are referred to generate ISAC channel. 



[Moderator’s note] The possible issues caused by extending application range of hUT includes 1) low/negative distance of breaking point for Umi/Uma/Rma; 2) reduced LOS probability. Please provide your views on the favorite option. 

[FL1] Question 5.5-2 
Please provide your views/solutions on the following issues
Issue 1: Negative dBP result in using the large pathloss  when hUT is reduced to be less than 1m
Issue 2: LOS probability is reduced a lot for InF scenario when hUT is reduced


[FL2] Proposal 5.5-2 
In sensing scenario UMi, UMa, RMa, UMi-AV, UMa-AV and RMa-AV, the minimum d_BP is 10m. 



Power normalization between target channel and background channel

Summary on company views

Alt 1: Power normalization on both target channel and background channel
Lenovo, Apple, Nokia, CATT, LGE, OPPO, QC, CT, Spreadtrum
Alt 2: Only the power of the background channel is scaled down to make total power normalized
EURECOM, ZTE, IDC, OPPO
Alt 3: the target channel of a target will replace one cluster in the background channel
BUPT (indoor/outdoor scenarios), Panasonic

OPPO: The power normalization in combining the target channel(s) and background channel is formulated as a linear programming problem, solved as following. 
The power normalization coefficient for the background channel is 
The power normalization coefficient for a target channel is 
QC: Support the following power normalization between the target and the background channel:
, where  is such that 
BUPT: When combining the target and background channels, different options can be selected based on the scenario category or blockage situation:
Method 1: In UAV scenarios, directly superimpose the target and background channels (Option 1). In indoor/outdoor scenarios, remove background cluster c that are closest to the target in the angular domain and replace them with the target channel (Option 2-Alt 3). 
Method 2：Remove background clusters that are blocked by the target in the angular domain. The possibility of blockage is high in indoor and outdoor scenarios (Option 2-Alt 3) but relatively low in UAV scenarios (Option 1).

Whether/how to specify a condition to select Option 1 or 2
Yes: BUPT
No: CATT

[Moderator’s note] Given Option 2 for power normalization is already agreed in an earlier agreement, the moderator would like to check whether we could follow the majority view among the 3 alternatives on this issue. 
[FL1] Proposal 5.7-1 
Option 2-Alt 1, i.e., power normalization applied on both target channel and background channel, i.e.,  is adopted to normalize the power of ISAC channel, where  is such that  



[Moderator’s note] Regarding ‘FFS condition to select option, e.g. depending on scenario, sensing mode, number of target/EO type-2’, please provide your view on anything should be specified or not. 
[FL1] Question 5.7-2 
Companies are encouraged to provide views on whether/how to specify a condition to select Option 1 ‘no power normalization’ and Option 2 ‘with power normalization’ in the combination of target channel and background channel. 


Doppler of moving scatters

Summary on company views

Reuse 7.6.10: HW, LGE

OPPO: Maximum speed and ratio of moving scatters depends on scenarios. 
Speed of 95%-100% moving scatters follows uniform distribution between 0 and 180km/h for UAV case 
Speed of 95%-100% moving scatters is 0 for indoor case 
Speed of 50% moving scatters is 3-60km/h and speed of remaining moving scatters is 0 for UMa/UMi.
Samsung: Clarify the scope of mobility of stochastic clutters
SS: due to environmental effects such as wind-induced mobility or if there are other factors related to target channel modeling, such as target mobility.
E//
Option 1: Use the existing procedure in clause 7.6.10 in TR 38.901, which creates Doppler variations for a proportion p of the stochastic clusters in the background channel
require many new measurement campaigns
Option 2: Drop additional moving unintended targets and use the target channel model for each of these
Apple
FFS1: the maximum speed of moving scatterers should not exceed maximum speed of target, Tx or Rx
FFS2: the ratio of moving scatterers among all scatterers depends on evaluation goal.
BUPT
The Micro-Doppler may need to be considered in ISAC channel modelling, and the formula   can be used as a starting point for the modelling of the Micro-Doppler.

[Moderator’s note] Inputs on how to handle maximum speed and ratio for moving scatters are appreciated. 
[FL1] Question 5.8-1 
Companies are encouraged to provide inputs on the following FFS points. 
FFS: maximum speed of moving scatterers
FFS: ratio of moving scatterers among all scatterers


Micro-Doppler
Summary on company views

Specify function for micro-Doppler
Neutral: HW
Yes: Nokia, QC, OPPO, vivo
NO: LGE, EURECOM

UAV: QC, OPPO, IDC
Human: QC,vivo, OPPO, BUPT,IDC
Bird: OPPO

Panasonic: Discuss whether the micro-Doppler patterns are per target or per scattering point
E//: Since micro-Doppler is essential for distinguishing wanted and unwanted targets, methods to model micro-Doppler are needed for the completion of the Study Item.
OPPO:

Vivo
	Eq. 8
	Eq. 9

IDC
Table 2: Micro-Doppler functions for micro-motions of humans and UAVs.

Nokia: the micro-Doppler modeling shall be based on the dual mobility modeling of Section 7.6.10 of TR38.901 as baseline

[Moderator’s note] The following proposal should be agreeable. 
[FL1] Proposal 5.9-1
Micro-Doppler, if enabled, is generated per scattering point for a target.


[Moderator’s note] RAN1 already agreed on the placeholder for micro-Doppler. If there is remaining TU, it is nice to decide certain detailed functions to handle micro-Doppler
[FL1] Question 5.9-2
Companies are encouraged to input on the proper functions/models for micro-Doppler



Absolute delay


Summary on company views

Confirm the WA: Apple, ZTE
QC: Support the absolute time of arrival modelling for the highway and urban grid scenarios. At least for the urban grid scenario use the same parameter values as that from the UMi scenario for the TRP to UE links.
FFS: The parameter values for the highway scenario.
OPPO: Before RAN1 confirms the RAN1 #120 working assumption on absolute delay, RAN1 seeks for an agreement on a LOS scattering model with non-zero Δτ being applied, in order to retain a odelling feature that has already been agreed.

[Moderator’s note] From last meeting, the application of absolute delay in ISAC channel model is agreeable. The concern at that time is the parameter values for  may not be available. As discussed by OPPO, if the WA is confirmed, it means there is no case that absolute delay is not enabled. Consequently, the procedure in the early agreement will not happen. 
[FL2] Proposal 5.10-1 
The following working assumption is confirmed


[Moderator’s note] Following the discussion from QC, an observation is that the channel model for urban grid, highway and HST are derived based on Uma and/or Rma. Therefore, the moderator makes the following proposal. 

[FL2] Proposal 5.10-2 
To generate the absolute delay model for sensing scenarios Urban grid, highway and HST
For Urban grid, the values of parameters for  of scenarios UMa are reused. 
For Highway, the values of parameters for  of scenarios RMa and UMa are reused for FR1 and FR2 respectively. 
For HST, the values of parameters for  of scenarios RMa are reused. 


[FL1] Proposal 5.10-2-rev1 
To generate the absolute delay model for sensing scenarios Urban grid, highway and HST
For Urban grid, the values of parameters for  of scenarios UMa are reused. 
For Highway, the values of parameters for  of scenarios RMa and UMa are reused for FR1 and FR2 respectively. 
For HST, the values of parameters for  of scenarios RMa and UMa are reused for FR1 and FR2 respectively. 

EO type-2 
Huawei
When sensing target is modelled with multiple scattering points, 
The EO ray is generated per scattering point, i.e. Tx-EO-STsp-Rx, Tx-STsp-EO-Rx.
For concatenation with EO rays, the EO ray is concatenated with other rays as if it is a LOS ray.

Model arbitrary orientations of type 2 EOs: E//

E//: specular reflection is modelled, if Type-2 EO is of the same size as or larger than the first Fresnel zone. Otherwise, it is not modelled
The radius of the first Fresnel zone is approximately given by:

for tx—target distance d₁ and target—rx distance d₂, and wavelength λ.

EO type-2 in background channel
Summary on company views

EO type-2 in background channel if it is modelled in target channel
Yes: Huawei, Sony, ZTE, LGE, Lenovo, EURECOM, Spreadtrum
NO: Ericsson, DOCOMO, Nokia, CMCC, BUPT, QC, CATT, CICTCI, IDC
Neutral: Xiaomi

E//: 
Since stochastic clusters have been used to generate multipath propagation in UE-BS communication channel, the need for a deterministic Type-2 EO in the background channel is not clear.
the received power of the sensing Rx’s in the ISAC model with the absence of sensing targets would be different from that in the legacy UE-BS communication channel.

[Moderator’s note] A larger number of companies perfer to not model EO type-2 in background channel, but there is still quite a few companies prefer to have it. Therefore, the moderator would like to try a proposal in the middle, say the configuration of EO type-2 can be controlled separately for target channel and background channel. 
[FL2] Proposal 6.1-1 
EO type-2 is modeled in background channel as optional feature
Whether to model EO type-2 in target channel and background channel can be configured separately. 


[H] LOS condition considering EO type-2
Summary on company views

Option A: HW, Nokia, QC, BUPT, Panasonic, LGE, Samsung, HW, Nokia, ZTE, EURECOM, LGE, Xiaomi, Apple, Spreadtrum, CT, Sony, MTK, NVIDIA
The LOS probability equation defined in TR38.901: HW, Panasonic, Sony, EURECOM
Opiton B: Lenovo, CATT, IDC, DOCOMO, Ericsson, IDC, CATT, SK Telecom, Tejas
Type-2 EO has no impact on LOS/NLOS condition

Option A: HW, Nokia, QC, Panasonic, LGE, HW, Nokia, ZTE, EURECOM, LGE, [SS], Xiaomi, Apple, Spreadtrum, CT, Sony, MTK, NVIDIA
The LOS probability equation defined in TR38.901: HW, Panasonic, Sony, EURECOM
Opiton B: Lenovo, CATT, IDC, DOCOMO, Ericsson, IDC, CATT, Tejas
Type-2 EO has no impact on LOS/NLOS condition

HW: The EO type2 as a large and stationary building should not be defined as a blocker according to the blockage model in TR38.901.
E//: The legacy soft LOS state is applicable to ISAC channel model
E//: 
Option B is in line with existing procedure for blocking in TR 38.901, where the blocking does not change the LOS state.
With Option A, the spatial consistency between BS-target link and BS-UE channel is broken, when the target and UE are close to each other
Option A may cause a hard transition in the channel response as the targets moves, similar to UT movement, which legacy communication channel tries to avoid
Option A is more suitable for the map-based hybrid channel model or ray-tracing than the stochastic channel stated in section 7.5 of 38.901

[Moderator’s note] To make a complete proposal, Option A is revised based on the comments from proponent companies.  Please each company provide your preferred option. Down selection should be done in RAN1 #120bis.
[FL2] Proposal 6.2-1 
Down-select in RAN1#120bis one option from the following two options to determine the LOS condition of the Tx-target link and target-Rx link?
Option A: If type-2 EO is in the LOS ray of one link, the link is determined as NLOS condition, and otherwise use the LOS probability equation defined in existing TRs to determine the LOS/NLOS condition
FFS changes to the LOS probability defined in existing TRs
FFS details on blockage by EO type-2
Option B: Use the LOS probability equation to determine the LOS/NLOS condition of one link, and then the impacts of type-2 EO is modeled by a blockage model
Note: If EO type-2 is agreed to be modelled in background channel, the agreed option is extended to LOS conditioin determination for background channel. 


[H] EO type-2 for a link in NLOS condition
Summary on company views

ZTE: The pathloss of NLOS ray due to EO type 2 in the STX-SPST link or SPST-SRX link is calculated by , where  is the total propagation distance due to EO type2.
CATT: If EO type-2 is modelled when NLOS condition is determined for Tx-Target link or Target-Rx link:
The pathloss of Tx-Target link or Target-Rx link in NLOS condition with EO type-2 is calculated based on the LOS condition pathloss model
The channel impulse response equation of Tx-Target link or Target-Rx link in NLOS condition with EO type-2 should be modified as following:


[Moderator’s note] The existing behavior in 7.6.8, TR 38.901 assume the LOS ray is present, then power of ground reflection ray is calculated. The same principle is inherited for EO type-2 in LOS condition. As commented by some companies that EO type-2 is valuable for NLOS condition, the solution to calculate the path power is missing
[FL2] Question 6.3-1 
Please provide views on whether/how to model specular reflected ray of EO type-2 in a link with NLOS condition. 


Whether/how to normalize the power of target channel, background channel or the combined channel if EO type-2 is modeled?
Summary on company views

NO: Nokia, LG, vivo, CATT
Open: ZTE

[Moderator’s note] The existing behavior in 7.6.8 is to add the ground reflection ray without further power normalization. The number of EO type-2 may be large in a scenario, but number of strong EO type-2 that can be modeled for a link is always limited. Therefore, we may follow the existing behavior in 7.6.8, TR 38.901
[FL1] Proposal 6.4-1 
Additional power normalization is not considered due to the presence of EO type-2 
Note: this is aligned with the behaviour handling the power of a NLOS ray specular reflected by the ground in section 7.6.8, TS 38.901


Spatial consistency 
CATT: The existing spatial consistency model in TR 38.901 (i.e., site-specific correlation) is reused to model correlation of links between one RSU and different STs/UEs, instead of using the newly defined link correlation.
[H] General question
Is there correlation between the multiple points of a target if spatial consistency is NOT enabled?
Yes: Huawei?
HW: In Step 2 (i.e., the basic procedure), LOS/NLOS condition of the SPs within the same ST are correlated
No: vivo?

CATT
By default, initial random phase of target CPM remains unchanged even if target position changes during simulation. If spatial consistency is considered, initial random phase of target CPM may be further added in the correlation parameter list.

Concatenation Option 3 (1-by-1 random mapping of Tx-target and Tx-Rx link)
If concatenation Option 3 is used, should we update the set of generated paths during the movement of Tx, target and/or Rx?
NO: HW, Nokia, CATT, ZTE

Path dropping after concatenation of Tx-target and target-Rx link
Should we update the set of remaining paths after path dropping after concatenation during the movement of Tx, target and/or Rx?
NO: HW, CATT, ZTE

[Moderator’s note] Reading the contributions, it seems different companies have different understanding on default behavior when spatial consistency is not enabled. Let’s try to clarify it. 

[FL1] Question 7.1-1
When spatial consistency is NOT enabled, what are the understandings on the following questions?
Can we assume the Tx/target/Rx position is unchanged in a simulation drop?
Note: when position is unchanged, Tx/target/Rx velocity of Tx/target/Rx can still be modelled in the simulation, e.g., for Doppler
If changing the Tx/target/Rx position is supported, can we assume the large/small scale parameters of Tx-target link, target-Rx link and the background channel are regenerated independently?
If changing the Tx/target/Rx position is supported, can we assume the RCS component B2 and XPR/initial random phase of the target are regenerated independently?


[FL2] Proposal 7.1-1
When spatial consistency is NOT enabled, the Tx/target/Rx position is unchanged in a simulation drop



[Moderator’s note] When spatial consistency is enabled, the set of paths generated by concatenation Option 3 should not be updated during movement of Tx, target and/or Rx. Otherwise, the spatial consistency is broken. 

[FL1] Proposal 7.1-2 
When spatial consistency is enabled, the set of paths generated by concatenation Option 3 (1-by-1 random mapping) is not updated during movement of Tx, target and/or Rx. 


[FL2] Proposal 7.1-2-rev1 
When spatial consistency is enabled, the 1-by-1 random coupling generated by concatenation Option 3 is not updated during movement of Tx, target and/or Rx, if the LOS condition of the Tx-target and target-Rx links are not changed.




[Moderator’s note] When spatial consistency is enabled, the set of remaining paths after path dropping after concatenation of Tx-target and target-Rx link should not be updated during movement of Tx, target and/or Rx. Otherwise, the spatial consistency is broken. 
[FL2] Proposal 7.1-3 
When spatial consistency is enabled, the set of remaining paths after path dropping after concatenation of Tx-target and target-Rx link is not updated during movement of Tx, target and/or Rx. 


[H] Cases that spatial consistency are supported or not supported
Summary on company views



Whether to consider spatial consistency for the links that are generated referring to channel models with parameter values of different scenarios
E.g., between TRP-target/UT link in one scenario and target/UT-UT link in another scenario
Not modeled: HW, Nokia, LGE, vivo

Whether to consider spatial consistency for TRP-target/UT link and target/UT-UT link, if both links are referring to same scenario though the height of TRP and UE are different, e.g., UMi, InH, InF
Not modeled: HW, Nokia, BUPT
BUPT
f the height difference between the TRP and the UT/target is significant—as in UMi, UMa, RMa, Highway, and Urban grid scenarios—the statistical characteristics of the transmitter and receiver sides exhibit notable differences
if the target-UT link follows 38.858, the condition “ASD and ZSD statistics updated to be the same as ASA and ZSA for UE-UE” applies.
Support: LGE, vivo

[Moderator’s note] Based on the discussion in last meeting, it should be quite agreeable if the two links are generated using different parameter value sets of channel model. For background channel for TRP monostatic sensing, it is straightforward there is no spatial consistency for the virtual receivers/reference points of different TRPs 
[FL2] Proposal 7.2-1
Spatial consistency is not modelled for
the links that are generated referring to channel models with parameter values of different communication scenarios
E.g., between TRP-target/UT link in one scenario and target/UT-UT link in another scenario
the background channels for TRP monostatic sensing of different TRPs



[Moderator’s note] For sensing scenario UMi, InH and InF, it is likely we use the channel model referring the same communication scenario to generate TRP-UT/ST link and UT-ST/UT link. However, as discussed by BUPT, the ASD/ZSD may still be different for the two links. Therefore, it is proposed to not model spatial consistency for the links. 
[FL2] Proposal 7.2-2
Spatial consistency is not modelled between TRP-target/UT link and target/UT-UT link for sensing scenario UMi, InH and InF



[Moderator’s note] Then, it is a question, whether/how to model spatial consistency for the virtual receivers/reference points for UE monostatic sensing of different UEs or the same UE (mobility)?
[FL2] Question 7.2-3
Whether/how the spatial consistency for the background channels for UE monostatic sensing of different UEs or the same UE (mobility) can be supported? 
Please proponent company provide values of all necessary parameters for the model, e.g., the correlation distance, etc. 


Additional parameters to be considered for spatial consistency 

Summary on company views

Any additional parameters?
New parameter for Gamma distribution of background channel for monostatic sensing: ZTE
Note: this discussion is included in 7.1-3. Let’s start from checking whether it can be modelled and what is the solution and the required parameter values
No more: HW, Nokia, LGE, vivo

[Moderator’s note] As captured in the note of the agreement, RAN1 still need to check whether certain new parameters can be considered for the new spatial consistency model. In fact, this question is also applicable to the existing spatial consistency model which is reused for TRP-UE/ST links. Therefore, the moderator makes the following general question. 
[FL1] Question 7.3-1
Which new parameters should be considered for spatial consistency?


[H] Spatial consistency between multiple scattering points
Summary on company views

Huawei: Spatial consistency among multiple scattering points of the same target could be treated as different links.
BUPT
For targets such as small UAVs, large UAVs (in RMa and UMa scenarios), and humans, where the large-scale parameters between multiple points are highly correlated, it is recommended to reuse the spatial consistency results of a single point.
For targets such as vehicle Type 1, vehicle Type 3, and large UAVs (in UMi scenarios), it is recommended to model the spatial consistency for multiple points separately.
BUPT
We suggest calculating the fixed spatial decay coefficients between target multiple points beforehand. Once spatial consistency for any single point is calculated, apply these coefficients to efficiently and accurately model ISAC multi-point spatial consistency.

The multiple scattering points of a target are handled as if multiple targets with single scattering points
Yes: vivo, LGE


Should the correlation between multiple scattering points modelled by a spatial consistency procedure or other solution?

[FL2] Proposal 7.4-1
When spatial consistency is NOT enabled, channels of the multiple scattering points of a target are uncorrelated
Spatial consistency, if enabled, for the links between BS/UT and multiple scattering points of a target are modelled as if multiple targets with single scattering point. 



Solutions for new spatial consistency
Summary on company views

Any preference or more options?
Option 1: global grid (aka. Unified grid) + shifting UT/ST locations
ZTE, CATT, IDC
Option 2: direct modelling on the correlation of grids of different UT/ST, e.g., Cholesky decomposition
Vivo, LGE, SPRD
Option 3: direct modelling on the correlation of grids of different UT, e.g., Cholesky decomposition
Option 4: direct modelling on the correlation of grids of different ST, e.g., Cholesky decomposition

Vivo: The complexity reduction of target-specific method can be considered, e.g., by reducing the size of grid and using the combination of interpolation and extrapolation


[Moderator’s note] It is also important for us to try to align the understanding on exact solution to model spatial consistency for ST/UT links. 

Note: Intention is NOT to discuss the solution(s) for new spatial consistency ‘link-Correlated’ using offline/online session. 
[FL1] Proposal 7.5-1
Please provide details on the preferred solutions to the new spatial consistency model of ‘link-correlated’


[H] 3D spatial consistency
Summary on company views

3D spatial consistency
the existing 2D correlation distance in Table 7.6.3.1-2 in TR39.901 is extended to 3D correlation distance: vivo HW, Xiaomi, EURECOM, Nokia, LGE, CATT, ZTE, CMCC

Vivo: Model correction of target specific 3D grid by Cholesky decomposition of correlation matrix
E//: If spatial consistency in vertical plane is not supported by ISAC channel model, vertical mobility is not supported for UAV sensing

[Moderator’s note] Companies are encouraged to check if the following proposal is agreeable. 

[FL1] Proposal 7.6-1 
The existing 2D correlation distance in Table 7.6.3.1-2 in TR39.901 is reused as 3D correlation distance for ISAC channel at least for UAV scenario


[FL2] Proposal 7.6-1-rev1 
The existing horizontal correlation distance in Table 7.6.3.1-2 in TR38.901 is reused as vertical correlation distance for ISAC channel at least for UAV scenario


Procedure A vs. B for spatial consistency
Summary on company views

Can we concluded both spatial consistency procedures A and B in 7.6.3.2 in TR 38.901 are reused to support spatial consistency of ISAC channel STX/SRX/ST is/are moving?
Both: HW, Nokia, LGE, vivo, CATT, ZTE, CMCC (B is better). Tejas
A: Nokia, SPRD

[Moderator’s note] There is limited discussions from the contributions. However, since procedure A/B are supported in the existing 38.901, it may be supported by default, subjected to RAN1 discussions. Companies are encouraged to comment on the following proposal. 
[FL1] Proposal 7.7-1
Both spatial consistency procedures A and B in 7.6.3.2 in TR 38.901 are reused to support spatial consistency of ISAC channel STX/SRX/ST is/are moving

Link level channel model
Summary on company views

Option 1: Based on existing CDL channel model, 
Alt 1: add one or more clusters representing target(s): HW (parameters up to evaluation assumptions. A range can be defined), vivo, CATT, ZTE, BUPT

Alt 2: Update the parameters of one or more cluster to represent target(s)

Option 2: Reducing the system level channel model for ISAC to single Tx and single Rx: MTK

Parameter values for the target cluster to be decided in evaluation stage: Huawei
certain modification, e.g., the delay, angle, velocity or doppler parameter to the target cluster: vivo

Ericsson: For link-level ISAC channel models,
H_ISAC=H_target+H_background still holds.
legacy CDL models are reused to model Tx-target and target-Rx links of target channel and Tx-Rx channel of background channel.
target channel is generated by concatenating Tx-target and target-Rx link


[Moderator’s note] Companies are encouraged to comment on the following proposal. 

[FL1] Question 8.1-1  
Which option is preferred to model link-level channel for ISAC? 
Option 1: Based on existing CDL channel model, 
Alt 1: add one or more clusters representing target(s)
Alt 2: Update the parameters of one or more cluster to represent target(s)
Option 2: Reducing the system level channel model for ISAC to single Tx and single Rx
Option 3: The Tx-target link and target-Rx link are modelled by separate CDL channels, concatenation is then performed to get the target channel; the background channel is modelled by another CDL channel. 
Option 4: Not supported



[FL2] Proposal 8.1-1  
The link-level channel for ISAC is generated by adding add one or more clusters representing target(s) to the existing CDL channel model
Values of parameters of the added cluster(s) can be discussed in performance evaluation stage


Hybrid channel model
Summary on company views

ZTE: The procedure of hybrid channel modelling with RT simulation in TR 38.901 can be reused and enhanced for sensing. Specify the following typical maps and characteristics of sensing targets to align the simulation assumptions:
Urban grid map defined in 3GPP TR 37.885 
The well-known Manhattan map from open source
Indoor map defined in IEEE 802.11 WLAN
EM parameters defined for radar material by ITU 

[Moderator’s note] ZTE provides the modifications to incorporate ISAC channel model into the map-based hybrid channel model in existing TR 38.901. Companies are encouraged to comment on defining ISAC channel based on map-based hybrid channel model. 
[FL1] Question 9.1-1  
Please provide your view whether/how ISAC channel based on map-based hybrid channel model should be supported I Rel-19. If so, how to achieve it? 

3GPP TSG RAN WG1 #120bis			 R1-2502555
Wuhan, China, April 7th – 11th, 2025
Agenda item:	9.7.2
Source:	Moderator (Xiaomi)
Title:	Summary #3 on ISAC channel modelling
Document for:	Discussion/Decision

Proposal
The bistatic RCS of UAV with small size is modelled as
Component A: same as component A of mono-static RCS for UAV of small size
Component B1:  where  is the 3D bi-static angle between incident and scatter angle
Component B2: same as component B2 of mono-static RCS for UAV of small size


Proposed conclusion
No peak of bistatic RCS values is observed in the specular reflection direction for human.

[FL1] Proposal 7.6-1 
The existing 2D correlation distance in Table 7.6.3.1-2 in TR38.901 is reused as 3D correlation distance for ISAC channel at least for UAV scenario

[FL1] Proposal 7.1-2 
When spatial consistency is enabled, the set of paths generated by concatenation Option 3 (1-by-1 random mapping) is not updated during movement of Tx, target and/or Rx. 
Note: the values of delay, angle and power could be changed based on spatial consistency.


[FL1] Proposal 7.1-2 
When spatial consistency is enabled, the 1-by-1 random coupling generated by concatenation Option 3 is not updated during movement of Tx, target and/or Rx.


Wednesday (Apr. 9)

After Wednesday online 

Agreement
When spatial consistency is enabled, the 1-by-1 random coupling generated by concatenation Option 3 is not updated per simulation drop even if Tx, target, Rx positions change during simulation.


[FL2] Proposal 7.6-1-rev1 
The existing horizontal correlation distance in Table 7.6.3.1-2 in TR38.901 is reused as vertical correlation distance for ISAC channel at least for UAV scenario.


[FL2] Proposal 4.1.1-2-rev2
For vehicle with single/multiple scattering points, down select one option  generating bistatic RCS. 

Option C:
Define the following two functions


The values/pattern A*B1, denoted as  of the bistatic RCS for a SPST is determined by
A first peak of bi-static RCS centred in the back-scattering direction of the incident direction is calculated as

A second peak of bi-static RCS centred in the specular reflection direction of the incident angle is calculated as

, (it is a concave function) 
For the front of vehicle, k1 = 15, k2 = 1.65
For the back of vehicle, k1 = 17.5, k2 = 1.65
For the left or right of vehicle, k1 = 14.5, k2 = 1.55
For the roof of vehicle, FFS
 is within 0~180 degrees.  is the absolute angle between the incident angle and scattering angle within the plane of incident direction () and scattering direction ().
 is the specular reflection direction, 
The final bistatic RCS value for incident/scattered angles () is 
The effect of forward scattering  is -Inf in Rel-19
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs

Option D:
The values/pattern of A*B1 of bistatic RCS is given by:

	where


 is applied to the  within 0~180 degrees. k1= 6 and k2=1.  is the absolute angle between the incident and scattering within the plane of incident direction () and scattering direction ().
The angles of () are the projections of the bisector angle on the vertical plane and the horizontal plane, respectively.
FFS: bisector angle when  is 180 degrees
The effect of forward scattering  is -Inf in Rel-19
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs
FFS: how to avoid angular discontinuity


Agreement
The following working assumption is confirmed


Thursday (Apr. 10)

[FL3] Proposal 4.1.1-2-rev5 for working assumption
For vehicle with single/multiple scattering points, the bistatic RCS is generated by
Option D:
The values/pattern of A*B1 of bistatic RCS is given by:

	where


 is applied to the  within 0~180 degrees. k1= 6 and k2=1.  is the absolute bistatic angle between the incident and scattering within the plane of incident direction () and scattering direction ().
The angles of () are the projections of the bisector angle on the vertical plane and the horizontal plane, respectively.
FFS: bisector angle when  is 180 degrees
The effect of forward scattering  is -Inf in Rel-19
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs
FFS: how to avoid angular discontinuity
Continue study on a new formula for  to resolve the issue of angular discontinuity. 
The new formula should retain following property: the linear bistatic RCS for a vehicle with single scattering point is the sum of the bistatic RCS of the multiple scattering points of the vehicle
the following formula can be a reference for the study 

 

[FL3] Proposal 5.2-1-rev3
On background channel for mono-static sensing, the following details are provided:
 reference points are dropped for one Tx, based on the Gamma distribution for distance and height of reference point.
The LOS AOD between Tx and the first reference point, which is denoted as AOD1, is generated based on uniform distribution .
The LOS AOD between Tx and the second reference point is AOD1 + 
The LOS AOD between Tx and the third reference point is AOD1 + 
The background channel is generated based on the channel generated as in existing TR between the real Tx and the reference point assuming NLOS condition.
The antenna field pattern and array orientation of reference point are set same as Tx. 
Arrival angles for both azimuth and elevation  and  are set equal to departure angles
The absolute delay model d3D and  as agreed for bistatic sensing for the same sensing scenario applies. 
Option 1: A scaling factor d_s is applied to d3D. d_s is uniformly distributed with [0, 1] 
Option 2: A scaling factor d_s is applied to d3D. d_s = d3D-c1
Option 3: A scaling factor d_s is applied to d3D. d_s is within range [0, 1]. FFS value of d_s 
The mono-static background channel for the Tx would be sum of channels of the links between the Tx and all related reference points, which is

FFS: Doppler frequency in background channel for monostatic sensing
FFS: whether/howto add additional very low power clusters
FFS: any update to parameters e.g. angular distribution and delay spread
The rays in a stochastic cluster with ZOA at BS less than D degree are dropped [with probability p, p=1] 
D=[90] for RMa, 
D=[60] for UMa
Note: this threshold for ZOA is not applicable to other sensing scenarios


[FL3] Proposal 5.4-3 
To generate the background channel, the power threshold for removing clusters in step 6 in section 7.5, TR 38.901 is reused


[FL3] Proposal 5.4-4-rev1 
The ISAC background channel can be generated between a sensing Tx and a sensing Rx or RP (relevant for monostatic case) via the following steps:
Step 1: generate a first set of clusters/rays according to TR 38.901(or other related TRs)
Step 2: generate a second set of NLOS clusters/rays according to TR 38.901 (or other related TRs), where the power of the second set of clusters/rays should be scaled down such that


(,   are the power of the n-th cluster from the first and second set, respectively).
Where, N is the number of clusters, M is the number of rays within each cluster, value of G relates to power
Option 1: N=360, M=1, G=0dB, with uniform delay and angle (only for mono-static case)
Supported by: Nokia
Option 2: N=360, M=1, G = -25dB, no further change from 38.901, 36.777, 38.858 (i.e., utilizing the same DS, ASA, ASD, ZSA, ZSD, ,  as used for the first step)
Supported by: Xiaomi, ZTE, Lenovo, MTK, Qc, CMCC, IDCC, 
Note: the step 2 is an additional modeling component


[FL3] Proposal 5.2-2-rev3 for working assumption
The values of the parameters to generated background channel for TRP monostatic and UE monostatic sensing for each sensing scenario are provided in the following table 
FFS parameter values for other scenarios
An email discussion checking the values after April meeting are preferred, including newly agreed parameters




[FL3] Proposal 4.1.2-1 
The bistatic RCS of UAV with small size is modelled as
Component A: same as component A of mono-static RCS for UAV of small size
Component B1:  where  is the 3D bi-static angle between incident angle and scattered angle
Component B2: same as component B2 of mono-static RCS for UAV of small size


[FL3] Proposal 4.1.3-1 
The bistatic RCS of human with RCS model 1 is modelled as
Component A: same as component A of mono-static RCS for human with RCS model 1
Component B1:  where  is the 3D bi-static angle between incident angle and scattered angle
Component B2: same as component B2 of mono-static RCS for human with RCS model 1

[FL2] Proposal 5.10-2-rev1 
To generate the absolute delay model for sensing scenarios Urban grid, highway and HST
For Urban grid, the values of parameters for  of scenarios UMa are reused. 
For Highway, the values of parameters for  of scenarios RMa and UMa are reused for FR1 and FR2 respectively. 
For HST, the values of parameters for  of scenarios RMa and UMa are reused for FR1 and FR2 respectively. 


[FL3] Proposal 7.1-3-rev1 
When spatial consistency is enabled, the set of remaining paths after path dropping after concatenation of Tx-target and target-Rx link is not updated per simulation drop even if Tx, target, Rx positions change during simulation.


[FL3] Proposal 7.2-1
Spatial consistency is not modelled for
the links that are generated referring to channel models with parameter values of different communication scenarios
E.g., between TRP-target/UT link in one scenario and target/UT-UT link in another scenario
the background channels for TRP monostatic sensing of different TRPs


[FL3] Proposal 7.2-2
Spatial consistency is not modelled between TRP-target/UT link and target/UT-UT link for sensing scenario UMi, InH and InF


[FL3] Proposal 7.4-1
When spatial consistency is NOT enabled, channels of the multiple scattering points of a target are uncorrelated
Spatial consistency, if enabled, for the links between BS/UT and multiple scattering points of a target are modelled as if multiple targets with single scattering point. 


[FL3] Proposal 4.2.1-1 
On the monostatic RCS of UAV of large size,
The values/pattern of component A*B1 are generated by the following parameters 

When  is in the range [0°,45° ] or [135°,180°], 
The standard deviation of component B2 is 2.50 dB


[FL3] Proposal 4.2.3-1 
On the monostatic RCS of AGV with single scattering point,
The values/pattern of component A*B1 are generated by the following parameters 

When  is in the range [0°,30° ), 
The standard deviation of component B2 is 2.51 dB


[FL3] Proposal 8.1-1  
The link-level channel for ISAC is generated by adding add one or more clusters representing target(s) to the existing CDL channel model
Values of parameters of the added cluster(s) can be discussed in performance evaluation stage

Proposed offline proposals
Monday (Apr. 7)
After Monday offline session

[FL1] Proposal 5.1-1-rev1 
In order to generate Tx-target link, target-Rx link and the background channel, The above table on reference TRs (excluding the already agreed part) is adopted for the mapping between reference TRs and a pair of nodes (STX, SRX, target) 
FFS RSU type UE


[FL1] Proposal 5.2-1-rev1
Confirm the previous working assumption on background channel for mono-static sensing with the following details:
 reference points are dropped for one Tx, based on the Gamma distribution for distance and height of reference point.
The LOS AOD between Tx and the first reference point is generated based on uniform distribution , and the gap of LOS AOD between the Tx and different reference points keeps as .
The background channel is generated based on the channel generated as in existing TR between the real Tx and the reference point assuming NLOS condition.
The antenna field pattern and array orientation of reference point are set same as Tx. 
Arrival angles for both azimuth and elevation  and  are set equal to departure angles
The absolute delay model [d3D and]  as agreed for bistatic sensing for the same sensing scenario applies. 
The mono-static background channel for the Tx would be sum of channels of the links between the Tx and all related reference points, which is

FFS: Doppler frequency in background channel for monostatic sensing
FFS: whether to add additional very low power clusters
FFS: any update to parameters e.g. angular distribution and delay spread


[FL1] Proposal 5.2-2-rev2
The values of the parameters to generated background channel for TRP monostatic and UE monostatic sensing for each sensing scenario are provided in the following table 
FFS parameter values for other scenarios


[FL1] Proposal 5.2-3-rev1
The small scale parameters used to generate the Tx-target link are respectively same as that of the target-Rx link for monostatic sensing. 

[FL1] Proposal 5.3-1-rev1 
Normalization on the product of three polarization matrixes of a direct/indirect path, i.e., CPMtx,sp,rx= CPMsp,rx . CPMsp . CPMtx,sp is supported
The scaling factor is 

[FL1] Proposal 5.4-2 
Power normalization of target channel after path dropping of the target channel is not supported

[FL1] Proposal 4.2.2-1-rev1 
On the monostatic RCS for human with RCS model 2
The monostatic RCS for a scattering point of the target is generated by
The values/pattern A*B1, i.e.,  is deterministic based on incident/scattered angles

Where,


FFS how many rows of the values/pattern A*B1 are defined for the target
Note: each row has a defined applicable range of  and 
Note: whether the RCS is elevation angle dependent or dependent on both elevation and horizontal angles can be separately discussed


[FL1] Proposal 4.5-1 
The following mean and standard deviation values of XPR of targets are agreed
UAV: (13.75, 7.07) dB
Human: (19.81, 4.25) dB
Vehicle: (21.12, 6.88) dB


[FL1] Proposal 4.1.1-2-rev1
For vehicle with single/multiple SPSTs, down select one option from the following options generating bistatic RCS. 
Option A:
The values/pattern of A*B1 of bistatic RCS is given by:

	where


 is applied to the  within 0~180 degrees. The k= 6 based on the measurement validation.  is the absolute angle between the incident angle and scattering angle within the plane of incident direction () and scattering direction ().
The angles of () are the projections of the bisector angle on the vertical plane and the horizontal plane, respectively.
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs
Supported by: Huawei, CATT, ZTE, Xiaomi, OPPO

Option B:
Define the following two functions


The values/pattern A*B1, denoted as  of the bistatic RCS for a SPST is determined by
A first peak of bi-static RCS centred in the back-scattering direction of the incident direction is calculated as

A second peak of bi-static RCS centred in the specular reflection direction of the incident angle is calculated as

, (it is a concave function) 
For the front of vehicle, k1 = 15, k2 = 1.65
For the back of vehicle, k1 = 17.5, k2 = 1.65
For the left or right of vehicle, k1 = 14.5, k2 = 1.55
For the roof of vehicle, FFS
 is within 0~180 degrees.  is the absolute angle between the incident angle and scattering angle within the plane of incident direction () and scattering direction ().
 is the specular reflection direction, 
The final bistatic RCS value for incident/scattered angles () is 
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs
Supported by: vivo, BUPT, ZTE, CMCC, DOCOMO 

Option C:
Define the following two functions


The values/pattern A*B1, denoted as  of the bistatic RCS for a SPST is determined by
A first peak of bi-static RCS centred in the back-scattering direction of the incident direction is calculated as

A second peak of bi-static RCS centred in the specular reflection direction of the incident angle is calculated as

, (it is a concave function) 
For the front of vehicle, k1 = 15, k2 = 1.65
For the back of vehicle, k1 = 17.5, k2 = 1.65
For the left or right of vehicle, k1 = 14.5, k2 = 1.55
For the roof of vehicle, FFS
 is within 0~180 degrees.  is the absolute angle between the incident angle and scattering angle within the plane of incident direction () and scattering direction ().
 is the specular reflection direction, 
The final bistatic RCS value for incident/scattered angles () is 
 is -Inf in Rel-19
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs
Supported by: vivo, LGE, QC, BUPT, 


[FL1] Proposal 4.1.1-1
No special handling of RCS values in the forward scattering directions in Rel-19 SI
The existing blockage model B is reused to model the blocking effect due to a target as an optional feature 
Applicable to the LOS/NLOS rays in the background channel of the target

Tuesday (Apr. 8)
After Tuesday offline session

[FL1] Proposal 4.1.1-2-rev2
For vehicle with single/multiple SPSTs, down select one option from the following options generating bistatic RCS. 
Option A:
The values/pattern of A*B1 of bistatic RCS is given by:

	where


 is applied to the  within 0~180 degrees. The k= 6 based on the measurement validation.  is the absolute angle between the incident angle and scattering angle within the plane of incident direction () and scattering direction ().

The angles of () are the projections of the bisector angle on the vertical plane and the horizontal plane, respectively.
 is -Inf in Rel-19
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs
Supported by: Huawei, CATT, ZTE, Xiaomi, OPPO, LGE, Samsung, Nokia, 

Option B:
Define the following two functions


The values/pattern A*B1, denoted as  of the bistatic RCS for a SPST is determined by
A first peak of bi-static RCS centred in the back-scattering direction of the incident direction is calculated as

A second peak of bi-static RCS centred in the specular reflection direction of the incident angle is calculated as

, (it is a concave function) 
For the front of vehicle, k1 = 15, k2 = 1.65
For the back of vehicle, k1 = 17.5, k2 = 1.65
For the left or right of vehicle, k1 = 14.5, k2 = 1.55
For the roof of vehicle, FFS
 is within 0~180 degrees.  is the absolute angle between the incident angle and scattering angle within the plane of incident direction () and scattering direction ().
 is the specular reflection direction, 
The final bistatic RCS value for incident/scattered angles () is 
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs
Supported by: vivo, BUPT, ZTE, CMCC, DOCOMO 

Option C:
Define the following two functions


The values/pattern A*B1, denoted as  of the bistatic RCS for a SPST is determined by
A first peak of bi-static RCS centred in the back-scattering direction of the incident direction is calculated as

A second peak of bi-static RCS centred in the specular reflection direction of the incident angle is calculated as

, (it is a concave function) 
For the front of vehicle, k1 = 15, k2 = 1.65
For the back of vehicle, k1 = 17.5, k2 = 1.65
For the left or right of vehicle, k1 = 14.5, k2 = 1.55
For the roof of vehicle, FFS
 is within 0~180 degrees.  is the absolute angle between the incident angle and scattering angle within the plane of incident direction () and scattering direction ().
 is the specular reflection direction, 
The final bistatic RCS value for incident/scattered angles () is 
 is -Inf in Rel-19
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs
Supported by: vivo, LGE, QC, BUPT, CMCC, DOCOMO, ZTE

Wednesday (Apr. 9)

After Wed offline session

[FL2] Proposal 4.1.1-2-rev3
For vehicle with single/multiple scattering points, down select one option  generating bistatic RCS. 

Option C:
Define the following two functions


The values/pattern A*B1, denoted as  of the bistatic RCS for a SPST is determined by
A first peak of bi-static RCS centred in the back-scattering direction of the incident direction is calculated as

A second peak of bi-static RCS centred in the specular reflection direction of the incident angle is calculated as

, (it is a concave function) 
For the front of vehicle, k1 = 15, k2 = 1.65
For the back of vehicle, k1 = 17.5, k2 = 1.65
For the left or right of vehicle, k1 = 14.5, k2 = 1.55
For the roof of vehicle, FFS
 is within 0~180 degrees.  is the absolute angle between the incident angle and scattering angle within the plane of incident direction () and scattering direction ().
 is the specular reflection direction, 
The final bistatic RCS value for incident/scattered angles () is 
The effect of forward scattering  is -Inf in Rel-19
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs


Option D:
The values/pattern of A*B1 of bistatic RCS is given by:

	where


 is applied to the  within 0~180 degrees. k1= 6 and k2=1.  is the absolute bistatic angle between the incident and scattering within the plane of incident direction () and scattering direction ().
The angles of () are the projections of the bisector angle on the vertical plane and the horizontal plane, respectively.
FFS: bisector angle when  is 180 degrees
The effect of forward scattering  is -Inf in Rel-19
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs
FFS: how to avoid angular discontinuity


Method 1：
To address the issue of discontinuity, 

where：




Finally, the formula can be simplified to:


Method 2：


where：



[FL2] Proposal 5.2-1-rev2
On background channel for mono-static sensing, the following details are provided:
 reference points are dropped for one Tx, based on the Gamma distribution for distance and height of reference point.
The LOS AOD between Tx and the first reference point, which is denoted as AOD1, is generated based on uniform distribution .
The LOS AOD between Tx and the second reference point is AOD1 + 
The LOS AOD between Tx and the third reference point is AOD1 + 
The background channel is generated based on the channel generated as in existing TR between the real Tx and the reference point assuming NLOS condition.
The antenna field pattern and array orientation of reference point are set same as Tx. 
Arrival angles for both azimuth and elevation  and  are set equal to departure angles
The absolute delay model d3D and  as agreed for bistatic sensing for the same sensing scenario applies. 
The mono-static background channel for the Tx would be sum of channels of the links between the Tx and all related reference points, which is

FFS: Doppler frequency in background channel for monostatic sensing
FFS: whether/howto add additional very low power clusters
FFS: any update to parameters e.g. angular distribution and delay spread



[FL2] Proposal 5.4-3 
To generate the background channel, the power threshold for removing clusters in step 6 in section 7.5, TR 38.901 is reused


[FL2] Proposal 5.4-4-rev1 
The ISAC background channel can be generated between a sensing Tx and a sensing Rx or RP (relevant for monostatic case) via the following steps:
Step 1: generate a first set of clusters/rays according to TR 38.901(or other related TRs)
Step 2: generate a second set of NLOS clusters/rays according to TR 38.901 (or other related TRs), where the power of the second set of clusters/rays should be scaled down such that


(,   are the power of the n-th cluster from the first and second set, respectively).
Where, N is the number of clusters, M is the number of rays within each cluster, value of G relates to power
Option 1: N=360, M=1, G=0dB, with uniform delay and angle (only for mono-static case)
Supported by: Nokia
Option 2: N=60, M=1, G = -25dB, no further change from 38.901 (i.e., utilizing the same DS, ASA, ASD, ZSA, ZSD, ,  as used for the first step)
Supported by: Xiaomi, ZTE, Lenovo, MTK, Qc, CMCC, IDCC, 
Note: the step 2 is an additional modeling component


[FL2] Proposal 5.2-2-rev2 for working assumption
The values of the parameters to generated background channel for TRP monostatic and UE monostatic sensing for each sensing scenario are provided in the following table 
FFS parameter values for other scenarios
An email discussion checking the values are preferred



Thursday (Apr. 10)


Physical object model
E//: Angle-dependent RCS model of a target is provided for a given target’s local coordinate system
[H] Bistatic RCS
General on bistatic RCS

Summary on company views

Design issues on bistatic RCS
Whether/how to model a peak in the specular reflection direction (RCS_s())?
Yes: QC, E//, NIST, vivo, BUPT, ZTE, Xiaomi, Spreadtrum
What is the trend of the peak values with the change of incident direction?
roughly monotone: HW, ZTE
concave function: vivo, BUPT 
Whether/how to model a peak of the back scattering in the incident direction, which is equal to the monostatic RCS in the incident direction (RCS_i())?
Yes: QC, vivo, BUPT
Whether/how to model a shadow or peak in the forward scattering region?
peak: QC, LGE, vivo, BUPT, Apple
shadow: QC, HW, NIST, ZTE, 
To combine all the bi-static RCS components, select the bi-static RCS component with the maximum RCS value, : vivo, BUPT

CATT: min{,  RCS_MIN}
CT, LGE: 
Nokia
For bistatic RCS, use the bistatic angle to define at least two angular regions.
When bistatic angle , the bistatic RCS , at least , where  is monostatic RCS value.
When  is close to 180 degree, further study how to model bistatic RCS with forward scattering links.
LGE: 3 angular regions
LGE: Model the forward scattering RCS as a deterministic function , where angles  are determined w.r.t. the Tx to target line, Daz and Del are the effective extents of sensing target in azimuth and elevation domains, respectively. Define the angular width of the forward scattering region centered at  as  [rad].
E//: The bistatic RCS model should have a small, close-to-zero value in the forward scattering region if shadowing of the object is modelled using a blocker.

Shadows behind targets
Shadows behind targets should be odellin: Ericsson
Shadow is distance dependent: Ericsson

Ericsson: sensing Rx is likely to locate in the near field of a large target, where shadow effect needs to be taken into account

To model a shadow
large RCS in the shadow region than in other directions and with opposite phase to that of background channel so that H_target≈-H_background and H_ISAC=H_background+H_target becomes small
Ericsson
conflict with the agreement on scalar RCS odelling
without phase, it creates an energy increase behind the target, which breaks the laws of physics
The RCS needs to be dependent on both Tx-target distance and target-Rx distance to generate the correct “depth” of the shadow
Blockage model so that  is reduced in the shadow region: E//, NIST
E//: Blocking can simplify RCS modelling tremendously. Without the very strong forward scattering component, RCS is much easier to model
E//, Lenovo: The blockage of one target can be considered in the Tx-target and/or target-Rx links of another target channel depending on sensing mode.

NIST: We should explore how to model forward-scattering beyond shadowing region. Option 1: Continue using the blockage model, which models the combined behaviour of LOS and diffraction paths. Option 2: Use an effective RCS model based on target diffraction paths to reduce modelling complexity.

Diffraction / blockage model
The existing blockage model B is reused to model the blocking effect due to a target as an optional feature
Applicable to the LOS/NLOS rays in the background channel of the target
Applicable to the LOS/NLOS rays in the Tx-target and target-Rx link of the other target
Supported by: Ericsson, Lenovo, IDC, SONY, BUPT, DOCOMO, NIST
OK for optional feature: HW, Nokia, LGE, CATT, Samsung, QC
NO: vivo, ZTE

NVIDIA: blockage and forward scattering between sensing targets should be modelled in the target channel

Reciprocity
E//: The modelled RCS should be reciprocal 

[Moderator’s note] It is quite controversial whether/how to model diffraction/forward scattering. Some validation results show it is a peak in the forward scattering region, while other validation results indicate it is a shadow. The proposal on modeling a peak or a shadow is also diverged. The reason for the different measurements may be due to the assumed target to receiver distance. 
Considering the limited remaining Tus of the study item, it is generally not preferred to model distance dependent RCS for diffraction/forward scattering. 
As discussed by Ericsson and NIST, modelling a large RCS for forward scattering results in high total power received at the receiver, since the LOS ray in the background channel is modelled in the ISAC channel too. Given blockage model B can serve the purpose to model diffraction, we may not pursue a special handling on RCS for forward scattering in the limited remaining time for study. 
[FL1] Proposal 4.1.1-1
No special handling of RCS values in the forward scattering directions in Rel-19 SI
The existing blockage model B is reused to model the blocking effect due to a target as an optional feature 
Applicable to the LOS/NLOS rays in the background channel of the target


[Moderator’s note] Based on the companies’ inputs, the following two options (mainly for vehicle) get some supports. Both options have the following merits
The bistatic RCS for the backscatter of incident direction is equal to the monostatic RCS in the same direction
It generates a peak at the specular reflection direction
Both options will generate one peak at the backscatter of incident direction, up to 3 peaks for specular reflection since an incident ray can luminate up to 3 surfaces of the vehicle, e.g., front/left/roof for a transmitter in left-front direction with 
Note: for easy discussion, I now rename the following two options as Option A and Option B. 

For Option B, please provide your view on Alt 1 and Alt 2 to generate the peak RCS values of specular reflection direction. Alt 1 is originally proposed by vivo/BUPT, while Alt 2 is added by the moderator to align Option A/B. Not sure if Alt 2 can be a compromise since it uses a spirit of Option A. Other alternatives are not precluded at the moment. 

[FL1] Proposal 4.1.1-2
For vehicle with single/multiple SPSTs, down select one option from the following options generating bistatic RCS. 
Option A:
The values/pattern of A*B1 of bistatic RCS is given by:

	where
,
.
 is applied to the  within 0~180 degrees. The k= 6 based on the measurement validation.  is the absolute angle between the incident angle and scattering angle within the plane of incident direction () and scattering direction ().
The angles of () are the projections of the bisector angle on the vertical plane and the horizontal plane, respectively.
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs

Option B:
Define the following two functions


The values/pattern A*B1, denoted as  of the bistatic RCS for a SPST is determined by
A first peak of bi-static RCS centred in the back-scattering direction of the incident direction is calculated as

A second peak of bi-static RCS centred in the specular reflection direction of the incident angle is calculated as

Alt 1: , (it is a concave function) 
For the front of vehicle, k1 = 15, k2 = 1.65
For the back of vehicle, k1 = 17.5, k2 = 1.65
For the left or right of vehicle, k1 = 14.5, k2 = 1.55
For the roof of vehicle, FFS
Alt 2:  (decreasing with increased bistatic angles)
The k= 6 based on the measurement validation.
 is within 0~180 degrees.  is the absolute angle between the incident angle and scattering angle within the plane of incident direction () and scattering direction ().
 is the specular reflection direction, 
The final bistatic RCS value for incident/scattered angles () is 
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs



[FL1] Proposal 4.1.1-2-rev1
For vehicle with single/multiple SPSTs, down select one option from the following options generating bistatic RCS. 
Option A:
The values/pattern of A*B1 of bistatic RCS is given by:

	where


 is applied to the  within 0~180 degrees. The k= 6 based on the measurement validation.  is the absolute angle between the incident angle and scattering angle within the plane of incident direction () and scattering direction ().
The angles of () are the projections of the bisector angle on the vertical plane and the horizontal plane, respectively.
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs
Supported by: Huawei, CATT, ZTE, Xiaomi, OPPO

Option B:
Define the following two functions


The values/pattern A*B1, denoted as  of the bistatic RCS for a SPST is determined by
A first peak of bi-static RCS centred in the back-scattering direction of the incident direction is calculated as

A second peak of bi-static RCS centred in the specular reflection direction of the incident angle is calculated as

, (it is a concave function) 
For the front of vehicle, k1 = 15, k2 = 1.65
For the back of vehicle, k1 = 17.5, k2 = 1.65
For the left or right of vehicle, k1 = 14.5, k2 = 1.55
For the roof of vehicle, FFS
 is within 0~180 degrees.  is the absolute angle between the incident angle and scattering angle within the plane of incident direction () and scattering direction ().
 is the specular reflection direction, 
The final bistatic RCS value for incident/scattered angles () is 
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs
Supported by: vivo, BUPT, ZTE, CMCC, DOCOMO 

Option C:
Define the following two functions


The values/pattern A*B1, denoted as  of the bistatic RCS for a SPST is determined by
A first peak of bi-static RCS centred in the back-scattering direction of the incident direction is calculated as

A second peak of bi-static RCS centred in the specular reflection direction of the incident angle is calculated as

, (it is a concave function) 
For the front of vehicle, k1 = 15, k2 = 1.65
For the back of vehicle, k1 = 17.5, k2 = 1.65
For the left or right of vehicle, k1 = 14.5, k2 = 1.55
For the roof of vehicle, FFS
 is within 0~180 degrees.  is the absolute angle between the incident angle and scattering angle within the plane of incident direction () and scattering direction ().
 is the specular reflection direction, 
The final bistatic RCS value for incident/scattered angles () is 
 is -Inf
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs
Supported by: vivo, LGE, QC, BUPT, 


[Moderator’s note] Further revised based on offline discussions

[FL2] Proposal 4.1.1-2-rev2
For vehicle with single/multiple SPSTs, down select one option from the following options generating bistatic RCS. 
Option A:
The values/pattern of A*B1 of bistatic RCS is given by:

	where


 is applied to the  within 0~180 degrees. The k= 6 based on the measurement validation.  is the absolute angle between the incident angle and scattering angle within the plane of incident direction () and scattering direction ().
The angles of () are the projections of the bisector angle on the vertical plane and the horizontal plane, respectively.
The effect of forward scattering  is -Inf in Rel-19
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs
Supported by: Huawei, CATT, ZTE, Xiaomi, OPPO, LGE, Samsung, Nokia, 

Option B:
Define the following two functions


The values/pattern A*B1, denoted as  of the bistatic RCS for a SPST is determined by
A first peak of bi-static RCS centred in the back-scattering direction of the incident direction is calculated as

A second peak of bi-static RCS centred in the specular reflection direction of the incident angle is calculated as

, (it is a concave function) 
For the front of vehicle, k1 = 15, k2 = 1.65
For the back of vehicle, k1 = 17.5, k2 = 1.65
For the left or right of vehicle, k1 = 14.5, k2 = 1.55
For the roof of vehicle, FFS
 is within 0~180 degrees.  is the absolute angle between the incident angle and scattering angle within the plane of incident direction () and scattering direction ().
 is the specular reflection direction, 
The final bistatic RCS value for incident/scattered angles () is 
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs
Supported by: vivo, BUPT, ZTE, CMCC, DOCOMO 

Option C:
Define the following two functions


The values/pattern A*B1, denoted as  of the bistatic RCS for a SPST is determined by
A first peak of bi-static RCS centred in the back-scattering direction of the incident direction is calculated as

A second peak of bi-static RCS centred in the specular reflection direction of the incident angle is calculated as

, (it is a concave function) 
For the front of vehicle, k1 = 15, k2 = 1.5
For the back of vehicle, k1 = 17.5, k2 = 1.65
For the left or right of vehicle, k1 = 14.5, k2 = 1.55
For the roof of vehicle, 
 is within 0~180 degrees.  is the absolute angle between the incident angle and scattering angle within the plane of incident direction () and scattering direction ().
 is the specular reflection direction, 

The final bistatic RCS value for incident/scattered angles () is 
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs
Supported by: vivo, LGE, QC, BUPT, CMCC, DOCOMO, ZTE



[FL2] Proposal 4.1.1-2-rev3
For vehicle with single/multiple scattering points, down select one option  generating bistatic RCS. 

Option C:
Define the following two functions


The values/pattern A*B1, denoted as  of the bistatic RCS for a SPST is determined by
A first peak of bi-static RCS centred in the back-scattering direction of the incident direction is calculated as

A second peak of bi-static RCS centred in the specular reflection direction of the incident angle is calculated as

, (it is a concave function) 
For the front of vehicle, k1 = 15, k2 = 1.65
For the back of vehicle, k1 = 17.5, k2 = 1.65
For the left or right of vehicle, k1 = 14.5, k2 = 1.55
For the roof of vehicle, FFS
 is within 0~180 degrees.  is the absolute angle between the incident angle and scattering angle within the plane of incident direction () and scattering direction ().
 is the specular reflection direction, 
The final bistatic RCS value for incident/scattered angles () is 
The effect of forward scattering  is -Inf in Rel-19
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs


Option D:
The values/pattern of A*B1 of bistatic RCS is given by:

	where


 is applied to the  within 0~180 degrees. k1= 6 and k2=1.  is the absolute bistatic angle between the incident and scattering within the plane of incident direction () and scattering direction ().
When the β is 180 degrees, the bi-static RCS value is the minimum value from the bi-static RCS pattern, i.e., G_max-σ_max-k.
The angles of () are the projections of the bisector angle on the vertical plane and the horizontal plane, respectively.
FFS: bisector angle when  is 180 degrees
The effect of forward scattering  is -Inf in Rel-19
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs
FFS: how to avoid angular discontinuity


[Moderator’s note] Revised in Wed offline session. Note: I now merge method 1 proposed by BUPT to the procedure of Option D and name it as Option D2 for conveniency. Let’s wait for validation results and comments. 
[FL3] Proposal 4.1.1-2-rev4
For vehicle with single/multiple scattering points, down select one option between option D and D2 for generating bistatic RCS. 

Option D:
The values/pattern of A*B1 of bistatic RCS is given by:

	where


 is applied to the  within 0~180 degrees. k1= 6 and k2=1.  is the absolute bistatic angle between the incident and scattering within the plane of incident direction () and scattering direction ().
The angles of () are the projections of the bisector angle on the vertical plane and the horizontal plane, respectively.
FFS: bisector angle when  is 180 degrees
The effect of forward scattering  is -Inf in Rel-19
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs
FFS: how to avoid angular discontinuity


Option D2
The values/pattern of A*B1 of bistatic RCS is given by:

where：



Finally, the formula can be simplified to:

 is applied to the  within 0~180 degrees.  is the absolute bistatic angle between the incident and scattering within the plane of incident direction () and scattering direction ().
The angles of () are the projections of the bisector angle on the vertical plane and the horizontal plane, respectively.
FFS: bisector angle when  is 180 degrees
The effect of forward scattering  is -Inf in Rel-19
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs
FFS: how to avoid angular discontinuity


[FL3] Proposal 4.1.1-2-rev5 for working assumption
For vehicle with single/multiple scattering points, the bistatic RCS is generated by
Option D:
The values/pattern of A*B1 of bistatic RCS is given by:

	where


 is applied to the  within 0~180 degrees. k1= 6 and k2=1.  is the absolute bistatic angle between the incident and scattering within the plane of incident direction () and scattering direction ().
The angles of () are the projections of the bisector angle on the vertical plane and the horizontal plane, respectively.
FFS: bisector angle when  is 180 degrees
The effect of forward scattering  is -Inf in Rel-19
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs
FFS: how to avoid angular discontinuity
Continue study on a new formula for  to resolve the issue of angular discontinuity. 
The new formula should retain following property: the linear bistatic RCS for a vehicle with single scattering point is the sum of the bistatic RCS of the multiple scattering points of the vehicle
the following formula can be a reference for the study 

 

[Moderator’s note] Multiple companies propose that there is no specular reflection for human. One company prefer to model specular reflection for human. But please check if the proposal based on majority view is acceptable. 
[FL2] Proposal 4.1.1-3 for conclusion
No peak of bistatic RCS values is observed in the specular reflection direction for human



[Moderator’s note] For blockage model B, the proponents propose it not only for background channel, but also for interaction between targets. This is the second part of the proposal. Please check if it is agreeable. 
[FL1] Proposal 4.1.1-4 
The existing blockage model B is reused to model the blocking effect due to a target as an optional feature
Applicable to the LOS/NLOS rays in the Tx-target and target-Rx link of the other target



Framework/values for UAV
Summary on company views


CMCC


BUPT, vivo
The bi-static and mono-static RCS model share the same mathematical model at least for small UAV and human.

[Moderator’s note] Better to check if more inputs are available. 

[FL1] Question 4.1.2-1 
If any new results are available, please provide your inputs on values/pattern of A*B1 and (mean, standard deviation) of B2 for UAV of small size


[FL3] Proposal 4.1.2-1 
The bistatic RCS of UAV with small size is modelled as
Component A: same as component A of mono-static RCS for UAV of small size
Component B1:  where  is the 3D bi-static angle between incident angle and scattered angle
Component B2: same as component B2 of mono-static RCS for UAV of small size



[FL1] Question 4.1.2-2 
If any new results are available, please provide your inputs on values/pattern of A*B1 and (mean, standard deviation) of B2 for UAV of large size




Framework/values for human 
Summary on company views



E//: To model the scattering off an upright human, linear , where  is an attenuation factor defined in terms of the bistatic angle  as  and  is a modified version of the antenna radiation pattern from TR38.901 defined in decibel scale as follows .
AT&T: For bistatic sensing, to model the RCS of an adult human target with single scattering point
A is mean RCS value given -14.4 dBsm
B2 is modelled using a log-normal distribution with mean 0 dB and standard deviation of 6.7


[Moderator’s note] Better to check if more inputs are available. 

[FL1] Question 4.1.3-1 
If any new results are available, please provide your inputs on values/pattern of A*B1 and (mean, standard deviation) of B2 for human with RCS model 1


[FL3] Proposal 4.1.3-1 
The bistatic RCS of human with RCS model 1 is modelled as
Component A: same as component A of mono-static RCS for human with RCS model 1
Component B1:  where  is the 3D bi-static angle between incident angle and scattered angle
Component B2: same as component B2 of mono-static RCS for human with RCS model 1



[FL1] Question 4.1.3-2 
If any new results are available, please provide your inputs on values/pattern of A*B1 and (mean, standard deviation) of B2 for human with RCS model 2



If any additional comments, please provide it in following table


Framework/values for vehicle with single scattering point
Summary on company views


AT&T:  For bistatic sensing, to model the RCS of a large vehicle with single scattering point
B2 is modelled using a log-normal distribution with standard deviation 6.1


[Moderator’s note] Better to check if more inputs are available. 
[FL1] Question 4.1.4-1 
If any new results are available, please provide your inputs on values/pattern of A*B1 and (mean, standard deviation) of B2 for vehicle with single scattering point


[FL1] Question 4.1.4-2 
If any new results are available, please provide your inputs on values/pattern of A*B1 and (mean, standard deviation) of B2 for vehicle with multiple scattering points



If any additional comments, please provide it in following table


Framework/values for AGV
Summary on company views



[Moderator’s note] Better to check if more inputs are available. 
[FL1] Question 4.1.5 
If any new results are available, please provide your inputs on values/pattern of A*B1 and (mean, standard deviation) of B2 for AGV



If any additional comments, please provide it in following table


[H] Monostatic RCS
Nokia: Table 5  3GPP specified parameters for mid-sized UAV for monostatic scenario

Values for UAV of large size
Summary on company views



[Moderator’s note] Better to check if more inputs are available. 

[FL1] Question 4.2.1 
If any new results are available, please provide your inputs on values/pattern of A*B1 and (mean, standard deviation) of B2 for UAV with large size



If any additional comments, please provide it in following table



[FL3] Proposal 4.2.1-1 
On the monostatic RCS of UAV of large size,
The values/pattern of component A*B1 are generated by the following parameters 

When  is in the range [0°,45° ] or [135°,180°], 
The standard deviation of component B2 is 2.50 dB


Framework/values for human with RCS mode 2
Summary on company views

Angular dependency
Horizontal: IDC, OPPO, LGE
Vertical: IDC, HW, DOCOMO
Not support: BUPT


QC
For model 1, for a child, support a component A which is 5 dBsm lower than the adult:
Component A: -6.37 dBsm
Component B1: 0 dB (already agreed in RAN1#118bis)
Component B2: 


[Moderator’s note] Better to check if more inputs are available. 

[FL1] Proposal 4.2.2-1 
On the monostatic RCS for human with RCS model 2
The monostatic RCS for a scattering point of the target is generated by
The values/pattern A*B1, i.e.,  is deterministic based on incident/scattered angles

Where,


FFS how many rows of the values/pattern A*B1 are defined for the target
Note: each row has a defined applicable range of  and 



[FL1] Proposal 4.2.2-1-rev1 
On the monostatic RCS for human with RCS model 2
The monostatic RCS for a scattering point of the target is generated by
The values/pattern A*B1, i.e.,  is deterministic based on incident/scattered angles

Where,


FFS how many rows of the values/pattern A*B1 are defined for the target
Note: each row has a defined applicable range of  and 
Note: whether the RCS is elevation angle dependent or dependent on both elevation and horizontal angles can be separately discussed


[Moderator’s note] Agreement in Tuesday online
Agreement
On the monostatic RCS for human with RCS model 2
The monostatic RCS for a scattering point of the target is generated by
The values/pattern A*B1, i.e.,  is deterministic based on incident/scattered angles

Where,


FFS how many rows of the values/pattern A*B1 are defined for the target
Note: each row has a defined applicable range of  and 
Note: whether the RCS is elevation angle dependent or dependent on both elevation and horizontal angles can be separately discussed


[FL1] Question 4.2.2-2 
If any new results are available, please provide your inputs on values/pattern of A*B1 and (mean, standard deviation) of B2 for Human with RCS model 2



If any additional comments, please provide it in following table


[FL3] Proposal 4.2.2-2 
On the monostatic RCS of human with RCS model 2,
The values/pattern of component A*B1 are generated by the following parameters 

The standard deviation of component B2 is [?] dB



Values for AGV
Summary on company views


Nokia: Table 7  3GPP specified parameters for quadruped robot for monostatic scenario


[Moderator’s note] Better to check if more inputs are available. 

[FL1] Question 4.2.3 
If any new results are available, please provide your inputs on values/pattern of A*B1 and (mean, standard deviation) of B2 for AGV



If any additional comments, please provide it in following table


[FL3] Proposal 4.2.3-1 
On the monostatic RCS of AGV with single scattering point,
The values/pattern of component A*B1 are generated by the following parameters 

When  is in the range [0°,30° ), 
The standard deviation of component B2 is 2.51 dB

[H] Value of component A for bistatic and monostatic sensing modes

Summary on company views

E//: For mono-static sensing mode, bi-static RCS modelling is needed for indirect paths
E//: For a type of target, mono-static RCS and bi-static RCS constitute the whole RCS to derive value A, B1 and B2. Such A is used to calculate power scaling factor

Component A
different values of component A respectively for monostatic RCS and bistatic RCS of same target
same value of component A for monostatic RCS and bistatic RCS of same target: Nokia, LGE, vivo, BUPT, ZTE, Ericsson, Sony, Tejas


[Moderator’s note] Based on the compromise agreement in last meeting, we need to decide a value for component A for a target. Multiple companies prefer to define same value A for monostatic/bistatic RCS for simplicity
[FL2] Proposal 4.3-1 
The same value of the component A is applied to the monostatic RCS and the bistatic RCS of a target
Exact value of component A is to be discussed per target


Angular correlation of RCS
Summary on company views

Whether to model correlation of RCS of a scattering point in adjacent incident/scattered angles?
Yes (5): Lenovo, LGE, E//, NIST, Sony
Use a correlation distance: Lenovo
Sum of sinusoids: E//
No (11): ZTE, HW, Nokia, vivo, QC, BUPT, CATT, SS(deprioritized), MTK, Xiaomi, Apple(low priority)

Spatial-temporal consistency of RCS : E//, NIST, Lenovo
E//: Model the stochastic B2 with C random scattering centres as 
NIST:  generated by convolving i.i.d. Lognormal random values with the ACF model,  where .
Sony: 


E//: B2 must be continuous over the incidence and scattering angles
E//: Discontinuous behavior leads to non-physical artifacts in the channel, including very high Doppler frequencies and spurious out-of-band artifacts



LGE: RCS as a random time-domain process:
Sony: Consider correlation angle  [º] on B1

NIST: We observe notable correlations across multiple angle lags , indicating that the small-scale RCS (B2) exhibits some spatial (temporal) correlation

Figure 3-7: Small-Scale RCS (B2) autocorrelation function as a function of angle lag.
Sony
Table 1: Summary of RCS simulation results of UAV model option 2 


[Moderator’s note] The existing validation results show that the RCS values fluctuate a lot with the change of incident/scattered angles. However, the RCS value of close/adjacent incident/scattered angles can still have some correlations as discussed in some contributions. On the other hand, some companies comment that the angle dependent pattern of B1 (or A*B1) is already a means to model correlation of adjacent incident/scattered angles. 
[FL1] Question 4.4-1
Companies are encouraged to comment on whether/how to model correlation of RCS of a scattering point in adjacent incident/scattered angles?


[H] XPR to generate polarization matrix
Summary on company views

Xiaomi, Apple, ZTE, BUPT, QC, Sony: The proposed XPR distribution/value are summarized in following table

CMCC: There’s a clear difference between the CPM distributions of monostatic and bistatic modes.
E//: 
Support any orientation of target by defining  in a Local Coordinate System (LCS) and reusing the procedure for the support of arbitrary orientation of BS and UE in section 7.1 of 38.901
CPMsp must be specified in a local coordinate system, in which the z-axis is parallel to the z-axis in the global coordinate system, .
If the change of orientation leads to a change of z axis, such as a vehicle driving on/off a slope, rotation procedure is needed because the cross-polarization matrix is no longer diagonally dominant.

Nokia: Reuse the TR 38.901 log-normal distribution parameters as baseline: 
 for LOS of Umi, and  for LOS of Uma


[Moderator’s note] Based on the agreement from last meeting, one open issue is to collect the values of mean and standard deviation for XPR. Please provide your values if available. 

[FL1] Question 4.5-1 
If any new results are available, please provide your inputs on the mean and standard deviation of XPR to generate the polarization matrix of a direct/indirect path of a scattering point of UAV, human, vehicle, AGV, and other targets 



[FL1] Proposal 4.5-1 
The following mean and standard deviation values of XPR of targets are agreed
UAV: (13.75, 7.07) dB
Human: (19.81, 4.25) dB
Vehicle: (21.12, 6.88) dB


[Moderator’s note] Agreement in Tuesday online 
Agreement
The following mean and standard deviation values of XPR of targets are agreed for monostatic sensing and bistatic sensing as follows:
UAV: (13.75, 7.07) dB
Human: (19.81, 4.25) dB
Vehicle: (21.12, 6.88) dB

Angular correlation of polarization matrix
Summary on company views

Whether to model correlation of polarization matrix (XPR, initial random phase) of a scattering point in adjacent incident/scattered angles?
Yes: Ericsson, CATT (impact to Doppler), IDC
NO: HW, Nokia, LGE, vivo, BUPT, ZTE, QC, Xiaomi

IDC: Initial random phase and XPR of CPM_sp is link-correlated for spatially consistent mobility odelling of the same target only
CATT
The base station rotation procedure for CPM of target is not necessary because the XPR and random phase are generated statistically.


[Moderator’s note] Unlike the discussion on correction of RCS B2, there is no validation result available for XPR. More inputs from companies are necessary. 
[FL1] Question 4.6-1
Companies are encouraged to comment on whether/how to model correlation of XPR/initial random phase of a scattering point in adjacent incident/scattered angles?


RCS for other targets/EO type-1
Summary on company views

E//: For outdoor human scenario, the type of sensing targets which may be evaluated in future study is not limited to pedestrian and can be cyclists, E-Scooter, and motorcyclists.
E//: For the bistatic RCS of birds, use an isotropic model with A between -40 to -20 dBsm for a single bird, and A = 0 dBsm for a migrant flock.

Ericsson: Use the following bistatic RCS model for a single tree: A*B1 with a constant level of 10 dBm2 and a single lobe in the forward direction with A*B1 increasing to 23 dBm2. The B2 standard deviation is approximately 3 dB.

Nokia: Table 6  3GPP specified parameters for robotic arm for monostatic scenario

LGE: Model the monostatic RCS of animal as the product of the angular independent component A = 1.5 dBsm, the component B1=1 and the component B2 having the standard deviation σ = 3.94 dB.

[Moderator’s note] For any other targets, e.g., object creating hazard on road, or certain EO type-1. If the measurement data are available and agreeable, we would try to complete them in the study item. 
[FL1] Question 4.7-1 
Please provide your inputs on values/pattern of A*B1 and (mean, standard deviation) of B2 for human with RCS model 2



If any additional comments, please provide it in following table


Collection on the setup for RCS measurement from companies 

[Moderator’s note] Based the email discussion [Post-120-ISAC-01] and confirmation by Chair, we would create a document to collect details on the setup for RCS measurement/simulation (i.e. vehicle size, frequency, distance, etc). The file include separate sheets for different target types. Please consider adding your information for measurement/odelling. 
/Inbox/drafts/9.7(FS_Sensing_NR)/9.7.2 Channel Modelling/R1-250xxxx Setup on RCS measurement_v000.xlsx


If any additional comments, please provide it in following table


ISAC channel model
ZTE: Dual mobility model in TR 38.901 is used to model the Doppler frequency in background channel of UT mono-static, with the velocity of the reference point setting same as velocity of Tx.
IDC: An unintended target is a blockage factor in the target channel and further study whether Blockage model A or Blockage model B should be implemented
[H] Reference TRs
Summary on company views

Ericsson
It needs evaluation whether BS-aerial UE in 36.777 can be reused for terrestrial UE-UAV link and terrestrial UE-aerial UE channel, especially for indoor Ues.
It needs evaluation whether BS-aerial UE in 36.777 can be reused for aerial UE-UAV link, because it requires changing BS height from at most 35m to up to 300m (aerial UE height).
Both aerial UE and UAV can be of any same or different heights in the large range of [1.5m, 300m]. It needs consideration whether/how LOS probability, pathloss model, shadow fading parameters for different UAV heights in 36.777 can be extended to support combinations of two heights of aerial UE and UAV.
QC
For TRP/UE to aerial UE for FR2, support reusing the channel model of FR1. 
For aerial-UE to aerial-UE, support reusing the D2D channel model from 36.843 A.2.1.2 is used.
IDC
Reuse UMi-AV, UMa-AV and RMa-AV scenarios of TRP to aerial UE channel model defined in TR 36.777 for channel between a normal UE and an aerial UE as a starting point
Capture the same TRs as case 7 for case 9 to model the channel between two aerial Ues as a starting point.
BUPT
For the UAV-UT case, we recommend modifying the BS height to 1.5 m as per TR 38.858, while ensuring that the angular spread values (ASA and ASD for UT) at the UT side align with those in the corresponding UMi, UMa, and RMa scenarios in TR 38.901.
For UAV TR selection in FR2, we propose retaining the LOS probability and path loss calculations from TR 36.777, while adopting Alternative 3 for fast fading odelling (K=15, with all other parameters following TR 38.901).
CATT
TRP-UAV channel defined in TR 36.777 is used to model the channel between UAV and cellular UE.
Channel model between a UE and a RSU and between two UE-type RSUs reuse the V2V channel model with antenna height at RSU changed to 5m, as defined in TR 37.885.
Channel model between a TRP and a RSU should reuse the B2R link modelling in TR 37.885.

[Moderator’s note] We agreed on the reference TRs for the links between TRP-TRP, TRP-UE and normal UE-normal UE. A basic/rough principle for such agreement is to have 38.901-like option. Such a rule can be extended to other kinds of links. In the following Table x for reference TRs, only one option is kept for each pair of link for each scenario. Please check if it is agreeable. 

Table x: Reference TRs
The related sections in the following existing TRs are used as starting point to generate a channel between any two nodes from TRP, normal UE, vehicle UE and aerial UE. 


[FL1] Proposal 5.1-1 
In order to generate Tx-target link, target-Rx link and the background channel, The above table on reference TRs (excluding the already agreed part) is adopted for the mapping between reference TRs and a pair of nodes (STX, SRX, target) 



[FL1] Proposal 5.1-1-rev1 
In order to generate Tx-target link, target-Rx link and the background channel, The above table on reference TRs (excluding the already agreed part) is adopted for the mapping between reference TRs and a pair of nodes (STX, SRX, target) 
FFS RSU type UE


[Moderator’s note] Agreement from Tuesday online
Agreement
In order to generate Tx-target link, target-Rx link and the background channel, the above table on reference TRs (excluding the already agreed part) is adopted for the mapping between reference TRs and a pair of nodes (STX, SRX, target) 
Note: continue discussion for updating the table with RSU type UE
FFS: the generation of background channel based on reference TRs is subject to the addition of low-energy clusters



[Moderator’s note] Let’s check the following proposals on handling RSU type UE

[FL3] Proposal 5.1-2 
In order to generate Tx-target link, target-Rx link and the background channel between a RSU-type UE and another node (TRP, pedestrian UE, vehicle UE, RSU-type UE), the following reference TRs are adopted





[FL3] Question 5.1-3 
For Case 7 “normal UE + aerial UE”, please provide your input regarding how to solve the issue on LOS probability and other FFSs


[H] Parameter values to generated background channel for monostatic

Summary on company views

Nrp = 3: ZTE Corporation, Sanechips, OPPO, BUPT, BJTU, CAICT, Xiaomi, Huawei
Nrp = 1: SS, Apple

ZTE, et al.: Confirm the previous working assumption on background channel for mono-static sensing with the following details:
reference points are dropped for one Tx, based on the Gamma distribution for distance and height of reference point.
The LOS AOD between Tx and the first reference point is generated based on uniform distribution , and the gap of LOS AOD between the Tx and different reference points keeps as .
The background channel is generated based on the channel generated as in existing TR between the real Tx and the reference point in NLOS condition.
The antenna field pattern and array orientation of reference point are set same as Tx. 
Arrival angles for both azimuth and elevation  and  are set equal to departure angles, and coupled with the corresponding departure angles one by one.
The mono-static background channel for the Tx would be sum of channels of the links between the Tx and all related reference points, which is

ZTE et al. 
Proposal 2: For background channel of mono-static sensing, the distance between Tx and the reference point, and the height of the reference point follow parameterized Gamma distribution  with offset , and the related parameters in scenarios of UMa, UMi, RMa, Urban grid, Indoor-office,  and highway are given by:

Huawei: 
Proposal 12: The generation and parameters for the background channel for mono-static sensing can be modelled as:
Step1：deploy the reference points as:




The 3D coordinates of the reference points are:

Step 2: generate the clusters following the TR 38.901 generation steps under NLOS condition with modification as
number of clusters = 8.
SF = 2.5
the absolute delay for each cluster generated as

Step 3: Combine the channels of each BS-RP link.

ZTE, et al. 
Highway: The distribution of reference points of RMa is reused for Highway scenario.
Urban grid: The distribution of reference points of UMa is reused for urban grid scenario.
CATT
For the Mono-static target channel modelling, the determination of delay, angle, K factor and polarization matrix for Tx-target link and target-Rx link should follow the following rules:
Same K factor should be used for two separate links.
LOS AOA and LOS ZOA of target-Rx link should be the same as LOS AOD and LOS ZOD of Tx-target link.
LOS AOD and LOS ZOD of target-Rx link should be the same as LOS AOA and LOS ZOA of Tx-target link.
Delay spread, angle spread and polarization for the two separate links should be generated independently.
The ASA and ZSA of target-Rx link should obey the same statistical distribution characteristics of ASD and ZSD of Tx-target link, respectively.
The ASD and ZSD of target-Rx link should obey the same statistical distribution characteristics of ASA and ZSA of Tx-target link, respectively.
E//: Revert the working assumption from RAN1#120 and continue study Option 2 and Option 3 in the RAN1#118 agreement
Nokia: clutter map is proposed for the background channel


[Moderator’s note] Thanks for all companies working on the parameter values based on the working assumption from last meeting. A joint contribution is available which summarizes data for each sensing scenario. Additionally, a set of values are proposed by Huawei which seems well aligned with the joint tdoc, too. 

[FL1] Proposal 5.2-1
Confirm the previous working assumption on background channel for mono-static sensing with the following details:
 reference points are dropped for one Tx, based on the Gamma distribution for distance and height of reference point.
The LOS AOD between Tx and the first reference point is generated based on uniform distribution , and the gap of LOS AOD between the Tx and different reference points keeps as .
The background channel is generated based on the channel generated as in existing TR between the real Tx and the reference point assuming NLOS condition.
The antenna field pattern and array orientation of reference point are set same as Tx. 
Arrival angles for both azimuth and elevation  and  are set equal to departure angles
The absolute delay model  as agreed for bistatic sensing for the same sensing scenario applies. 
The mono-static background channel for the Tx would be sum of channels of the links between the Tx and all related reference points, which is



[FL1] Proposal 5.2-1-rev1
Confirm the previous working assumption on background channel for mono-static sensing with the following details:
 reference points are dropped for one Tx, based on the Gamma distribution for distance and height of reference point.
The LOS AOD between Tx and the first reference point is generated based on uniform distribution , and the gap of LOS AOD between the Tx and different reference points keeps as .
The background channel is generated based on the channel generated as in existing TR between the real Tx and the reference point assuming NLOS condition.
The antenna field pattern and array orientation of reference point are set same as Tx. 
Arrival angles for both azimuth and elevation  and  are set equal to departure angles
The absolute delay model d3D and  as agreed for bistatic sensing for the same sensing scenario applies. 
The mono-static background channel for the Tx would be sum of channels of the links between the Tx and all related reference points, which is

FFS: Doppler frequency in background channel for monostatic sensing
FFS: whether to add additional very low power clusters
FFS: any update to parameters e.g. angular distribution and delay spread


[Moderator’s note] Further revised based on online discussion and offline 

[FL2] Proposal 5.2-1-rev2
On background channel for mono-static sensing, the following details are provided:
 reference points are dropped for one Tx, based on the Gamma distribution for distance and height of reference point.
The LOS AOD between Tx and the first reference point, which is denoted as AOD1, is generated based on uniform distribution .
The LOS AOD between Tx and the second reference point is AOD1 + 
The LOS AOD between Tx and the third reference point is AOD1 + 
The background channel is generated based on the channel generated as in existing TR between the real Tx and the reference point assuming NLOS condition.
The antenna field pattern and array orientation of reference point are set same as Tx. 
Arrival angles for both azimuth and elevation  and  are set equal to departure angles
The absolute delay model [d3D and]  as agreed for bistatic sensing for the same sensing scenario applies. 
The mono-static background channel for the Tx would be sum of channels of the links between the Tx and all related reference points, which is

FFS: Doppler frequency in background channel for monostatic sensing
FFS: whether/howto add additional very low power clusters
FFS: any update to parameters e.g. angular distribution and delay spread


[Moderator’s note] revised in Wed offline session

[FL3] Proposal 5.2-1-rev3
On background channel for mono-static sensing, the following details are provided:
 reference points are dropped for one Tx, based on the Gamma distribution for distance and height of reference point.
The LOS AOD between Tx and the first reference point, which is denoted as AOD1, is generated based on uniform distribution .
The LOS AOD between Tx and the second reference point is AOD1 + 
The LOS AOD between Tx and the third reference point is AOD1 + 
The background channel is generated based on the channel generated as in existing TR between the real Tx and the reference point assuming NLOS condition.
The antenna field pattern and array orientation of reference point are set same as Tx. 
Arrival angles for both azimuth and elevation  and  are set equal to departure angles
The absolute delay model d3D and  as agreed for bistatic sensing for the same sensing scenario applies. 
Option 1: A scaling factor d_s is applied to d3D. d_s is uniformly distributed with [0, 1] 
Option 2: A scaling factor d_s is applied to d3D. d_s = d3D-c1
The mono-static background channel for the Tx would be sum of channels of the links between the Tx and all related reference points, which is

FFS: Doppler frequency in background channel for monostatic sensing
FFS: whether/howto add additional very low power clusters
FFS: any update to parameters e.g. angular distribution and delay spread
The rays in a stochastic cluster with ZOA at BS less than D degree are dropped [with probability p, p=1] 
D=[90] for RMa, 
D=[60] for UMa



[Moderator’s note] As suggested by the joint contribution, the fitted data for Uma/Rma can be extended to Urban grid and highway. Some further observation from moderator are
For highway, it is derived by Rma for FR1, but is Uma for FR2
For HST, it is derived by Rma
Therefore, the moderator extends/revises the proposal from the joint contribution. Please check if the following proposal is agreeable. 

[FL1] Proposal 5.2-2
The values of the parameters to generated background channel for TRP monostatic sensing for each sensing scenario are provided in the following table 




[FL2 Proposal 5.2-2-rev2
The values of the parameters to generated background channel for TRP monostatic and UE monostatic sensing for each sensing scenario are provided in the following table 
FFS parameter values for other scenarios


[Moderator’s note] Revised in Wed offline session
[FL3] Proposal 5.2-2-rev3 for working assumption
The values of the parameters to generated background channel for TRP monostatic and UE monostatic sensing for each sensing scenario are provided in the following table 
FFS parameter values for other scenarios
An email discussion checking the values after April meeting are preferred, including newly agreed parameters






[Moderator’s note] We already have agreement that large scale parameters are same for the Tx-target and target-Rx links for monostatic sensing. A remaining issue is the small scale parameters as discussed by CATT. For reciprocity, should we assume all small scale parameters are same for the Tx-target and target-Rx links?

[FL1] Proposal 5.2-3
The small scale parameters used to generate the Tx-target link are respectively same as that of the target-Rx link. 



[FL1] Proposal 5.2-3-rev1
The small scale parameters used to generate the Tx-target link are respectively same as that of the target-Rx link for monostatic sensing. 


[Moderator’s note] Agreement after Tuesday online
Agreement
To generate the parameters (in the steps before concatenation), the large-scale parameters and the small-scale parameters used to generate the Tx-target link are respectively the same as that of the target-Rx link for monostatic sensing, where departure angle on one link and arrival angle on the other link are reciprocal.
FFS: whether this applies to initial phase


[H] Polarization matrix normalization
Summary on company views

Whether/how normalization on the polarization of a direct/indirect path, i.e., CPMtx,sp,rx= CPMsp,rx . CPMsp . CPMtx,sp is supported? 
No: LG, Nokia, CAICT
Yes: ZTE, vivo, Samsung, Qualcomm, OPPO, HW, Apple, BUPT
: ZTE
: HW
diagonal-term normalization: QC, Apple
: vivo
: BUPT

Vivo: RAN1 determines whether the power normalization of CPM is necessary after CPM concatenation depends on the value of XPR for CPM of target.
The magnitude of the diagonal elements of each component CPMsp,rx , CPMsp , CPMtx,sp  should be set to 1: Apple

[Moderator’s note] The majority view is to have normalization. ZTE has results comparing different options for normalization and the conclusion is using absolute value is the best. Please check if you are OK with the following proposal. 

[FL1] Proposal 5.3-1 
Normalization on the product of three polarization matrixes of a direct/indirect path, i.e., CPMtx,sp,rx= CPMsp,rx . CPMsp . CPMtx,sp is supported
The scaling factor is 



[FL1] Proposal 5.3-1-rev1 
Normalization on the product of three polarization matrixes of a direct/indirect path, i.e., CPMtx,sp,rx= CPMsp,rx . CPMsp . CPMtx,sp is supported
The scaling factor is 


[Moderator’s note] Agreement in Tuesday online
Agreement
Normalization on the product of three polarization matrixes of a direct/indirect path generated by stochastic cluster, i.e., CPMtx,sp,rx= CPMsp,rx . CPMsp . CPMtx,sp is supported
The scaling factor is 


[H] Power threshold 

Summary on company views

Power threshold for path dropping after concatenation
-40dB: HW, Nokia, CATT, CMCC, OPPO, Xiaomi (-45 first), Apple, Spreadtrum
-25dB: LGE
Inf: QC, IDC

Removing a cluster from background channel referring to the maximum path power in target channel: LGE, Apple
IDC: Do not adopt path dropping after concatenation

Power normalization of target channel after path dropping
Not supported: HW, Xiaomi, Nokia, LGE, CMCC, Panasonic, Apple
Supported: SS, Tiami

Power threshold for cluster dropping for background channel 
The power threshold for cluster dropping in background channel can be discussed together with possible introduction of very low power clusters. 
Option 1: threshold = -25dB, no additional very low power clusters
LG(2nd), CATT, Xiaomi, Apple
Option 2: threshold < -25dB, no additional very low power clusters
HW (-40), Tejas(-Inf)
Option 3: threshold = -25dB, introducing additional very low power clusters
Nokia, ZTE, Lenovo
Option 4: threshold < -25dB, introducing additional very low power clusters
Nokia, ZTE, Lenovo, QC(-Inf)
Option 5: threshold = -25dB, removing a cluster from background channel referring to the maximum path power in target channel 
LG(1st), MTK

Add additional very low power clusters: QC, Lenovo, Tiami
QC, Tiami: Introduce a set of low-power clusters in the background channel which have a power that is in the order of the ISAC target channel’ sensing clusters
Lenovo: clutter with an energy of at least 7 dB [or a required SSNR value corresponding to a sensing task] below the energy of the target channel shall be modelled in the ISAC background/environment channel.
For the generation of the low-energy cluster/rays, [] = [40-240, 1], would be sufficient to obtain required dynamic range of the background channel for the bistatic sensing scenarios.

Huawei: The reference power for removing cluster can follow the TR38.901 without any other updates

Lenovo
For the generation of the low-energy cluster/rays, [] = [180-240, 1], would be sufficient to obtain required dynamic range of the background channel for both bistatic and monostatic sensing scenarios.
The stochastic clutter associated with an ISAC background channel can be odellin via the following steps:

[Moderator’s note] Based on the contributions, -40dB as the power threshold is agreeable

[FL2] Proposal 5.4-1 
Power threshold for path dropping after concatenation is -40dB for target channel


[FL3] Proposal 5.4-1-rev1 
Power threshold for path dropping after concatenation is -25dB for target channel




[Moderator’s note] There is clear common view that power normalization after path dropping is not necessary

[FL1] Proposal 5.4-2 
Power normalization of target channel after path dropping of the target channel is not supported


Agreement
Power normalization of target channel after path dropping of the target channel is not supported.


[Moderator’s note] The most straightforward way is to reuse the threshold -25dB in cluster dropping, which also maintains backward compatibility with communication. However, considering the analysis that the path in background channel may be much higher than a path in the target channel, a simple way to mitigate it is to lower the threshold for cluster dropping in Step 6 generating the background channel. Not dropping a cluster <-25dB will have neglectable impacts to communication (the reason why such cluster is dropped in exiting TR). Therefore, the moderator propose that we reduce the power threshold, e.g. Huawei suggests to use -40dB. 

[FL2] Proposal 5.4-3 
To generate the background channel, the power threshold for removing clusters in step 6 in section 7.5, TR 38.901 is -40 dB 


[FL3] Proposal 5.4-3 
To generate the background channel, the power threshold for removing clusters in step 6 in section 7.5, TR 38.901 is reused


[Moderator’s note] Regarding the FFS point of additional very low power clusters, please proponent company provide your solution. It is good if the proponent can converge to a single option, otherwise it is hard to move forward. 

[FL1] Question 5.4-4 
Whether/how to model some lower power NLOS clusters in background channel beyond those generated by existing section 7.5, TR 38.901?



[FL2] Proposal 5.4-4 
The ISAC background channel can be generated between a sensing Tx and a sensing Rx or RP (relevant for monostatic case) via the following steps:
Step 1: generate a first set of clusters/rays according to TR 38.901
Step 2: generate a second set of NLOS clusters/rays according to TR 38.901, where the power of the second set of clusters/rays should be scaled down such that


(,   are the power of the n-th cluster from the first and second set, respectively).
FFS any modification from 38.901 for the second set including the number of clusters N, and the number of rays within each cluster M, value of G, the large scale statistics (for generation of the second set of clusters)
Example 0. G = -25dB
Example 1 N=360, M=1, G=0dB, with uniform delay and angle (for mono-static case)
Example 2 N=120, M=1, G = -25dB, no further change from 38.901
Note: the step 2 is an additional modeling component


[Moderator’s note] Revised in Wed offline session. Adding 36.777, 38.858
[FL3] Proposal 5.4-4-rev1 
The ISAC background channel can be generated between a sensing Tx and a sensing Rx or RP (relevant for monostatic case) via the following steps:
Step 1: generate a first set of clusters/rays according to TR 38.901(or other related TRs)
Step 2: generate a second set of NLOS clusters/rays according to TR 38.901 (or other related TRs), where the power of the second set of clusters/rays should be scaled down such that


(,   are the power of the n-th cluster from the first and second set, respectively).
Where, N is the number of clusters, M is the number of rays within each cluster, value of G relates to power
Option 1: N=360, M=1, G=0dB, with uniform delay and angle (only for mono-static case)
Supported by: Nokia
Option 2: N=60, M=1, G = -25dB, no further change from 38.901, 36.777, 38.858 (i.e., utilizing the same DS, ASA, ASD, ZSA, ZSD, ,  as used for the first step)
Supported by: Xiaomi, ZTE, Lenovo, MTK, Qc, CMCC, IDCC, 
Note: the step 2 is an additional modeling component


[H] Impact of height of target on LOS probability or pathloss
Summary on company views

Breaking point distance
HW: When the path loss model of Umi, Uma and Rma scenario of TR38.901 is used for the target channel, only the  is applied in the target channel irrespective of the breakpoint distance.

[Moderator’s note] In general, the scattering point location for the target (human, vehicle, …) may be lower than the commonly used UT height, e.g., 1.5m. It mainly impacts LOS probability determination and pathloss calculation. A simple solution is to extend the application range of the formulas in the current TR. However, as discussed by several companies, some issues are found, hence some solutions are proposed. 

[FL3] Proposal 5.5-1 
For sensing scenario UMi, UMa, RMa, UMi-AV, UMa-AV and RMa-AV, the height of target is used to calculate the LOS probability and pathloss, regardless of the lower bound in the existing TRs that are referred to generate ISAC channel. 



[Moderator’s note] The possible issues caused by extending application range of hUT includes 1) low/negative distance of breaking point for Umi/Uma/Rma; 2) reduced LOS probability. Please provide your views on the favorite option. 

[FL1] Question 5.5-2 
Please provide your views/solutions on the following issues
Issue 1: Negative dBP result in using the large pathloss  when hUT is reduced to be less than 1m
Issue 2: LOS probability is reduced a lot for InF scenario when hUT is reduced


[FL3] Proposal 5.5-2 
In sensing scenario UMi, UMa, RMa, UMi-AV, UMa-AV and RMa-AV, the minimum d_BP is 10m. 



Power normalization between target channel and background channel

Summary on company views

Alt 1: Power normalization on both target channel and background channel
Lenovo, Apple, Nokia, CATT, LGE, OPPO, QC, CT, Spreadtrum
Alt 2: Only the power of the background channel is scaled down to make total power normalized
EURECOM, ZTE, IDC, OPPO
Alt 3: the target channel of a target will replace one cluster in the background channel
BUPT (indoor/outdoor scenarios), Panasonic

OPPO: The power normalization in combining the target channel(s) and background channel is formulated as a linear programming problem, solved as following. 
The power normalization coefficient for the background channel is 
The power normalization coefficient for a target channel is 
QC: Support the following power normalization between the target and the background channel:
, where  is such that 
BUPT: When combining the target and background channels, different options can be selected based on the scenario category or blockage situation:
Method 1: In UAV scenarios, directly superimpose the target and background channels (Option 1). In indoor/outdoor scenarios, remove background cluster c that are closest to the target in the angular domain and replace them with the target channel (Option 2-Alt 3). 
Method 2：Remove background clusters that are blocked by the target in the angular domain. The possibility of blockage is high in indoor and outdoor scenarios (Option 2-Alt 3) but relatively low in UAV scenarios (Option 1).

Whether/how to specify a condition to select Option 1 or 2
Yes: BUPT
No: CATT

[Moderator’s note] Given Option 2 for power normalization is already agreed in an earlier agreement, the moderator would like to check whether we could follow the majority view among the 3 alternatives on this issue. 
[FL1] Proposal 5.7-1 
Option 2-Alt 1, i.e., power normalization applied on both target channel and background channel, i.e.,  is adopted to normalize the power of ISAC channel, where  is such that  



[Moderator’s note] Regarding ‘FFS condition to select option, e.g. depending on scenario, sensing mode, number of target/EO type-2’, please provide your view on anything should be specified or not. 
[FL1] Question 5.7-2 
Companies are encouraged to provide views on whether/how to specify a condition to select Option 1 ‘no power normalization’ and Option 2 ‘with power normalization’ in the combination of target channel and background channel. 


Doppler of moving scatters

Summary on company views

Reuse 7.6.10: HW, LGE

OPPO: Maximum speed and ratio of moving scatters depends on scenarios. 
Speed of 95%-100% moving scatters follows uniform distribution between 0 and 180km/h for UAV case 
Speed of 95%-100% moving scatters is 0 for indoor case 
Speed of 50% moving scatters is 3-60km/h and speed of remaining moving scatters is 0 for UMa/UMi.
Samsung: Clarify the scope of mobility of stochastic clutters
SS: due to environmental effects such as wind-induced mobility or if there are other factors related to target channel modeling, such as target mobility.
E//
Option 1: Use the existing procedure in clause 7.6.10 in TR 38.901, which creates Doppler variations for a proportion p of the stochastic clusters in the background channel
require many new measurement campaigns
Option 2: Drop additional moving unintended targets and use the target channel model for each of these
Apple
FFS1: the maximum speed of moving scatterers should not exceed maximum speed of target, Tx or Rx
FFS2: the ratio of moving scatterers among all scatterers depends on evaluation goal.
BUPT
The Micro-Doppler may need to be considered in ISAC channel modelling, and the formula   can be used as a starting point for the modelling of the Micro-Doppler.

[Moderator’s note] Inputs on how to handle maximum speed and ratio for moving scatters are appreciated. 
[FL1] Question 5.8-1 
Companies are encouraged to provide inputs on the following FFS points. 
FFS: maximum speed of moving scatterers
FFS: ratio of moving scatterers among all scatterers


Micro-Doppler
Summary on company views

Specify function for micro-Doppler
Neutral: HW
Yes: Nokia, QC, OPPO, vivo
NO: LGE, EURECOM

UAV: QC, OPPO, IDC
Human: QC,vivo, OPPO, BUPT,IDC
Bird: OPPO

Panasonic: Discuss whether the micro-Doppler patterns are per target or per scattering point
E//: Since micro-Doppler is essential for distinguishing wanted and unwanted targets, methods to model micro-Doppler are needed for the completion of the Study Item.
OPPO:

Vivo
	Eq. 8
	Eq. 9

IDC
Table 2: Micro-Doppler functions for micro-motions of humans and UAVs.

Nokia: the micro-Doppler modeling shall be based on the dual mobility modeling of Section 7.6.10 of TR38.901 as baseline

[Moderator’s note] The following proposal should be agreeable. 
[FL1] Proposal 5.9-1
Micro-Doppler, if enabled, is generated per scattering point for a target.


[Moderator’s note] RAN1 already agreed on the placeholder for micro-Doppler. If there is remaining TU, it is nice to decide certain detailed functions to handle micro-Doppler
[FL1] Question 5.9-2
Companies are encouraged to input on the proper functions/models for micro-Doppler



Absolute delay


Summary on company views

Confirm the WA: Apple, ZTE
QC: Support the absolute time of arrival modelling for the highway and urban grid scenarios. At least for the urban grid scenario use the same parameter values as that from the UMi scenario for the TRP to UE links.
FFS: The parameter values for the highway scenario.
OPPO: Before RAN1 confirms the RAN1 #120 working assumption on absolute delay, RAN1 seeks for an agreement on a LOS scattering model with non-zero Δτ being applied, in order to retain a odelling feature that has already been agreed.

[Moderator’s note] From last meeting, the application of absolute delay in ISAC channel model is agreeable. The concern at that time is the parameter values for  may not be available. As discussed by OPPO, if the WA is confirmed, it means there is no case that absolute delay is not enabled. Consequently, the procedure in the early agreement will not happen. 

[FL2] Proposal 5.10-1 
The following working assumption is confirmed


Agreement
The following working assumption is confirmed

[Moderator’s note] Following the discussion from QC, an observation is that the channel model for urban grid, highway and HST are derived based on Uma and/or Rma. Therefore, the moderator makes the following proposal. 

[FL2] Proposal 5.10-2 
To generate the absolute delay model for sensing scenarios Urban grid, highway and HST
For Urban grid, the values of parameters for  of scenarios UMa are reused. 
For Highway, the values of parameters for  of scenarios RMa and UMa are reused for FR1 and FR2 respectively. 
For HST, the values of parameters for  of scenarios RMa are reused. 


[FL3] Proposal 5.10-2-rev1 
To generate the absolute delay model for sensing scenarios Urban grid, highway and HST
For Urban grid, the values of parameters for  of scenarios UMa are reused. 
For Highway, the values of parameters for  of scenarios RMa and UMa are reused for FR1 and FR2 respectively. 
For HST, the values of parameters for  of scenarios RMa and UMa are reused for FR1 and FR2 respectively. 


EO type-2 
Huawei
When sensing target is modelled with multiple scattering points, 
The EO ray is generated per scattering point, i.e. Tx-EO-STsp-Rx, Tx-STsp-EO-Rx.
For concatenation with EO rays, the EO ray is concatenated with other rays as if it is a LOS ray.

Model arbitrary orientations of type 2 EOs: E//

E//: specular reflection is modelled, if Type-2 EO is of the same size as or larger than the first Fresnel zone. Otherwise, it is not modelled
The radius of the first Fresnel zone is approximately given by:

for tx—target distance d₁ and target—rx distance d₂, and wavelength λ.

EO type-2 in background channel
Summary on company views

EO type-2 in background channel if it is modelled in target channel
Yes: Huawei, Sony, ZTE, LGE, Lenovo, EURECOM, Spreadtrum
NO: Ericsson, DOCOMO, Nokia, CMCC, BUPT, QC, CATT, CICTCI, IDC
Neutral: Xiaomi

E//: 
Since stochastic clusters have been used to generate multipath propagation in UE-BS communication channel, the need for a deterministic Type-2 EO in the background channel is not clear.
the received power of the sensing Rx’s in the ISAC model with the absence of sensing targets would be different from that in the legacy UE-BS communication channel.

[Moderator’s note] A larger number of companies perfer to not model EO type-2 in background channel, but there is still quite a few companies prefer to have it. Therefore, the moderator would like to try a proposal in the middle, say the configuration of EO type-2 can be controlled separately for target channel and background channel. 
[FL3] Proposal 6.1-1 
EO type-2 is modeled in background channel as optional feature
Whether to model EO type-2 in target channel and background channel can be configured separately. 


[H] LOS condition considering EO type-2
Summary on company views

Option A: HW, Nokia, QC, BUPT, Panasonic, LGE, Samsung, HW, Nokia, ZTE, EURECOM, LGE, Xiaomi, Apple, Spreadtrum, CT, Sony, MTK, NVIDIA
The LOS probability equation defined in TR38.901: HW, Panasonic, Sony, EURECOM
Opiton B: Lenovo, CATT, IDC, DOCOMO, Ericsson, IDC, CATT, SK Telecom, Tejas
Type-2 EO has no impact on LOS/NLOS condition

Option A: HW, Nokia, QC, Panasonic, LGE, HW, Nokia, ZTE, EURECOM, LGE, [SS], Xiaomi, Apple, Spreadtrum, CT, Sony, MTK, NVIDIA
The LOS probability equation defined in TR38.901: HW, Panasonic, Sony, EURECOM
Opiton B: Lenovo, CATT, IDC, DOCOMO, Ericsson, IDC, CATT, Tejas
Type-2 EO has no impact on LOS/NLOS condition

HW: The EO type2 as a large and stationary building should not be defined as a blocker according to the blockage model in TR38.901.
E//: The legacy soft LOS state is applicable to ISAC channel model
E//: 
Option B is in line with existing procedure for blocking in TR 38.901, where the blocking does not change the LOS state.
With Option A, the spatial consistency between BS-target link and BS-UE channel is broken, when the target and UE are close to each other
Option A may cause a hard transition in the channel response as the targets moves, similar to UT movement, which legacy communication channel tries to avoid
Option A is more suitable for the map-based hybrid channel model or ray-tracing than the stochastic channel stated in section 7.5 of 38.901

[Moderator’s note] To make a complete proposal, Option A is revised based on the comments from proponent companies.  Please each company provide your preferred option. Down selection should be done in RAN1 #120bis.
[FL3] Proposal 6.2-1 
Down-select in RAN1#120bis one option from the following two options to determine the LOS condition of the Tx-target link and target-Rx link?
Option A: If type-2 EO is in the LOS ray of one link, the link is determined as NLOS condition, and otherwise use the LOS probability equation defined in existing TRs to determine the LOS/NLOS condition
FFS changes to the LOS probability defined in existing TRs
FFS details on blockage by EO type-2
Option B: Use the LOS probability equation to determine the LOS/NLOS condition of one link, and then the impacts of type-2 EO is modeled by a blockage model
Note: If EO type-2 is agreed to be modelled in background channel, the agreed option is extended to LOS conditioin determination for background channel. 


[H] EO type-2 for a link in NLOS condition
Summary on company views

ZTE: The pathloss of NLOS ray due to EO type 2 in the STX-SPST link or SPST-SRX link is calculated by , where  is the total propagation distance due to EO type2.
CATT: If EO type-2 is modelled when NLOS condition is determined for Tx-Target link or Target-Rx link:
The pathloss of Tx-Target link or Target-Rx link in NLOS condition with EO type-2 is calculated based on the LOS condition pathloss model
The channel impulse response equation of Tx-Target link or Target-Rx link in NLOS condition with EO type-2 should be modified as following:


[Moderator’s note] The existing behavior in 7.6.8, TR 38.901 assume the LOS ray is present, then power of ground reflection ray is calculated. The same principle is inherited for EO type-2 in LOS condition. As commented by some companies that EO type-2 is valuable for NLOS condition, the solution to calculate the path power is missing

[FL2] Question 6.3-1 
Please provide views on whether/how to model specular reflected ray of EO type-2 in a link with NLOS condition. 


[FL3] Proposal 6.3-1 
In NLOS condition, the pathloss of the ray specular reflected by an EO type 2 in the STX-SPST link or SPST-SRX link is calculated by , where 
 is a pathloss assuming a LOS condition for the STX-SPST link or SPST-SRX link
 is the total propagation distance due to EO type-2



Whether/how to normalize the power of target channel, background channel or the combined channel if EO type-2 is modeled?
Summary on company views

NO: Nokia, LG, vivo, CATT
Open: ZTE

[Moderator’s note] The existing behavior in 7.6.8 is to add the ground reflection ray without further power normalization. The number of EO type-2 may be large in a scenario, but number of strong EO type-2 that can be modeled for a link is always limited. Therefore, we may follow the existing behavior in 7.6.8, TR 38.901
[FL1] Proposal 6.4-1 
Additional power normalization is not considered due to the presence of EO type-2 
Note: this is aligned with the behaviour handling the power of a NLOS ray specular reflected by the ground in section 7.6.8, TS 38.901


Spatial consistency 
CATT: The existing spatial consistency model in TR 38.901 (i.e., site-specific correlation) is reused to model correlation of links between one RSU and different STs/UEs, instead of using the newly defined link correlation.
[H] General question
Is there correlation between the multiple points of a target if spatial consistency is NOT enabled?
Yes: Huawei?
HW: In Step 2 (i.e., the basic procedure), LOS/NLOS condition of the SPs within the same ST are correlated
No: vivo?

CATT
By default, initial random phase of target CPM remains unchanged even if target position changes during simulation. If spatial consistency is considered, initial random phase of target CPM may be further added in the correlation parameter list.

Concatenation Option 3 (1-by-1 random mapping of Tx-target and Tx-Rx link)
If concatenation Option 3 is used, should we update the set of generated paths during the movement of Tx, target and/or Rx?
NO: HW, Nokia, CATT, ZTE

Path dropping after concatenation of Tx-target and target-Rx link
Should we update the set of remaining paths after path dropping after concatenation during the movement of Tx, target and/or Rx?
NO: HW, CATT, ZTE

[Moderator’s note] Reading the contributions, it seems different companies have different understanding on default behavior when spatial consistency is not enabled. Let’s try to clarify it. 

[FL1] Question 7.1-1
When spatial consistency is NOT enabled, what are the understandings on the following questions?
Can we assume the Tx/target/Rx position is unchanged in a simulation drop?
Note: when position is unchanged, Tx/target/Rx velocity of Tx/target/Rx can still be modelled in the simulation, e.g., for Doppler
If changing the Tx/target/Rx position is supported, can we assume the large/small scale parameters of Tx-target link, target-Rx link and the background channel are regenerated independently?
If changing the Tx/target/Rx position is supported, can we assume the RCS component B2 and XPR/initial random phase of the target are regenerated independently?


[FL2] Proposal 7.1-1
When spatial consistency is NOT enabled, the Tx/target/Rx position is unchanged in a simulation drop



[Moderator’s note] When spatial consistency is enabled, the set of paths generated by concatenation Option 3 should not be updated during movement of Tx, target and/or Rx. Otherwise, the spatial consistency is broken. 

[FL1] Proposal 7.1-2 
When spatial consistency is enabled, the set of paths generated by concatenation Option 3 (1-by-1 random mapping) is not updated during movement of Tx, target and/or Rx. 



[FL2] Proposal 7.1-2-rev1 
When spatial consistency is enabled, the 1-by-1 random coupling generated by concatenation Option 3 is not updated during movement of Tx, target and/or Rx, if the LOS condition of the Tx-target and target-Rx links are not changed.


Agreement
When spatial consistency is enabled, the 1-by-1 random coupling generated by concatenation Option 3 is not updated per simulation drop even if Tx, target, Rx positions change during simulation.


[Moderator’s note] When spatial consistency is enabled, the set of remaining paths after path dropping after concatenation of Tx-target and target-Rx link should not be updated during movement of Tx, target and/or Rx. Otherwise, the spatial consistency is broken. 
[FL2] Proposal 7.1-3 
When spatial consistency is enabled, the set of remaining paths after path dropping after concatenation of Tx-target and target-Rx link is not updated during movement of Tx, target and/or Rx. 


[FL3] Proposal 7.1-3-rev1 
When spatial consistency is enabled, the set of remaining paths after path dropping after concatenation of Tx-target and target-Rx link is not updated per simulation drop even if Tx, target, Rx positions change during simulation.


[H] Cases that spatial consistency are supported or not supported
Summary on company views



Whether to consider spatial consistency for the links that are generated referring to channel models with parameter values of different scenarios
E.g., between TRP-target/UT link in one scenario and target/UT-UT link in another scenario
Not modeled: HW, Nokia, LGE, vivo

Whether to consider spatial consistency for TRP-target/UT link and target/UT-UT link, if both links are referring to same scenario though the height of TRP and UE are different, e.g., UMi, InH, InF
Not modeled: HW, Nokia, BUPT
BUPT
f the height difference between the TRP and the UT/target is significant—as in UMi, UMa, RMa, Highway, and Urban grid scenarios—the statistical characteristics of the transmitter and receiver sides exhibit notable differences
if the target-UT link follows 38.858, the condition “ASD and ZSD statistics updated to be the same as ASA and ZSA for UE-UE” applies.
Support: LGE, vivo

[Moderator’s note] Based on the discussion in last meeting, it should be quite agreeable if the two links are generated using different parameter value sets of channel model. For background channel for TRP monostatic sensing, it is straightforward there is no spatial consistency for the virtual receivers/reference points of different TRPs 
[FL3] Proposal 7.2-1
Spatial consistency is not modelled for
the links that are generated referring to channel models with parameter values of different communication scenarios
E.g., between TRP-target/UT link in one scenario and target/UT-UT link in another scenario
the background channels for TRP monostatic sensing of different TRPs



[Moderator’s note] For sensing scenario UMi, InH and InF, it is likely we use the channel model referring the same communication scenario to generate TRP-UT/ST link and UT-ST/UT link. However, as discussed by BUPT, the ASD/ZSD may still be different for the two links. Therefore, it is proposed to not model spatial consistency for the links. 
[FL3] Proposal 7.2-2
Spatial consistency is not modelled between TRP-target/UT link and target/UT-UT link for sensing scenario UMi, InH and InF



[Moderator’s note] Then, it is a question, whether/how to model spatial consistency for the virtual receivers/reference points for UE monostatic sensing of different UEs or the same UE (mobility)?
[FL3] Question 7.2-3
Whether/how the spatial consistency for the background channels for UE monostatic sensing of different UEs or the same UE (mobility) can be supported? 
Please proponent company provide values of all necessary parameters for the model, e.g., the correlation distance, etc. 


Additional parameters to be considered for spatial consistency 

Summary on company views

Any additional parameters?
New parameter for Gamma distribution of background channel for monostatic sensing: ZTE
Note: this discussion is included in 7.1-3. Let’s start from checking whether it can be modelled and what is the solution and the required parameter values
No more: HW, Nokia, LGE, vivo

[Moderator’s note] As captured in the note of the agreement, RAN1 still need to check whether certain new parameters can be considered for the new spatial consistency model. In fact, this question is also applicable to the existing spatial consistency model which is reused for TRP-UE/ST links. Therefore, the moderator makes the following general question. 
[FL1] Question 7.3-1
Which new parameters should be considered for spatial consistency?


[H] Spatial consistency between multiple scattering points
Summary on company views

Huawei: Spatial consistency among multiple scattering points of the same target could be treated as different links.
BUPT
For targets such as small UAVs, large UAVs (in RMa and UMa scenarios), and humans, where the large-scale parameters between multiple points are highly correlated, it is recommended to reuse the spatial consistency results of a single point.
For targets such as vehicle Type 1, vehicle Type 3, and large UAVs (in UMi scenarios), it is recommended to model the spatial consistency for multiple points separately.
BUPT
We suggest calculating the fixed spatial decay coefficients between target multiple points beforehand. Once spatial consistency for any single point is calculated, apply these coefficients to efficiently and accurately model ISAC multi-point spatial consistency.

The multiple scattering points of a target are handled as if multiple targets with single scattering points
Yes: vivo, LGE


Should the correlation between multiple scattering points modelled by a spatial consistency procedure or other solution?

[FL3] Proposal 7.4-1
When spatial consistency is NOT enabled, channels of the multiple scattering points of a target are uncorrelated
Spatial consistency, if enabled, for the links between BS/UT and multiple scattering points of a target are modelled as if multiple targets with single scattering point. 



Solutions for new spatial consistency
Summary on company views

Any preference or more options?
Option 1: global grid (aka. Unified grid) + shifting UT/ST locations
ZTE, CATT, IDC
Option 2: direct modelling on the correlation of grids of different UT/ST, e.g., Cholesky decomposition
Vivo, LGE, SPRD
Option 3: direct modelling on the correlation of grids of different UT, e.g., Cholesky decomposition
Option 4: direct modelling on the correlation of grids of different ST, e.g., Cholesky decomposition

Vivo: The complexity reduction of target-specific method can be considered, e.g., by reducing the size of grid and using the combination of interpolation and extrapolation


[Moderator’s note] It is also important for us to try to align the understanding on exact solution to model spatial consistency for ST/UT links. 

Note: Intention is NOT to discuss the solution(s) for new spatial consistency ‘link-Correlated’ using offline/online session. 
[FL1] Proposal 7.5-1
Please provide details on the preferred solutions to the new spatial consistency model of ‘link-correlated’


[H] 3D spatial consistency
Summary on company views

3D spatial consistency
the existing 2D correlation distance in Table 7.6.3.1-2 in TR39.901 is extended to 3D correlation distance: vivo HW, Xiaomi, EURECOM, Nokia, LGE, CATT, ZTE, CMCC

Vivo: Model correction of target specific 3D grid by Cholesky decomposition of correlation matrix
E//: If spatial consistency in vertical plane is not supported by ISAC channel model, vertical mobility is not supported for UAV sensing

[Moderator’s note] Companies are encouraged to check if the following proposal is agreeable. 

[FL1] Proposal 7.6-1 
The existing 2D correlation distance in Table 7.6.3.1-2 in TR39.901 is reused as 3D correlation distance for ISAC channel at least for UAV scenario


[FL2] Proposal 7.6-1-rev1 
The existing horizontal correlation distance in Table 7.6.3.1-2 in TR38.901 is reused as vertical correlation distance for ISAC channel at least for UAV scenario



[FL3] Proposal 7.6-1-rev2 
The existing 2D correlation distance in Table 7.6.3.1-2 in TR39.901 is reused as 3D correlation distance for ISAC channel at least for UAV scenario


Procedure A vs. B for spatial consistency
Summary on company views

Can we concluded both spatial consistency procedures A and B in 7.6.3.2 in TR 38.901 are reused to support spatial consistency of ISAC channel STX/SRX/ST is/are moving?
Both: HW, Nokia, LGE, vivo, CATT, ZTE, CMCC (B is better). Tejas
A: Nokia, SPRD

[Moderator’s note] There is limited discussions from the contributions. However, since procedure A/B are supported in the existing 38.901, it may be supported by default, subjected to RAN1 discussions. Companies are encouraged to comment on the following proposal. 
[FL1] Proposal 7.7-1
Both spatial consistency procedures A and B in 7.6.3.2 in TR 38.901 are reused to support spatial consistency of ISAC channel STX/SRX/ST is/are moving

Link level channel model
Summary on company views

Option 1: Based on existing CDL channel model, 
Alt 1: add one or more clusters representing target(s): HW (parameters up to evaluation assumptions. A range can be defined), vivo, CATT, ZTE, BUPT

Alt 2: Update the parameters of one or more cluster to represent target(s)

Option 2: Reducing the system level channel model for ISAC to single Tx and single Rx: MTK

Parameter values for the target cluster to be decided in evaluation stage: Huawei
certain modification, e.g., the delay, angle, velocity or doppler parameter to the target cluster: vivo

Ericsson: For link-level ISAC channel models,
H_ISAC=H_target+H_background still holds.
legacy CDL models are reused to model Tx-target and target-Rx links of target channel and Tx-Rx channel of background channel.
target channel is generated by concatenating Tx-target and target-Rx link


[Moderator’s note] Companies are encouraged to comment on the following proposal. 

[FL1] Question 8.1-1  
Which option is preferred to model link-level channel for ISAC? 
Option 1: Based on existing CDL channel model, 
Alt 1: add one or more clusters representing target(s)
Alt 2: Update the parameters of one or more cluster to represent target(s)
Option 2: Reducing the system level channel model for ISAC to single Tx and single Rx
Option 3: The Tx-target link and target-Rx link are modelled by separate CDL channels, concatenation is then performed to get the target channel; the background channel is modelled by another CDL channel. 
Option 4: Not supported



[FL3] Proposal 8.1-1  
The link-level channel for ISAC is generated by adding add one or more clusters representing target(s) to the existing CDL channel model
Values of parameters of the added cluster(s) can be discussed in performance evaluation stage


[FL3] Proposal 8.1-1-rev1  
The link-level channel for ISAC is generated by adding add one or more clusters representing target(s) to the existing CDL channel model
Values of parameters of the added cluster(s) can be discussed in performance evaluation stage
TDL channel model from exiting 38.901 is not enhanced for ISAC channel model
Hybrid channel model
Summary on company views

ZTE: The procedure of hybrid channel modelling with RT simulation in TR 38.901 can be reused and enhanced for sensing. Specify the following typical maps and characteristics of sensing targets to align the simulation assumptions:
Urban grid map defined in 3GPP TR 37.885 
The well-known Manhattan map from open source
Indoor map defined in IEEE 802.11 WLAN
EM parameters defined for radar material by ITU 

[Moderator’s note] ZTE provides the modifications to incorporate ISAC channel model into the map-based hybrid channel model in existing TR 38.901. Companies are encouraged to comment on defining ISAC channel based on map-based hybrid channel model. 
[FL1] Question 9.1-1  
Please provide your view whether/how ISAC channel based on map-based hybrid channel model should be supported I Rel-19. If so, how to achieve it? 

3GPP TSG RAN WG1 #120bis			 R1-2502556
Wuhan, China, April 7th – 11th, 2025
Agenda item:	9.7.2
Source:	Moderator (Xiaomi)
Title:	Summary #4 on ISAC channel modelling
Document for:	Discussion/Decision

Proposal
The bistatic RCS of UAV with small size is modelled as
Component A: same as component A of mono-static RCS for UAV of small size
Component B1:  where  is the 3D bi-static angle between incident and scatter angle
Component B2: same as component B2 of mono-static RCS for UAV of small size


Proposed conclusion
No peak of bistatic RCS values is observed in the specular reflection direction for human.

[FL1] Proposal 7.6-1 
The existing 2D correlation distance in Table 7.6.3.1-2 in TR38.901 is reused as 3D correlation distance for ISAC channel at least for UAV scenario

[FL1] Proposal 7.1-2 
When spatial consistency is enabled, the set of paths generated by concatenation Option 3 (1-by-1 random mapping) is not updated during movement of Tx, target and/or Rx. 
Note: the values of delay, angle and power could be changed based on spatial consistency.


[FL1] Proposal 7.1-2 
When spatial consistency is enabled, the 1-by-1 random coupling generated by concatenation Option 3 is not updated during movement of Tx, target and/or Rx.


Wednesday (Apr. 9)

After Wednesday online 

Agreement
When spatial consistency is enabled, the 1-by-1 random coupling generated by concatenation Option 3 is not updated per simulation drop even if Tx, target, Rx positions change during simulation.


[FL2] Proposal 7.6-1-rev1 
The existing horizontal correlation distance in Table 7.6.3.1-2 in TR38.901 is reused as vertical correlation distance for ISAC channel at least for UAV scenario.


[FL2] Proposal 4.1.1-2-rev2
For vehicle with single/multiple scattering points, down select one option  generating bistatic RCS. 

Option C:
Define the following two functions


The values/pattern A*B1, denoted as  of the bistatic RCS for a SPST is determined by
A first peak of bi-static RCS centred in the back-scattering direction of the incident direction is calculated as

A second peak of bi-static RCS centred in the specular reflection direction of the incident angle is calculated as

, (it is a concave function) 
For the front of vehicle, k1 = 15, k2 = 1.65
For the back of vehicle, k1 = 17.5, k2 = 1.65
For the left or right of vehicle, k1 = 14.5, k2 = 1.55
For the roof of vehicle, FFS
 is within 0~180 degrees.  is the absolute angle between the incident angle and scattering angle within the plane of incident direction () and scattering direction ().
 is the specular reflection direction, 
The final bistatic RCS value for incident/scattered angles () is 
The effect of forward scattering  is -Inf in Rel-19
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs

Option D:
The values/pattern of A*B1 of bistatic RCS is given by:

	where


 is applied to the  within 0~180 degrees. k1= 6 and k2=1.  is the absolute angle between the incident and scattering within the plane of incident direction () and scattering direction ().
The angles of () are the projections of the bisector angle on the vertical plane and the horizontal plane, respectively.
FFS: bisector angle when  is 180 degrees
The effect of forward scattering  is -Inf in Rel-19
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs
FFS: how to avoid angular discontinuity


Agreement
The following working assumption is confirmed


Thursday (Apr. 10)

After Thursday online session

Working assumption
For vehicle with single/multiple scattering points, the bistatic RCS is generated by
Option D:
The values/pattern of A*B1 of bistatic RCS is given by:

	where


 is applied to the  within 0~180 degrees. k1= 6 and k2=[1 or 1.65].  is the absolute bistatic angle between the incident ray and scattering ray within the plane of incident direction () and scattering direction ().
The angles of () are the projections of the bisector angle on the vertical plane and the horizontal plane, respectively.
FFS: RCS value when  is 180 degrees
The effect of forward scattering  is -Inf in Rel-19
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs
FFS: how to avoid angular discontinuity
Continue study on a new formula for  to resolve the issue of angular discontinuity. 
The new formula should retain following property: the linear bistatic RCS for a vehicle with single scattering point is the sum of the bistatic RCS of the multiple scattering points of the vehicle
the following formula can be a reference for the study 

 


[FL3] Proposal 5.2-1-rev3
On background channel for mono-static sensing, the following details are provided:
 reference points are dropped for one Tx, based on the Gamma distribution for distance and height of reference point.
The LOS AOD between Tx and the first reference point, which is denoted as AOD1, is generated based on uniform distribution .
The LOS AOD between Tx and the second reference point is AOD1 + 
The LOS AOD between Tx and the third reference point is AOD1 + 
The background channel is generated based on the channel generated as in existing TR between the real Tx and the reference point assuming NLOS condition.
The antenna field pattern and array orientation of reference point are set same as Tx. 
Arrival angles for both azimuth and elevation  and  are set equal to departure angles
The absolute delay model d3D and  as agreed for bistatic sensing for the same sensing scenario applies. 
Option 0: no scaling factor is applied to d3D
Option 1: A scaling factor d_s is applied to d3D. d_s is uniformly distributed with [0, 1] 
Option 2: A scaling factor d_s is applied to d3D. d_s = d3D-c1
Option 3: A scaling factor d_s is applied to d3D. d_s is within range [0, 1]. FFS value of d_s 
The mono-static background channel for the Tx would be sum of channels of the links between the Tx and all related reference points, which is

FFS: Doppler frequency in background channel for monostatic sensing
The rays in a stochastic cluster with ZOA at BS less than D degree are dropped [with probability p, p=1] 
D=[90] for RMa, 
D=[60] for UMa
Note: this threshold for ZOA is not applicable to other sensing scenarios


[FL3] Proposal 5.4-3 
To generate the background channel, the power threshold (-25 dB) for removing clusters in step 6 in section 7.5, TR 38.901 is reused.


[FL3] Proposal 5.4-4-rev1 
The ISAC background channel can be generated between a sensing Tx and a sensing Rx or RP (relevant for monostatic case) via the following steps:
Step 1: generate a first set of clusters/rays according to TR 38.901(or other related TRs)
Step 2: generate a second set of NLOS clusters/rays according to TR 38.901 (or other related TRs), where the power of the second set of clusters/rays should be scaled down such that


(,   are the power of the n-th cluster from the first and second set, respectively).
Where, N is the number of clusters, M is the number of rays within each cluster, value of G relates to power
Option 1: N=360, M=1, G=0dB, with uniform delay and angle (only for mono-static case)
Supported by: Nokia
Option 2: N=[360 or 60], M=1, G = -25dB, no further change from 38.901, 36.777, 38.858 (i.e., utilizing the same DS, ASA, ASD, ZSA, ZSD, ,  as used for the first step)
Supported by: Xiaomi, ZTE, Lenovo, MTK, Qc, CMCC, IDCC, 
Note: the step 2 is an additional modeling component
FFS: in which communication scenario(s) low-power clusters need to be included


Friday (Apr. 11)
[H]Package proposal-rev1
[FL3] Proposal 5.2-1-rev3
On background channel for mono-static sensing, the following details are provided:
 reference points are dropped for one Tx, based on the Gamma distribution for distance and height of reference point.
The LOS AOD between Tx and the first reference point, which is denoted as AOD1, is generated based on uniform distribution .
The LOS AOD between Tx and the second reference point is AOD1 + 
The LOS AOD between Tx and the third reference point is AOD1 + 
The background channel is generated based on the channel generated as in existing TR between the real Tx and the reference point assuming NLOS condition.
The antenna field pattern and array orientation of reference point are set same as Tx. 
Arrival angles for both azimuth and elevation  and  are set equal to departure angles
The absolute delay model d3D and  as agreed for bistatic sensing for the same sensing scenario applies. 
Option 0: no scaling factor is applied to d3D
Supported by: Apple, SS, ZTE, OPPO, HW, MTK, CATT, SPRD, LGE, Xiaomi, 
Option 1: An offset is applied to d3D, i.e., d3D-c1
Supported by: Ericsson, 
Option 2: A scaling factor d_s is mulitplexed to d3D, i.e., d3D*d_s. d_s is a value within range [0, 1]. 
Supported by: Ericsson, 
Note: The adjustment of absolute delay doesn’t impact the generation of NLOS clusters between the Tx and each reference point
The mono-static background channel for the Tx would be sum of channels of the links between the Tx and all related reference points, which is

FFS: Doppler frequency in background channel for monostatic sensing
The rays in a stochastic cluster with ZOA at BS less than D degree are dropped [with probability p, p=1] 
D=[90] for RMa, 
D=[60] for UMa
Note: this threshold for ZOA is not applicable to other sensing scenarios


[FL3] Proposal 5.4-3 
To generate the background channel, the power threshold (-25 dB) for removing clusters in step 6 in section 7.5, TR 38.901 is reused.


[FL3] Proposal 5.4-4-rev1 
The ISAC background channel can be generated between a sensing Tx and a sensing Rx or RP (relevant for monostatic case) via the following steps:
Step 1: generate a first set of clusters/rays according to TR 38.901(or other related TRs)
Step 2: generate a second set of NLOS clusters/rays according to TR 38.901 (or other related TRs), where the power of the second set of clusters/rays should be scaled down such that


(,   are the power of the n-th cluster from the first and second set, respectively).
Where, N is the number of clusters, M is the number of rays within each cluster, value of G relates to power
Option 1: N=360, M=1, G=0dB, with uniform delay and angle (only for mono-static case)
Supported by: Nokia
Option 2: N=360, M=1, G = -25dB, no further change from 38.901, 36.777, 38.858 (i.e., utilizing the same DS, ASA, ASD, ZSA, ZSD, ,  as used for the first step)
Supported by: Xiaomi, ZTE, Lenovo, MTK, Qc, CMCC, IDCC, 
The step 2 is an additional modeling component
Note: applicability of low-power clusters to scenarios is part of evaluation phase
Supported by: Xiaomi, OPPO, LGE, QC, ZTE, SS, Huawei, 
FFS: in which communication scenario(s) low-power clusters need to be included
Supported by: Lenovo, Ericsson, 
No sub-bullet on note or FFS: 
Supported: CATT, MTK, ZTE, SS, LGE, Sony, Xiaomi, OPPO, Huawei, 



[H][FL3] Proposal 5.2-2-rev4 for working assumption
The values of the parameters to generated background channel for TRP monostatic and UE monostatic sensing for each sensing scenario are provided in the following table 
FFS parameter values for other scenarios
An email discussion/approval checking the values after April meeting is preferred, including validation for newly agreed parameters
The email discussion includes all scenarios, TRP monostatic and UE monostatic



[FL3] Proposal 5.5-4
The height of scattering point of a human is the geometry center of the human

[FL3] Proposal 5.5-3 for conclusion
There is offline consensus that no special handling on LOS probability is necessary for InF due to the height of scattering point of human. 


[FL3] Proposal 5.5-2-rev1
In sensing scenario UMi, UMa, RMa, if the height of a scattering point of target is less than 1.5m, for pathloss calculation, 
Option 1: the minimum d_BP is 10m. 
Nokia 
Option 2: the minimum d_BP is 0m. 
Ericsson, vivo
Option 4: use  in Table 7.4.1-1: Pathloss models in TR 38.901
HW, LGE, CATT, Samsung, ZTE, Xiaomi, OPPO, 

[FL3] Proposal 5.5-1 
For sensing scenario UMi, UMa, RMa, UMi-AV, UMa-AV and RMa-AV, the height of target is used to calculate the LOS probability and pathloss, regardless of the lower bound in the existing TRs that are referred to generate ISAC channel. 


[FL3] Proposal 6.3-1-rev1 
The pathloss of the ray specular reflected by an EO type 2 in the STX-SPST link or SPST-SRX link is calculated by , where 
 is a pathloss assuming a LOS condition for the STX-SPST link or SPST-SRX link
 is the total propagation distance due to EO type-2


[FL2] Proposal 5.10-2-rev2 for working assumption
To generate the absolute delay model for sensing scenarios Urban grid, highway and HST, for both target channel and background channel
For Urban grid, the values of parameters for  of scenarios UMa are reused. 
For Highway, the values of parameters for  of scenarios RMa and UMa are reused for FR1 and FR2 respectively. 
For HST, the values of parameters for  of scenarios RMa and UMa are reused for FR1 and FR2 respectively. 
Note: If significant problem is found by validation, we can change the distribution of 


[H][FL3] Proposal 7.4-1-rev1
On the relation between multiple scattering points of a target and spatial consistency
When spatial consistency is NOT implemented, channels of the multiple scattering points of a target is independently generated
OPPO, QC, CATT, Spreadtrum, SS, CMCC, Nokia
When multiple scattering points of target is modelled, spatial consistency is used
Huawei, ZTE, vivo, BUPT, DOCOMO, Ericsson, LG, IDCC, 
Spatial consistency, if enabled, for the links between BS/UT and multiple scattering points of a target are modelled as if multiple targets. 


[FL3] Proposal 4.1.2-1-rev1 
The bistatic RCS of UAV with small size is modelled as
Component A: same as component A of mono-static RCS for UAV of small size
Component B1: 
Option 1:  dB, where  is the bi-static angle between incident ray and scattered ray,  is within 0 and 180 degree
Supported by: HW, ZTE, LGE, CATT, Xiaomi, OPPO, SS, 
Option 2: 0dB
Supported by: vivo, 
Component B2: same as component B2 of mono-static RCS for UAV of small size


[FL3] Proposal 4.1.3-1 
The bistatic RCS of human with RCS model 1 is modelled as
Component A: same as component A of mono-static RCS for human with RCS model 1
Option 1:  dB, where  is the 3D bi-static angle between incident angle and scattered angle
Option 2: 0dB
Component B2: same as component B2 of mono-static RCS for human with RCS model 1


[FL3] Proposal 6.1-1-rev1 
EO type-2 is modelled in background channel if modelled in target channel
Supported by: HW, LG, Lenovo, SS, ZTE, Sony
EO type-2 is not modelled in background channel
Supported by: CATT, QC, vivo, SPRD, Ericsson, IDCC, DOCOMO, OPPO, Xiaomi, 


[FL3] Proposal 6.2-1-rev1 
Down-select in RAN1#120bis one option from the following options to determine the LOS condition of the Tx-target link and target-Rx link?
Option A: If type-2 EO is in the LOS ray of one link, the link is determined as NLOS condition, and otherwise use the LOS probability equation defined in existing TRs to determine the LOS/NLOS condition
Supported by: HW, ZTE, Sony, QC, LG, Xiaomi, MTK, Nokia, CMCC, Spreadtrum, OPPO, vivo, 
Option B: Use the LOS probability equation to determine the LOS/NLOS condition of one link, and then the impacts of type-2 EO is modelled by a blockage model
Supported by: Ericsson, CATT (without blockage model), Lenovo, IDCC, DOCOMO, 
Option C: Use the LOS probability equation to determine the LOS/NLOS condition of one link,
Supported by: CATT, Ericsson, Nokia, Lenovo, DOCOMO, IDCC,  
Note: If EO type-2 is agreed to be modelled in background channel, the agreed option is extended to LOS condition determination for background channel. 


[FL3] Proposal 7.1-3-rev2 
When spatial consistency is enabled, the set of remaining paths after path dropping after concatenation of Tx-target and target-Rx link 
Option 1: is not updated per simulation drop even if Tx, target, Rx positions change during simulation.
Option 2: can be updated even if Tx, target, Rx positions change during simulation.


[FL3] Proposal 7.6-1-rev3 for working assumption
Option 1: The existing horizontal correlation distance in Table 7.6.3.1-2 in TR38.901 is reused as vertical correlation distance for ISAC channel at least for UAV scenario, within same ‘Applicability range in terms of aerial UE height (defined in 36.777)’
Option 2: 3GPP assumes UAV height cannot change in a simulation drop, if spatial consistency is enabled.
Option 3: The existing horizontal correlation distance in Table 7.6.3.1-2 in TR38.901 is reused to model 3D spatial consistency for ISAC channel at least for UAV scenario, within same ‘Applicability range in terms of aerial UE height (defined in 36.777)’


Ask for email approval
[FL3] Proposal 4.2.1-1 
On the monostatic RCS of UAV of large size,
The values/pattern of component A*B1 are generated by the following parameters 

When  is in the range [0°,45° ] or [135°,180°], 
The standard deviation of component B2 is 2.50 dB


[FL3] Proposal 4.2.3-1 
On the monostatic RCS of AGV with single scattering point,
The values/pattern of component A*B1 are generated by the following parameters 

When  is in the range [0°,30° ), 
The standard deviation of component B2 is 2.51 dB

[FL3] Proposal 5.1-2 
In order to generate Tx-target link, target-Rx link and the background channel between a RSU-type UE and another node (TRP, pedestrian UE, vehicle UE, RSU-type UE), the following reference TRs are adopted



[FL3] Proposal 8.1-1-rev1  
The link-level channel for ISAC is generated by adding add one or more clusters representing target(s) to the existing CDL channel model
Values of parameters of the added cluster(s) can be discussed in performance evaluation stage
TDL channel model from exiting 38.901 is not enhanced for ISAC channel model


[FL3] Proposal 7.2-1
Spatial consistency is not modelled for
the links that are generated referring to channel models with parameter values of different communication scenarios
E.g., between TRP-target/UT link in one scenario and target/UT-UT link in another scenario
the background channels for TRP monostatic sensing of different TRPs


[FL3] Proposal 7.2-2
Spatial consistency is not modelled between TRP-target/UT link and target/UT-UT link for sensing scenario UMi, InH and InF


[FL2] Proposal 7.1-1
When spatial consistency is NOT enabled, the Tx/target/Rx position is unchanged in a simulation drop


[FL2] Proposal 4.3-1 
The same value of the component A is applied to the monostatic RCS and the bistatic RCS of a target
Exact value of component A is to be discussed per target



Proposed offline proposals
Monday (Apr. 7)
After Monday offline session

[FL1] Proposal 5.1-1-rev1 
In order to generate Tx-target link, target-Rx link and the background channel, The above table on reference TRs (excluding the already agreed part) is adopted for the mapping between reference TRs and a pair of nodes (STX, SRX, target) 
FFS RSU type UE


[FL1] Proposal 5.2-1-rev1
Confirm the previous working assumption on background channel for mono-static sensing with the following details:
 reference points are dropped for one Tx, based on the Gamma distribution for distance and height of reference point.
The LOS AOD between Tx and the first reference point is generated based on uniform distribution , and the gap of LOS AOD between the Tx and different reference points keeps as .
The background channel is generated based on the channel generated as in existing TR between the real Tx and the reference point assuming NLOS condition.
The antenna field pattern and array orientation of reference point are set same as Tx. 
Arrival angles for both azimuth and elevation  and  are set equal to departure angles
The absolute delay model [d3D and]  as agreed for bistatic sensing for the same sensing scenario applies. 
The mono-static background channel for the Tx would be sum of channels of the links between the Tx and all related reference points, which is

FFS: Doppler frequency in background channel for monostatic sensing
FFS: whether to add additional very low power clusters
FFS: any update to parameters e.g. angular distribution and delay spread


[FL1] Proposal 5.2-2-rev2
The values of the parameters to generated background channel for TRP monostatic and UE monostatic sensing for each sensing scenario are provided in the following table 
FFS parameter values for other scenarios


[FL1] Proposal 5.2-3-rev1
The small scale parameters used to generate the Tx-target link are respectively same as that of the target-Rx link for monostatic sensing. 

[FL1] Proposal 5.3-1-rev1 
Normalization on the product of three polarization matrixes of a direct/indirect path, i.e., CPMtx,sp,rx= CPMsp,rx . CPMsp . CPMtx,sp is supported
The scaling factor is 

[FL1] Proposal 5.4-2 
Power normalization of target channel after path dropping of the target channel is not supported

[FL1] Proposal 4.2.2-1-rev1 
On the monostatic RCS for human with RCS model 2
The monostatic RCS for a scattering point of the target is generated by
The values/pattern A*B1, i.e.,  is deterministic based on incident/scattered angles

Where,


FFS how many rows of the values/pattern A*B1 are defined for the target
Note: each row has a defined applicable range of  and 
Note: whether the RCS is elevation angle dependent or dependent on both elevation and horizontal angles can be separately discussed


[FL1] Proposal 4.5-1 
The following mean and standard deviation values of XPR of targets are agreed
UAV: (13.75, 7.07) dB
Human: (19.81, 4.25) dB
Vehicle: (21.12, 6.88) dB


[FL1] Proposal 4.1.1-2-rev1
For vehicle with single/multiple SPSTs, down select one option from the following options generating bistatic RCS. 
Option A:
The values/pattern of A*B1 of bistatic RCS is given by:

	where


 is applied to the  within 0~180 degrees. The k= 6 based on the measurement validation.  is the absolute angle between the incident angle and scattering angle within the plane of incident direction () and scattering direction ().
The angles of () are the projections of the bisector angle on the vertical plane and the horizontal plane, respectively.
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs
Supported by: Huawei, CATT, ZTE, Xiaomi, OPPO

Option B:
Define the following two functions


The values/pattern A*B1, denoted as  of the bistatic RCS for a SPST is determined by
A first peak of bi-static RCS centred in the back-scattering direction of the incident direction is calculated as

A second peak of bi-static RCS centred in the specular reflection direction of the incident angle is calculated as

, (it is a concave function) 
For the front of vehicle, k1 = 15, k2 = 1.65
For the back of vehicle, k1 = 17.5, k2 = 1.65
For the left or right of vehicle, k1 = 14.5, k2 = 1.55
For the roof of vehicle, FFS
 is within 0~180 degrees.  is the absolute angle between the incident angle and scattering angle within the plane of incident direction () and scattering direction ().
 is the specular reflection direction, 
The final bistatic RCS value for incident/scattered angles () is 
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs
Supported by: vivo, BUPT, ZTE, CMCC, DOCOMO 

Option C:
Define the following two functions


The values/pattern A*B1, denoted as  of the bistatic RCS for a SPST is determined by
A first peak of bi-static RCS centred in the back-scattering direction of the incident direction is calculated as

A second peak of bi-static RCS centred in the specular reflection direction of the incident angle is calculated as

, (it is a concave function) 
For the front of vehicle, k1 = 15, k2 = 1.65
For the back of vehicle, k1 = 17.5, k2 = 1.65
For the left or right of vehicle, k1 = 14.5, k2 = 1.55
For the roof of vehicle, FFS
 is within 0~180 degrees.  is the absolute angle between the incident angle and scattering angle within the plane of incident direction () and scattering direction ().
 is the specular reflection direction, 
The final bistatic RCS value for incident/scattered angles () is 
 is -Inf in Rel-19
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs
Supported by: vivo, LGE, QC, BUPT, 


[FL1] Proposal 4.1.1-1
No special handling of RCS values in the forward scattering directions in Rel-19 SI
The existing blockage model B is reused to model the blocking effect due to a target as an optional feature 
Applicable to the LOS/NLOS rays in the background channel of the target

Tuesday (Apr. 8)
After Tuesday offline session

[FL1] Proposal 4.1.1-2-rev2
For vehicle with single/multiple SPSTs, down select one option from the following options generating bistatic RCS. 
Option A:
The values/pattern of A*B1 of bistatic RCS is given by:

	where


 is applied to the  within 0~180 degrees. The k= 6 based on the measurement validation.  is the absolute angle between the incident angle and scattering angle within the plane of incident direction () and scattering direction ().

The angles of () are the projections of the bisector angle on the vertical plane and the horizontal plane, respectively.
 is -Inf in Rel-19
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs
Supported by: Huawei, CATT, ZTE, Xiaomi, OPPO, LGE, Samsung, Nokia, 

Option B:
Define the following two functions


The values/pattern A*B1, denoted as  of the bistatic RCS for a SPST is determined by
A first peak of bi-static RCS centred in the back-scattering direction of the incident direction is calculated as

A second peak of bi-static RCS centred in the specular reflection direction of the incident angle is calculated as

, (it is a concave function) 
For the front of vehicle, k1 = 15, k2 = 1.65
For the back of vehicle, k1 = 17.5, k2 = 1.65
For the left or right of vehicle, k1 = 14.5, k2 = 1.55
For the roof of vehicle, FFS
 is within 0~180 degrees.  is the absolute angle between the incident angle and scattering angle within the plane of incident direction () and scattering direction ().
 is the specular reflection direction, 
The final bistatic RCS value for incident/scattered angles () is 
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs
Supported by: vivo, BUPT, ZTE, CMCC, DOCOMO 

Option C:
Define the following two functions


The values/pattern A*B1, denoted as  of the bistatic RCS for a SPST is determined by
A first peak of bi-static RCS centred in the back-scattering direction of the incident direction is calculated as

A second peak of bi-static RCS centred in the specular reflection direction of the incident angle is calculated as

, (it is a concave function) 
For the front of vehicle, k1 = 15, k2 = 1.65
For the back of vehicle, k1 = 17.5, k2 = 1.65
For the left or right of vehicle, k1 = 14.5, k2 = 1.55
For the roof of vehicle, FFS
 is within 0~180 degrees.  is the absolute angle between the incident angle and scattering angle within the plane of incident direction () and scattering direction ().
 is the specular reflection direction, 
The final bistatic RCS value for incident/scattered angles () is 
 is -Inf in Rel-19
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs
Supported by: vivo, LGE, QC, BUPT, CMCC, DOCOMO, ZTE

Wednesday (Apr. 9)

After Wed offline session

[FL2] Proposal 4.1.1-2-rev3
For vehicle with single/multiple scattering points, down select one option  generating bistatic RCS. 

Option C:
Define the following two functions


The values/pattern A*B1, denoted as  of the bistatic RCS for a SPST is determined by
A first peak of bi-static RCS centred in the back-scattering direction of the incident direction is calculated as

A second peak of bi-static RCS centred in the specular reflection direction of the incident angle is calculated as

, (it is a concave function) 
For the front of vehicle, k1 = 15, k2 = 1.65
For the back of vehicle, k1 = 17.5, k2 = 1.65
For the left or right of vehicle, k1 = 14.5, k2 = 1.55
For the roof of vehicle, FFS
 is within 0~180 degrees.  is the absolute angle between the incident angle and scattering angle within the plane of incident direction () and scattering direction ().
 is the specular reflection direction, 
The final bistatic RCS value for incident/scattered angles () is 
The effect of forward scattering  is -Inf in Rel-19
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs


Option D:
The values/pattern of A*B1 of bistatic RCS is given by:

	where


 is applied to the  within 0~180 degrees. k1= 6 and k2=1.  is the absolute bistatic angle between the incident and scattering within the plane of incident direction () and scattering direction ().
The angles of () are the projections of the bisector angle on the vertical plane and the horizontal plane, respectively.
FFS: bisector angle when  is 180 degrees
The effect of forward scattering  is -Inf in Rel-19
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs
FFS: how to avoid angular discontinuity


Method 1：
To address the issue of discontinuity, 

where：




Finally, the formula can be simplified to:


Method 2：


where：



[FL2] Proposal 5.2-1-rev2
On background channel for mono-static sensing, the following details are provided:
 reference points are dropped for one Tx, based on the Gamma distribution for distance and height of reference point.
The LOS AOD between Tx and the first reference point, which is denoted as AOD1, is generated based on uniform distribution .
The LOS AOD between Tx and the second reference point is AOD1 + 
The LOS AOD between Tx and the third reference point is AOD1 + 
The background channel is generated based on the channel generated as in existing TR between the real Tx and the reference point assuming NLOS condition.
The antenna field pattern and array orientation of reference point are set same as Tx. 
Arrival angles for both azimuth and elevation  and  are set equal to departure angles
The absolute delay model d3D and  as agreed for bistatic sensing for the same sensing scenario applies. 
The mono-static background channel for the Tx would be sum of channels of the links between the Tx and all related reference points, which is

FFS: Doppler frequency in background channel for monostatic sensing
FFS: whether/howto add additional very low power clusters
FFS: any update to parameters e.g. angular distribution and delay spread



[FL2] Proposal 5.4-3 
To generate the background channel, the power threshold for removing clusters in step 6 in section 7.5, TR 38.901 is reused


[FL2] Proposal 5.4-4-rev1 
The ISAC background channel can be generated between a sensing Tx and a sensing Rx or RP (relevant for monostatic case) via the following steps:
Step 1: generate a first set of clusters/rays according to TR 38.901(or other related TRs)
Step 2: generate a second set of NLOS clusters/rays according to TR 38.901 (or other related TRs), where the power of the second set of clusters/rays should be scaled down such that


(,   are the power of the n-th cluster from the first and second set, respectively).
Where, N is the number of clusters, M is the number of rays within each cluster, value of G relates to power
Option 1: N=360, M=1, G=0dB, with uniform delay and angle (only for mono-static case)
Supported by: Nokia
Option 2: N=60, M=1, G = -25dB, no further change from 38.901 (i.e., utilizing the same DS, ASA, ASD, ZSA, ZSD, ,  as used for the first step)
Supported by: Xiaomi, ZTE, Lenovo, MTK, Qc, CMCC, IDCC, 
Note: the step 2 is an additional modeling component


[FL2] Proposal 5.2-2-rev2 for working assumption
The values of the parameters to generated background channel for TRP monostatic and UE monostatic sensing for each sensing scenario are provided in the following table 
FFS parameter values for other scenarios
An email discussion checking the values are preferred



Thursday (Apr. 10)

After Thursday offline session

[H]Package proposal
[FL3] Proposal 5.2-1-rev3
On background channel for mono-static sensing, the following details are provided:
 reference points are dropped for one Tx, based on the Gamma distribution for distance and height of reference point.
The LOS AOD between Tx and the first reference point, which is denoted as AOD1, is generated based on uniform distribution .
The LOS AOD between Tx and the second reference point is AOD1 + 
The LOS AOD between Tx and the third reference point is AOD1 + 
The background channel is generated based on the channel generated as in existing TR between the real Tx and the reference point assuming NLOS condition.
The antenna field pattern and array orientation of reference point are set same as Tx. 
Arrival angles for both azimuth and elevation  and  are set equal to departure angles
The absolute delay model d3D and  as agreed for bistatic sensing for the same sensing scenario applies. 
Option 0: no scaling factor is applied to d3D
Supported by: Apple, SS, ZTE, OPPO, HW, MTK, CATT, SPRD, LGE, Xiaomi, 
Option 1: An offset is applied to d3D, i.e., d3D-c1
Supported by: Ericsson, 
Option 2: A scaling factor d_s is mulitplexed to d3D, i.e., d3D*d_s. d_s is a value within range [0, 1]. 
Supported by: Ericsson, 
Note: The adjustment of absolute delay doesn’t impact the generation of NLOS clusters between the Tx and each reference point
The mono-static background channel for the Tx would be sum of channels of the links between the Tx and all related reference points, which is

FFS: Doppler frequency in background channel for monostatic sensing
The rays in a stochastic cluster with ZOA at BS less than D degree are dropped [with probability p, p=1] 
D=[90] for RMa, 
D=[60] for UMa
Note: this threshold for ZOA is not applicable to other sensing scenarios


[FL3] Proposal 5.4-3 
To generate the background channel, the power threshold (-25 dB) for removing clusters in step 6 in section 7.5, TR 38.901 is reused.


[FL3] Proposal 5.4-4-rev1 
The ISAC background channel can be generated between a sensing Tx and a sensing Rx or RP (relevant for monostatic case) via the following steps:
Step 1: generate a first set of clusters/rays according to TR 38.901(or other related TRs)
Step 2: generate a second set of NLOS clusters/rays according to TR 38.901 (or other related TRs), where the power of the second set of clusters/rays should be scaled down such that


(,   are the power of the n-th cluster from the first and second set, respectively).
Where, N is the number of clusters, M is the number of rays within each cluster, value of G relates to power
Option 1: N=360, M=1, G=0dB, with uniform delay and angle (only for mono-static case)
Supported by: Nokia
Option 2: N=360, M=1, G = -25dB, no further change from 38.901, 36.777, 38.858 (i.e., utilizing the same DS, ASA, ASD, ZSA, ZSD, ,  as used for the first step)
Supported by: Xiaomi, ZTE, Lenovo, MTK, Qc, CMCC, IDCC, 
The step 2 is an additional modeling component
Note: applicability of low-power clusters to scenarios is part of evaluation phase
Supported by: Xiaomi, OPPO, LGE, QC, ZTE, SS, Huawei, 
FFS: in which communication scenario(s) low-power clusters need to be included
Supported by: Lenovo, Ericsson, 
No sub-bullet on note or FFS: 
Supported: CATT, MTK, ZTE, SS, LGE, Sony, Xiaomi, OPPO, Huawei, 


[H][FL3] Proposal 5.2-2-rev3 for working assumption
The values of the parameters to generated background channel for TRP monostatic and UE monostatic sensing for each sensing scenario are provided in the following table 
FFS parameter values for other scenarios
An email discussion/approval checking the values after April meeting is preferred, including validation for newly agreed parameters
The email discussion includes all scenarios, TRP monostatic and UE monostatic


[FL3] Proposal 4.1.2-1 
The bistatic RCS of UAV with small size is modelled as
Component A: same as component A of mono-static RCS for UAV of small size
Component B1: 
Option 1:  dB, where  is the bi-static angle between incident ray and scattered ray,  is within 0 and 180 degree
Supported by: HW, ZTE, LGE, CATT, Xiaomi, OPPO, SS, 
Option 2: 0dB
Supported by: vivo, 
Component B2: same as component B2 of mono-static RCS for UAV of small size


[FL3] Proposal 4.1.3-1 
The bistatic RCS of human with RCS model 1 is modelled as
Component A: same as component A of mono-static RCS for human with RCS model 1
Option 1:  dB, where  is the 3D bi-static angle between incident angle and scattered angle
Option 2: 0dB
Component B2: same as component B2 of mono-static RCS for human with RCS model 1


Package proposal 
[FL3] Proposal for height of scattering point
The height of scattering point of a human is the geometry center of the human

[FL3] Proposal 5.5-2 for pathloss
In sensing scenario UMi, UMa, RMa, if the height of a scattering point of target is less than 1.5m, for pathloss calculation, 
Option 1: the minimum d_BP is 10m. 
Nokia 
Option 2: the minimum d_BP is 0m. 
Ericsson, vivo
Option 4: use  in Table 7.4.1-1: Pathloss models in TR 38.901
HW, LGE, CATT, Samsung, ZTE, Xiaomi, OPPO, 

Offline conclusion
There is offline consensus that no special handling on LOS probability is necessary for InF due to the height of scattering point of human. 


[FL2] Proposal 5.10-2-rev1 for working assumption
To generate the absolute delay model for sensing scenarios Urban grid, highway and HST, for both target channel and background channel
For Urban grid, the values of parameters for  of scenarios UMa are reused. 
For Highway, the values of parameters for  of scenarios RMa and UMa are reused for FR1 and FR2 respectively. 
For HST, the values of parameters for  of scenarios RMa and UMa are reused for FR1 and FR2 respectively. 
Note: If significant problem is found by validation, we can change the distribution of 


[FL3] Proposal 6.3-1 
The pathloss of the ray specular reflected by an EO type 2 in the STX-SPST link or SPST-SRX link is calculated by , where 
 is a pathloss assuming a LOS condition for the STX-SPST link or SPST-SRX link
 is the total propagation distance due to EO type-2


[FL3] Proposal 6.1-1 
EO type-2 is modelled in background channel if modelled in target channel
Supported by: HW, LG, Lenovo, SS, ZTE, Sony
EO type-2 is not modelled in background channel
Supported by: CATT, QC, vivo, SPRD, Ericsson, IDCC, DOCOMO, OPPO, Xiaomi, 


[FL3] Proposal 6.2-1 
Down-select in RAN1#120bis one option from the following options to determine the LOS condition of the Tx-target link and target-Rx link?
Option A: If type-2 EO is in the LOS ray of one link, the link is determined as NLOS condition, and otherwise use the LOS probability equation defined in existing TRs to determine the LOS/NLOS condition
Supported by: HW, ZTE, Sony, QC, LG, Xiaomi, MTK, Nokia, CMCC, Spreadtrum, OPPO, vivo, 
Option B: Use the LOS probability equation to determine the LOS/NLOS condition of one link, and then the impacts of type-2 EO is modelled by a blockage model
Supported by: Ericsson, CATT (without blockage model), Lenovo, IDCC, DOCOMO, 
Option C: Use the LOS probability equation to determine the LOS/NLOS condition of one link,
Supported by: CATT, Ericsson, Nokia, Lenovo, DOCOMO, IDCC,  
Note: If EO type-2 is agreed to be modelled in background channel, the agreed option is extended to LOS condition determination for background channel. 



[H][FL3] Proposal 7.4-1
On the relation between multiple scattering points of a target and spatial consistency
When spatial consistency is NOT implemented, channels of the multiple scattering points of a target is independently generated
OPPO, QC, CATT, Spreadtrum, SS, CMCC, Nokia
When multiple scattering points of target is modelled, spatial consistency is used
Huawei, ZTE, vivo, BUPT, DOCOMO, Ericsson, LG, IDCC, 
Spatial consistency, if enabled, for the links between BS/UT and multiple scattering points of a target are modelled as if multiple targets. 


[FL3] Proposal 7.1-3-rev1 
When spatial consistency is enabled, the set of remaining paths after path dropping after concatenation of Tx-target and target-Rx link 
Option 1: is not updated per simulation drop even if Tx, target, Rx positions change during simulation.
Option 2: can be updated even if Tx, target, Rx positions change during simulation.


[FL3] Proposal 7.6-1-rev2 for working assumption
Option 1: The existing horizontal correlation distance in Table 7.6.3.1-2 in TR38.901 is reused as vertical correlation distance for ISAC channel at least for UAV scenario, within same ‘Applicability range in terms of aerial UE height (defined in 36.777)’
Option 2: 3GPP assumes UAV height cannot change in a simulation drop, if spatial consistency is enabled.
Option 3: The existing horizontal correlation distance in Table 7.6.3.1-2 in TR38.901 is reused to model 3D spatial consistency for ISAC channel at least for UAV scenario, within same ‘Applicability range in terms of aerial UE height (defined in 36.777)’


Ask for email approval

[FL3] Proposal 4.2.1-1 
On the monostatic RCS of UAV of large size,
The values/pattern of component A*B1 are generated by the following parameters 

When  is in the range [0°,45° ] or [135°,180°], 
The standard deviation of component B2 is 2.50 dB


[FL3] Proposal 4.2.3-1 
On the monostatic RCS of AGV with single scattering point,
The values/pattern of component A*B1 are generated by the following parameters 

When  is in the range [0°,30° ), 
The standard deviation of component B2 is 2.51 dB

[FL3] Proposal 5.1-2 
In order to generate Tx-target link, target-Rx link and the background channel between a RSU-type UE and another node (TRP, pedestrian UE, vehicle UE, RSU-type UE), the following reference TRs are adopted



[FL3] Proposal 8.1-1-rev1  
The link-level channel for ISAC is generated by adding add one or more clusters representing target(s) to the existing CDL channel model
Values of parameters of the added cluster(s) can be discussed in performance evaluation stage
TDL channel model from exiting 38.901 is not enhanced for ISAC channel model


[FL3] Proposal 7.2-1
Spatial consistency is not modelled for
the links that are generated referring to channel models with parameter values of different communication scenarios
E.g., between TRP-target/UT link in one scenario and target/UT-UT link in another scenario
the background channels for TRP monostatic sensing of different TRPs


[FL3] Proposal 7.2-2
Spatial consistency is not modelled between TRP-target/UT link and target/UT-UT link for sensing scenario UMi, InH and InF


[FL2] Proposal 7.1-1
When spatial consistency is NOT enabled, the Tx/target/Rx position is unchanged in a simulation drop


[FL2] Proposal 4.3-1 
The same value of the component A is applied to the monostatic RCS and the bistatic RCS of a target
Exact value of component A is to be discussed per target


Physical object model
E//: Angle-dependent RCS model of a target is provided for a given target’s local coordinate system
[H] Bistatic RCS
General on bistatic RCS

Summary on company views

Design issues on bistatic RCS
Whether/how to model a peak in the specular reflection direction (RCS_s())?
Yes: QC, E//, NIST, vivo, BUPT, ZTE, Xiaomi, Spreadtrum
What is the trend of the peak values with the change of incident direction?
roughly monotone: HW, ZTE
concave function: vivo, BUPT 
Whether/how to model a peak of the back scattering in the incident direction, which is equal to the monostatic RCS in the incident direction (RCS_i())?
Yes: QC, vivo, BUPT
Whether/how to model a shadow or peak in the forward scattering region?
peak: QC, LGE, vivo, BUPT, Apple
shadow: QC, HW, NIST, ZTE, 
To combine all the bi-static RCS components, select the bi-static RCS component with the maximum RCS value, : vivo, BUPT

CATT: min{,  RCS_MIN}
CT, LGE: 
Nokia
For bistatic RCS, use the bistatic angle to define at least two angular regions.
When bistatic angle , the bistatic RCS , at least , where  is monostatic RCS value.
When  is close to 180 degree, further study how to model bistatic RCS with forward scattering links.
LGE: 3 angular regions
LGE: Model the forward scattering RCS as a deterministic function , where angles  are determined w.r.t. the Tx to target line, Daz and Del are the effective extents of sensing target in azimuth and elevation domains, respectively. Define the angular width of the forward scattering region centered at  as  [rad].
E//: The bistatic RCS model should have a small, close-to-zero value in the forward scattering region if shadowing of the object is modelled using a blocker.

Shadows behind targets
Shadows behind targets should be odellin: Ericsson
Shadow is distance dependent: Ericsson

Ericsson: sensing Rx is likely to locate in the near field of a large target, where shadow effect needs to be taken into account

To model a shadow
large RCS in the shadow region than in other directions and with opposite phase to that of background channel so that H_target≈-H_background and H_ISAC=H_background+H_target becomes small
Ericsson
conflict with the agreement on scalar RCS odelling
without phase, it creates an energy increase behind the target, which breaks the laws of physics
The RCS needs to be dependent on both Tx-target distance and target-Rx distance to generate the correct “depth” of the shadow
Blockage model so that  is reduced in the shadow region: E//, NIST
E//: Blocking can simplify RCS modelling tremendously. Without the very strong forward scattering component, RCS is much easier to model
E//, Lenovo: The blockage of one target can be considered in the Tx-target and/or target-Rx links of another target channel depending on sensing mode.

NIST: We should explore how to model forward-scattering beyond shadowing region. Option 1: Continue using the blockage model, which models the combined behaviour of LOS and diffraction paths. Option 2: Use an effective RCS model based on target diffraction paths to reduce modelling complexity.

Diffraction / blockage model
The existing blockage model B is reused to model the blocking effect due to a target as an optional feature
Applicable to the LOS/NLOS rays in the background channel of the target
Applicable to the LOS/NLOS rays in the Tx-target and target-Rx link of the other target
Supported by: Ericsson, Lenovo, IDC, SONY, BUPT, DOCOMO, NIST
OK for optional feature: HW, Nokia, LGE, CATT, Samsung, QC
NO: vivo, ZTE

NVIDIA: blockage and forward scattering between sensing targets should be modelled in the target channel

Reciprocity
E//: The modelled RCS should be reciprocal 

[Moderator’s note] It is quite controversial whether/how to model diffraction/forward scattering. Some validation results show it is a peak in the forward scattering region, while other validation results indicate it is a shadow. The proposal on modeling a peak or a shadow is also diverged. The reason for the different measurements may be due to the assumed target to receiver distance. 
Considering the limited remaining Tus of the study item, it is generally not preferred to model distance dependent RCS for diffraction/forward scattering. 
As discussed by Ericsson and NIST, modelling a large RCS for forward scattering results in high total power received at the receiver, since the LOS ray in the background channel is modelled in the ISAC channel too. Given blockage model B can serve the purpose to model diffraction, we may not pursue a special handling on RCS for forward scattering in the limited remaining time for study. 
[FL1] Proposal 4.1.1-1
No special handling of RCS values in the forward scattering directions in Rel-19 SI
The existing blockage model B is reused to model the blocking effect due to a target as an optional feature 
Applicable to the LOS/NLOS rays in the background channel of the target


[Moderator’s note] Based on the companies’ inputs, the following two options (mainly for vehicle) get some supports. Both options have the following merits
The bistatic RCS for the backscatter of incident direction is equal to the monostatic RCS in the same direction
It generates a peak at the specular reflection direction
Both options will generate one peak at the backscatter of incident direction, up to 3 peaks for specular reflection since an incident ray can luminate up to 3 surfaces of the vehicle, e.g., front/left/roof for a transmitter in left-front direction with 
Note: for easy discussion, I now rename the following two options as Option A and Option B. 

For Option B, please provide your view on Alt 1 and Alt 2 to generate the peak RCS values of specular reflection direction. Alt 1 is originally proposed by vivo/BUPT, while Alt 2 is added by the moderator to align Option A/B. Not sure if Alt 2 can be a compromise since it uses a spirit of Option A. Other alternatives are not precluded at the moment. 

[FL1] Proposal 4.1.1-2
For vehicle with single/multiple SPSTs, down select one option from the following options generating bistatic RCS. 
Option A:
The values/pattern of A*B1 of bistatic RCS is given by:

	where
,
.
 is applied to the  within 0~180 degrees. The k= 6 based on the measurement validation.  is the absolute angle between the incident angle and scattering angle within the plane of incident direction () and scattering direction ().
The angles of () are the projections of the bisector angle on the vertical plane and the horizontal plane, respectively.
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs

Option B:
Define the following two functions


The values/pattern A*B1, denoted as  of the bistatic RCS for a SPST is determined by
A first peak of bi-static RCS centred in the back-scattering direction of the incident direction is calculated as

A second peak of bi-static RCS centred in the specular reflection direction of the incident angle is calculated as

Alt 1: , (it is a concave function) 
For the front of vehicle, k1 = 15, k2 = 1.65
For the back of vehicle, k1 = 17.5, k2 = 1.65
For the left or right of vehicle, k1 = 14.5, k2 = 1.55
For the roof of vehicle, FFS
Alt 2:  (decreasing with increased bistatic angles)
The k= 6 based on the measurement validation.
 is within 0~180 degrees.  is the absolute angle between the incident angle and scattering angle within the plane of incident direction () and scattering direction ().
 is the specular reflection direction, 
The final bistatic RCS value for incident/scattered angles () is 
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs



[FL1] Proposal 4.1.1-2-rev1
For vehicle with single/multiple SPSTs, down select one option from the following options generating bistatic RCS. 
Option A:
The values/pattern of A*B1 of bistatic RCS is given by:

	where


 is applied to the  within 0~180 degrees. The k= 6 based on the measurement validation.  is the absolute angle between the incident angle and scattering angle within the plane of incident direction () and scattering direction ().
The angles of () are the projections of the bisector angle on the vertical plane and the horizontal plane, respectively.
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs
Supported by: Huawei, CATT, ZTE, Xiaomi, OPPO

Option B:
Define the following two functions


The values/pattern A*B1, denoted as  of the bistatic RCS for a SPST is determined by
A first peak of bi-static RCS centred in the back-scattering direction of the incident direction is calculated as

A second peak of bi-static RCS centred in the specular reflection direction of the incident angle is calculated as

, (it is a concave function) 
For the front of vehicle, k1 = 15, k2 = 1.65
For the back of vehicle, k1 = 17.5, k2 = 1.65
For the left or right of vehicle, k1 = 14.5, k2 = 1.55
For the roof of vehicle, FFS
 is within 0~180 degrees.  is the absolute angle between the incident angle and scattering angle within the plane of incident direction () and scattering direction ().
 is the specular reflection direction, 
The final bistatic RCS value for incident/scattered angles () is 
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs
Supported by: vivo, BUPT, ZTE, CMCC, DOCOMO 

Option C:
Define the following two functions


The values/pattern A*B1, denoted as  of the bistatic RCS for a SPST is determined by
A first peak of bi-static RCS centred in the back-scattering direction of the incident direction is calculated as

A second peak of bi-static RCS centred in the specular reflection direction of the incident angle is calculated as

, (it is a concave function) 
For the front of vehicle, k1 = 15, k2 = 1.65
For the back of vehicle, k1 = 17.5, k2 = 1.65
For the left or right of vehicle, k1 = 14.5, k2 = 1.55
For the roof of vehicle, FFS
 is within 0~180 degrees.  is the absolute angle between the incident angle and scattering angle within the plane of incident direction () and scattering direction ().
 is the specular reflection direction, 
The final bistatic RCS value for incident/scattered angles () is 
 is -Inf
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs
Supported by: vivo, LGE, QC, BUPT, 


[Moderator’s note] Further revised based on offline discussions

[FL2] Proposal 4.1.1-2-rev2
For vehicle with single/multiple SPSTs, down select one option from the following options generating bistatic RCS. 
Option A:
The values/pattern of A*B1 of bistatic RCS is given by:

	where


 is applied to the  within 0~180 degrees. The k= 6 based on the measurement validation.  is the absolute angle between the incident angle and scattering angle within the plane of incident direction () and scattering direction ().
The angles of () are the projections of the bisector angle on the vertical plane and the horizontal plane, respectively.
The effect of forward scattering  is -Inf in Rel-19
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs
Supported by: Huawei, CATT, ZTE, Xiaomi, OPPO, LGE, Samsung, Nokia, 

Option B:
Define the following two functions


The values/pattern A*B1, denoted as  of the bistatic RCS for a SPST is determined by
A first peak of bi-static RCS centred in the back-scattering direction of the incident direction is calculated as

A second peak of bi-static RCS centred in the specular reflection direction of the incident angle is calculated as

, (it is a concave function) 
For the front of vehicle, k1 = 15, k2 = 1.65
For the back of vehicle, k1 = 17.5, k2 = 1.65
For the left or right of vehicle, k1 = 14.5, k2 = 1.55
For the roof of vehicle, FFS
 is within 0~180 degrees.  is the absolute angle between the incident angle and scattering angle within the plane of incident direction () and scattering direction ().
 is the specular reflection direction, 
The final bistatic RCS value for incident/scattered angles () is 
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs
Supported by: vivo, BUPT, ZTE, CMCC, DOCOMO 

Option C:
Define the following two functions


The values/pattern A*B1, denoted as  of the bistatic RCS for a SPST is determined by
A first peak of bi-static RCS centred in the back-scattering direction of the incident direction is calculated as

A second peak of bi-static RCS centred in the specular reflection direction of the incident angle is calculated as

, (it is a concave function) 
For the front of vehicle, k1 = 15, k2 = 1.5
For the back of vehicle, k1 = 17.5, k2 = 1.65
For the left or right of vehicle, k1 = 14.5, k2 = 1.55
For the roof of vehicle, 
 is within 0~180 degrees.  is the absolute angle between the incident angle and scattering angle within the plane of incident direction () and scattering direction ().
 is the specular reflection direction, 

The final bistatic RCS value for incident/scattered angles () is 
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs
Supported by: vivo, LGE, QC, BUPT, CMCC, DOCOMO, ZTE



[FL2] Proposal 4.1.1-2-rev3
For vehicle with single/multiple scattering points, down select one option  generating bistatic RCS. 

Option C:
Define the following two functions


The values/pattern A*B1, denoted as  of the bistatic RCS for a SPST is determined by
A first peak of bi-static RCS centred in the back-scattering direction of the incident direction is calculated as

A second peak of bi-static RCS centred in the specular reflection direction of the incident angle is calculated as

, (it is a concave function) 
For the front of vehicle, k1 = 15, k2 = 1.65
For the back of vehicle, k1 = 17.5, k2 = 1.65
For the left or right of vehicle, k1 = 14.5, k2 = 1.55
For the roof of vehicle, FFS
 is within 0~180 degrees.  is the absolute angle between the incident angle and scattering angle within the plane of incident direction () and scattering direction ().
 is the specular reflection direction, 
The final bistatic RCS value for incident/scattered angles () is 
The effect of forward scattering  is -Inf in Rel-19
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs


Option D:
The values/pattern of A*B1 of bistatic RCS is given by:

	where


 is applied to the  within 0~180 degrees. k1= 6 and k2=1.  is the absolute bistatic angle between the incident and scattering within the plane of incident direction () and scattering direction ().
When the β is 180 degrees, the bi-static RCS value is the minimum value from the bi-static RCS pattern, i.e., G_max-σ_max-k.
The angles of () are the projections of the bisector angle on the vertical plane and the horizontal plane, respectively.
FFS: bisector angle when  is 180 degrees
The effect of forward scattering  is -Inf in Rel-19
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs
FFS: how to avoid angular discontinuity


[Moderator’s note] Revised in Wed offline session. Note: I now merge method 1 proposed by BUPT to the procedure of Option D and name it as Option D2 for conveniency. Let’s wait for validation results and comments. 

[FL3] Proposal 4.1.1-2-rev4
For vehicle with single/multiple scattering points, down select one option between option D and D2 for generating bistatic RCS. 

Option D:
The values/pattern of A*B1 of bistatic RCS is given by:

	where


 is applied to the  within 0~180 degrees. k1= 6 and k2=1.  is the absolute bistatic angle between the incident and scattering within the plane of incident direction () and scattering direction ().
The angles of () are the projections of the bisector angle on the vertical plane and the horizontal plane, respectively.
FFS: bisector angle when  is 180 degrees
The effect of forward scattering  is -Inf in Rel-19
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs
FFS: how to avoid angular discontinuity


Option D2
The values/pattern of A*B1 of bistatic RCS is given by:

where：



Finally, the formula can be simplified to:

 is applied to the  within 0~180 degrees.  is the absolute bistatic angle between the incident and scattering within the plane of incident direction () and scattering direction ().
The angles of () are the projections of the bisector angle on the vertical plane and the horizontal plane, respectively.
FFS: bisector angle when  is 180 degrees
The effect of forward scattering  is -Inf in Rel-19
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs
FFS: how to avoid angular discontinuity



[FL3] Proposal 4.1.1-2-rev5 for working assumption
For vehicle with single/multiple scattering points, the bistatic RCS is generated by
Option D:
The values/pattern of A*B1 of bistatic RCS is given by:

	where


 is applied to the  within 0~180 degrees. k1= 6 and k2=1.  is the absolute bistatic angle between the incident and scattering within the plane of incident direction () and scattering direction ().
The angles of () are the projections of the bisector angle on the vertical plane and the horizontal plane, respectively.
FFS: bisector angle when  is 180 degrees
The effect of forward scattering  is -Inf in Rel-19
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs
FFS: how to avoid angular discontinuity
Continue study on a new formula for  to resolve the issue of angular discontinuity. 
The new formula should retain following property: the linear bistatic RCS for a vehicle with single scattering point is the sum of the bistatic RCS of the multiple scattering points of the vehicle
the following formula can be a reference for the study 

 

[Moderator’s note] Agreed as working assumption in Thursday online 
Working assumption
For vehicle with single/multiple scattering points, the bistatic RCS is generated by
Option D:
The values/pattern of A*B1 of bistatic RCS is given by:

	where


 is applied to the  within 0~180 degrees. k1= 6 and k2=[1 or 1.65].  is the absolute bistatic angle between the incident ray and scattering ray within the plane of incident direction () and scattering direction ().
The angles of () are the projections of the bisector angle on the vertical plane and the horizontal plane, respectively.
FFS: RCS value when  is 180 degrees
The effect of forward scattering  is -Inf in Rel-19
5 sets of parameters Applicable Range of  and Applicable Range of  are applicable as defined for the monostatic RCS of vehicle with single/multiple SPSTs
FFS: how to avoid angular discontinuity
Continue study on a new formula for  to resolve the issue of angular discontinuity. 
The new formula should retain following property: the linear bistatic RCS for a vehicle with single scattering point is the sum of the bistatic RCS of the multiple scattering points of the vehicle
the following formula can be a reference for the study 



[Moderator’s note] Multiple companies propose that there is no specular reflection for human. One company prefer to model specular reflection for human. But please check if the proposal based on majority view is acceptable. 
[FL2] Proposal 4.1.1-3 for conclusion
No peak of bistatic RCS values is observed in the specular reflection direction for human



[Moderator’s note] For blockage model B, the proponents propose it not only for background channel, but also for interaction between targets. This is the second part of the proposal. Please check if it is agreeable. 
[FL1] Proposal 4.1.1-4 
The existing blockage model B is reused to model the blocking effect due to a target as an optional feature
Applicable to the LOS/NLOS rays in the Tx-target and target-Rx link of the other target



Framework/values for UAV
Summary on company views


CMCC


BUPT, vivo
The bi-static and mono-static RCS model share the same mathematical model at least for small UAV and human.

[Moderator’s note] Better to check if more inputs are available. 

[FL1] Question 4.1.2-1 
If any new results are available, please provide your inputs on values/pattern of A*B1 and (mean, standard deviation) of B2 for UAV of small size


[FL3] Proposal 4.1.2-1 
The bistatic RCS of UAV with small size is modelled as
Component A: same as component A of mono-static RCS for UAV of small size
Component B1:  where  is the 3D bi-static angle between incident angle and scattered angle
Component B2: same as component B2 of mono-static RCS for UAV of small size



[FL3] Proposal 4.1.2-1-rev1 
The bistatic RCS of UAV with small size is modelled as
Component A: same as component A of mono-static RCS for UAV of small size
Component B1: 
Option 1:  dB, where  is the bi-static angle between incident ray and scattered ray,  is within 0 and 180 degree
Supported by: HW, ZTE, LGE, CATT, Xiaomi, OPPO, SS, 
Option 2: 0dB
Supported by: vivo, 
Component B2: same as component B2 of mono-static RCS for UAV of small size


[FL1] Question 4.1.2-2 
If any new results are available, please provide your inputs on values/pattern of A*B1 and (mean, standard deviation) of B2 for UAV of large size




Framework/values for human 
Summary on company views



E//: To model the scattering off an upright human, linear , where  is an attenuation factor defined in terms of the bistatic angle  as  and  is a modified version of the antenna radiation pattern from TR38.901 defined in decibel scale as follows .
AT&T: For bistatic sensing, to model the RCS of an adult human target with single scattering point
A is mean RCS value given -14.4 dBsm
B2 is modelled using a log-normal distribution with mean 0 dB and standard deviation of 6.7


[Moderator’s note] Better to check if more inputs are available. 

[FL1] Question 4.1.3-1 
If any new results are available, please provide your inputs on values/pattern of A*B1 and (mean, standard deviation) of B2 for human with RCS model 1


[FL3] Proposal 4.1.3-1 
The bistatic RCS of human with RCS model 1 is modelled as
Component A: same as component A of mono-static RCS for human with RCS model 1
Component B1:  where  is the 3D bi-static angle between incident angle and scattered angle
Component B2: same as component B2 of mono-static RCS for human with RCS model 1



[FL1] Question 4.1.3-2 
If any new results are available, please provide your inputs on values/pattern of A*B1 and (mean, standard deviation) of B2 for human with RCS model 2



If any additional comments, please provide it in following table


Framework/values for vehicle with single scattering point
Summary on company views


AT&T:  For bistatic sensing, to model the RCS of a large vehicle with single scattering point
B2 is modelled using a log-normal distribution with standard deviation 6.1


[Moderator’s note] Better to check if more inputs are available. 
[FL1] Question 4.1.4-1 
If any new results are available, please provide your inputs on values/pattern of A*B1 and (mean, standard deviation) of B2 for vehicle with single scattering point


[FL1] Question 4.1.4-2 
If any new results are available, please provide your inputs on values/pattern of A*B1 and (mean, standard deviation) of B2 for vehicle with multiple scattering points



If any additional comments, please provide it in following table


Framework/values for AGV
Summary on company views



[Moderator’s note] Better to check if more inputs are available. 
[FL1] Question 4.1.5 
If any new results are available, please provide your inputs on values/pattern of A*B1 and (mean, standard deviation) of B2 for AGV



If any additional comments, please provide it in following table


[H] Monostatic RCS
Nokia: Table 5  3GPP specified parameters for mid-sized UAV for monostatic scenario

Values for UAV of large size
Summary on company views



[Moderator’s note] Better to check if more inputs are available. 

[FL1] Question 4.2.1 
If any new results are available, please provide your inputs on values/pattern of A*B1 and (mean, standard deviation) of B2 for UAV with large size



If any additional comments, please provide it in following table



[FL3] Proposal 4.2.1-1 
On the monostatic RCS of UAV of large size,
The values/pattern of component A*B1 are generated by the following parameters 

When  is in the range [0°,45° ] or [135°,180°], 
The standard deviation of component B2 is 2.50 dB


Framework/values for human with RCS mode 2
Summary on company views

Angular dependency
Horizontal: IDC, OPPO, LGE
Vertical: IDC, HW, DOCOMO
Not support: BUPT


QC
For model 1, for a child, support a component A which is 5 dBsm lower than the adult:
Component A: -6.37 dBsm
Component B1: 0 dB (already agreed in RAN1#118bis)
Component B2: 


[Moderator’s note] Better to check if more inputs are available. 

[FL1] Proposal 4.2.2-1 
On the monostatic RCS for human with RCS model 2
The monostatic RCS for a scattering point of the target is generated by
The values/pattern A*B1, i.e.,  is deterministic based on incident/scattered angles

Where,


FFS how many rows of the values/pattern A*B1 are defined for the target
Note: each row has a defined applicable range of  and 



[FL1] Proposal 4.2.2-1-rev1 
On the monostatic RCS for human with RCS model 2
The monostatic RCS for a scattering point of the target is generated by
The values/pattern A*B1, i.e.,  is deterministic based on incident/scattered angles

Where,


FFS how many rows of the values/pattern A*B1 are defined for the target
Note: each row has a defined applicable range of  and 
Note: whether the RCS is elevation angle dependent or dependent on both elevation and horizontal angles can be separately discussed


[Moderator’s note] Agreement in Tuesday online
Agreement
On the monostatic RCS for human with RCS model 2
The monostatic RCS for a scattering point of the target is generated by
The values/pattern A*B1, i.e.,  is deterministic based on incident/scattered angles

Where,


FFS how many rows of the values/pattern A*B1 are defined for the target
Note: each row has a defined applicable range of  and 
Note: whether the RCS is elevation angle dependent or dependent on both elevation and horizontal angles can be separately discussed


[FL1] Question 4.2.2-2 
If any new results are available, please provide your inputs on values/pattern of A*B1 and (mean, standard deviation) of B2 for Human with RCS model 2



If any additional comments, please provide it in following table


[FL3] Proposal 4.2.2-2 
On the monostatic RCS of human with RCS model 2,
The values/pattern of component A*B1 are generated by the following parameters 

The standard deviation of component B2 is [?] dB



Values for AGV
Summary on company views


Nokia: Table 7  3GPP specified parameters for quadruped robot for monostatic scenario


[Moderator’s note] Better to check if more inputs are available. 

[FL1] Question 4.2.3 
If any new results are available, please provide your inputs on values/pattern of A*B1 and (mean, standard deviation) of B2 for AGV



If any additional comments, please provide it in following table


[FL3] Proposal 4.2.3-1 
On the monostatic RCS of AGV with single scattering point,
The values/pattern of component A*B1 are generated by the following parameters 

When  is in the range [0°,30° ), 
The standard deviation of component B2 is 2.51 dB

[H] Value of component A for bistatic and monostatic sensing modes

Summary on company views

E//: For mono-static sensing mode, bi-static RCS modelling is needed for indirect paths
E//: For a type of target, mono-static RCS and bi-static RCS constitute the whole RCS to derive value A, B1 and B2. Such A is used to calculate power scaling factor

Component A
different values of component A respectively for monostatic RCS and bistatic RCS of same target
same value of component A for monostatic RCS and bistatic RCS of same target: Nokia, LGE, vivo, BUPT, ZTE, Ericsson, Sony, Tejas


[Moderator’s note] Based on the compromise agreement in last meeting, we need to decide a value for component A for a target. Multiple companies prefer to define same value A for monostatic/bistatic RCS for simplicity
[FL2] Proposal 4.3-1 
The same value of the component A is applied to the monostatic RCS and the bistatic RCS of a target
Exact value of component A is to be discussed per target


Angular correlation of RCS
Summary on company views

Whether to model correlation of RCS of a scattering point in adjacent incident/scattered angles?
Yes (5): Lenovo, LGE, E//, NIST, Sony
Use a correlation distance: Lenovo
Sum of sinusoids: E//
No (11): ZTE, HW, Nokia, vivo, QC, BUPT, CATT, SS(deprioritized), MTK, Xiaomi, Apple(low priority)

Spatial-temporal consistency of RCS : E//, NIST, Lenovo
E//: Model the stochastic B2 with C random scattering centres as 
NIST:  generated by convolving i.i.d. Lognormal random values with the ACF model,  where .
Sony: 


E//: B2 must be continuous over the incidence and scattering angles
E//: Discontinuous behavior leads to non-physical artifacts in the channel, including very high Doppler frequencies and spurious out-of-band artifacts



LGE: RCS as a random time-domain process:
Sony: Consider correlation angle  [º] on B1

NIST: We observe notable correlations across multiple angle lags , indicating that the small-scale RCS (B2) exhibits some spatial (temporal) correlation

Figure 3-7: Small-Scale RCS (B2) autocorrelation function as a function of angle lag.
Sony
Table 1: Summary of RCS simulation results of UAV model option 2 


[Moderator’s note] The existing validation results show that the RCS values fluctuate a lot with the change of incident/scattered angles. However, the RCS value of close/adjacent incident/scattered angles can still have some correlations as discussed in some contributions. On the other hand, some companies comment that the angle dependent pattern of B1 (or A*B1) is already a means to model correlation of adjacent incident/scattered angles. 
[FL1] Question 4.4-1
Companies are encouraged to comment on whether/how to model correlation of RCS of a scattering point in adjacent incident/scattered angles?


[H] XPR to generate polarization matrix
Summary on company views

Xiaomi, Apple, ZTE, BUPT, QC, Sony: The proposed XPR distribution/value are summarized in following table

CMCC: There’s a clear difference between the CPM distributions of monostatic and bistatic modes.
E//: 
Support any orientation of target by defining  in a Local Coordinate System (LCS) and reusing the procedure for the support of arbitrary orientation of BS and UE in section 7.1 of 38.901
CPMsp must be specified in a local coordinate system, in which the z-axis is parallel to the z-axis in the global coordinate system, .
If the change of orientation leads to a change of z axis, such as a vehicle driving on/off a slope, rotation procedure is needed because the cross-polarization matrix is no longer diagonally dominant.

Nokia: Reuse the TR 38.901 log-normal distribution parameters as baseline: 
 for LOS of Umi, and  for LOS of Uma


[Moderator’s note] Based on the agreement from last meeting, one open issue is to collect the values of mean and standard deviation for XPR. Please provide your values if available. 

[FL1] Question 4.5-1 
If any new results are available, please provide your inputs on the mean and standard deviation of XPR to generate the polarization matrix of a direct/indirect path of a scattering point of UAV, human, vehicle, AGV, and other targets 



[FL1] Proposal 4.5-1 
The following mean and standard deviation values of XPR of targets are agreed
UAV: (13.75, 7.07) dB
Human: (19.81, 4.25) dB
Vehicle: (21.12, 6.88) dB


[Moderator’s note] Agreement in Tuesday online 
Agreement
The following mean and standard deviation values of XPR of targets are agreed for monostatic sensing and bistatic sensing as follows:
UAV: (13.75, 7.07) dB
Human: (19.81, 4.25) dB
Vehicle: (21.12, 6.88) dB

Angular correlation of polarization matrix
Summary on company views

Whether to model correlation of polarization matrix (XPR, initial random phase) of a scattering point in adjacent incident/scattered angles?
Yes: Ericsson, CATT (impact to Doppler), IDC
NO: HW, Nokia, LGE, vivo, BUPT, ZTE, QC, Xiaomi

IDC: Initial random phase and XPR of CPM_sp is link-correlated for spatially consistent mobility odelling of the same target only
CATT
The base station rotation procedure for CPM of target is not necessary because the XPR and random phase are generated statistically.


[Moderator’s note] Unlike the discussion on correction of RCS B2, there is no validation result available for XPR. More inputs from companies are necessary. 
[FL1] Question 4.6-1
Companies are encouraged to comment on whether/how to model correlation of XPR/initial random phase of a scattering point in adjacent incident/scattered angles?


RCS for other targets/EO type-1
Summary on company views

E//: For outdoor human scenario, the type of sensing targets which may be evaluated in future study is not limited to pedestrian and can be cyclists, E-Scooter, and motorcyclists.
E//: For the bistatic RCS of birds, use an isotropic model with A between -40 to -20 dBsm for a single bird, and A = 0 dBsm for a migrant flock.

Ericsson: Use the following bistatic RCS model for a single tree: A*B1 with a constant level of 10 dBm2 and a single lobe in the forward direction with A*B1 increasing to 23 dBm2. The B2 standard deviation is approximately 3 dB.

Nokia: Table 6  3GPP specified parameters for robotic arm for monostatic scenario

LGE: Model the monostatic RCS of animal as the product of the angular independent component A = 1.5 dBsm, the component B1=1 and the component B2 having the standard deviation σ = 3.94 dB.

[Moderator’s note] For any other targets, e.g., object creating hazard on road, or certain EO type-1. If the measurement data are available and agreeable, we would try to complete them in the study item. 
[FL1] Question 4.7-1 
Please provide your inputs on values/pattern of A*B1 and (mean, standard deviation) of B2 for human with RCS model 2



If any additional comments, please provide it in following table


Collection on the setup for RCS measurement from companies 

[Moderator’s note] Based the email discussion [Post-120-ISAC-01] and confirmation by Chair, we would create a document to collect details on the setup for RCS measurement/simulation (i.e. vehicle size, frequency, distance, etc). The file include separate sheets for different target types. Please consider adding your information for measurement/odelling. 
/Inbox/drafts/9.7(FS_Sensing_NR)/9.7.2 Channel Modelling/R1-250xxxx Setup on RCS measurement_v000.xlsx


If any additional comments, please provide it in following table


ISAC channel model
ZTE: Dual mobility model in TR 38.901 is used to model the Doppler frequency in background channel of UT mono-static, with the velocity of the reference point setting same as velocity of Tx.
IDC: An unintended target is a blockage factor in the target channel and further study whether Blockage model A or Blockage model B should be implemented
[H] Reference TRs
Summary on company views

Ericsson
It needs evaluation whether BS-aerial UE in 36.777 can be reused for terrestrial UE-UAV link and terrestrial UE-aerial UE channel, especially for indoor Ues.
It needs evaluation whether BS-aerial UE in 36.777 can be reused for aerial UE-UAV link, because it requires changing BS height from at most 35m to up to 300m (aerial UE height).
Both aerial UE and UAV can be of any same or different heights in the large range of [1.5m, 300m]. It needs consideration whether/how LOS probability, pathloss model, shadow fading parameters for different UAV heights in 36.777 can be extended to support combinations of two heights of aerial UE and UAV.
QC
For TRP/UE to aerial UE for FR2, support reusing the channel model of FR1. 
For aerial-UE to aerial-UE, support reusing the D2D channel model from 36.843 A.2.1.2 is used.
IDC
Reuse UMi-AV, UMa-AV and RMa-AV scenarios of TRP to aerial UE channel model defined in TR 36.777 for channel between a normal UE and an aerial UE as a starting point
Capture the same TRs as case 7 for case 9 to model the channel between two aerial Ues as a starting point.
BUPT
For the UAV-UT case, we recommend modifying the BS height to 1.5 m as per TR 38.858, while ensuring that the angular spread values (ASA and ASD for UT) at the UT side align with those in the corresponding UMi, UMa, and RMa scenarios in TR 38.901.
For UAV TR selection in FR2, we propose retaining the LOS probability and path loss calculations from TR 36.777, while adopting Alternative 3 for fast fading odelling (K=15, with all other parameters following TR 38.901).
CATT
TRP-UAV channel defined in TR 36.777 is used to model the channel between UAV and cellular UE.
Channel model between a UE and a RSU and between two UE-type RSUs reuse the V2V channel model with antenna height at RSU changed to 5m, as defined in TR 37.885.
Channel model between a TRP and a RSU should reuse the B2R link modelling in TR 37.885.

[Moderator’s note] We agreed on the reference TRs for the links between TRP-TRP, TRP-UE and normal UE-normal UE. A basic/rough principle for such agreement is to have 38.901-like option. Such a rule can be extended to other kinds of links. In the following Table x for reference TRs, only one option is kept for each pair of link for each scenario. Please check if it is agreeable. 

Table x: Reference TRs
The related sections in the following existing TRs are used as starting point to generate a channel between any two nodes from TRP, normal UE, vehicle UE and aerial UE. 


[FL1] Proposal 5.1-1 
In order to generate Tx-target link, target-Rx link and the background channel, The above table on reference TRs (excluding the already agreed part) is adopted for the mapping between reference TRs and a pair of nodes (STX, SRX, target) 



[FL1] Proposal 5.1-1-rev1 
In order to generate Tx-target link, target-Rx link and the background channel, The above table on reference TRs (excluding the already agreed part) is adopted for the mapping between reference TRs and a pair of nodes (STX, SRX, target) 
FFS RSU type UE


[Moderator’s note] Agreement from Tuesday online
Agreement
In order to generate Tx-target link, target-Rx link and the background channel, the above table on reference TRs (excluding the already agreed part) is adopted for the mapping between reference TRs and a pair of nodes (STX, SRX, target) 
Note: continue discussion for updating the table with RSU type UE
FFS: the generation of background channel based on reference TRs is subject to the addition of low-energy clusters



[Moderator’s note] Let’s check the following proposals on handling RSU type UE

[FL3] Proposal 5.1-2 
In order to generate Tx-target link, target-Rx link and the background channel between a RSU-type UE and another node (TRP, pedestrian UE, vehicle UE, RSU-type UE), the following reference TRs are adopted






[FL3] Question 5.1-3 
For Case 7 “normal UE + aerial UE”, please provide your input regarding how to solve the issue on LOS probability and other FFSs



[FL3] Proposal 5.1-3 
The LOS probability between an aerial UE and a normal UE is the following:

With 





,   
with parameter values 

For aerial UE heights similar to the corresponding macro BS height (25 m in UMa, 35 m in RMa), use the UMa or RMa model in TR 38.901 with the BS representing the aerial UE. 
For aerial UE heights that are higher than the corresponding macro BS height (25 m in UMa, 35 m in RMa), use the UMa or RMa model in TR 38.901 with the BS representing the aerial UE. 

[H] Parameter values to generated background channel for monostatic

Summary on company views

Nrp = 3: ZTE Corporation, Sanechips, OPPO, BUPT, BJTU, CAICT, Xiaomi, Huawei
Nrp = 1: SS, Apple

ZTE, et al.: Confirm the previous working assumption on background channel for mono-static sensing with the following details:
reference points are dropped for one Tx, based on the Gamma distribution for distance and height of reference point.
The LOS AOD between Tx and the first reference point is generated based on uniform distribution , and the gap of LOS AOD between the Tx and different reference points keeps as .
The background channel is generated based on the channel generated as in existing TR between the real Tx and the reference point in NLOS condition.
The antenna field pattern and array orientation of reference point are set same as Tx. 
Arrival angles for both azimuth and elevation  and  are set equal to departure angles, and coupled with the corresponding departure angles one by one.
The mono-static background channel for the Tx would be sum of channels of the links between the Tx and all related reference points, which is

ZTE et al. 
Proposal 2: For background channel of mono-static sensing, the distance between Tx and the reference point, and the height of the reference point follow parameterized Gamma distribution  with offset , and the related parameters in scenarios of UMa, UMi, RMa, Urban grid, Indoor-office,  and highway are given by:

Huawei: 
Proposal 12: The generation and parameters for the background channel for mono-static sensing can be modelled as:
Step1：deploy the reference points as:




The 3D coordinates of the reference points are:

Step 2: generate the clusters following the TR 38.901 generation steps under NLOS condition with modification as
number of clusters = 8.
SF = 2.5
the absolute delay for each cluster generated as

Step 3: Combine the channels of each BS-RP link.

ZTE, et al. 
Highway: The distribution of reference points of RMa is reused for Highway scenario.
Urban grid: The distribution of reference points of UMa is reused for urban grid scenario.
CATT
For the Mono-static target channel modelling, the determination of delay, angle, K factor and polarization matrix for Tx-target link and target-Rx link should follow the following rules:
Same K factor should be used for two separate links.
LOS AOA and LOS ZOA of target-Rx link should be the same as LOS AOD and LOS ZOD of Tx-target link.
LOS AOD and LOS ZOD of target-Rx link should be the same as LOS AOA and LOS ZOA of Tx-target link.
Delay spread, angle spread and polarization for the two separate links should be generated independently.
The ASA and ZSA of target-Rx link should obey the same statistical distribution characteristics of ASD and ZSD of Tx-target link, respectively.
The ASD and ZSD of target-Rx link should obey the same statistical distribution characteristics of ASA and ZSA of Tx-target link, respectively.
E//: Revert the working assumption from RAN1#120 and continue study Option 2 and Option 3 in the RAN1#118 agreement
Nokia: clutter map is proposed for the background channel


[Moderator’s note] Thanks for all companies working on the parameter values based on the working assumption from last meeting. A joint contribution is available which summarizes data for each sensing scenario. Additionally, a set of values are proposed by Huawei which seems well aligned with the joint tdoc, too. 

[FL1] Proposal 5.2-1
Confirm the previous working assumption on background channel for mono-static sensing with the following details:
 reference points are dropped for one Tx, based on the Gamma distribution for distance and height of reference point.
The LOS AOD between Tx and the first reference point is generated based on uniform distribution , and the gap of LOS AOD between the Tx and different reference points keeps as .
The background channel is generated based on the channel generated as in existing TR between the real Tx and the reference point assuming NLOS condition.
The antenna field pattern and array orientation of reference point are set same as Tx. 
Arrival angles for both azimuth and elevation  and  are set equal to departure angles
The absolute delay model  as agreed for bistatic sensing for the same sensing scenario applies. 
The mono-static background channel for the Tx would be sum of channels of the links between the Tx and all related reference points, which is



[FL1] Proposal 5.2-1-rev1
Confirm the previous working assumption on background channel for mono-static sensing with the following details:
 reference points are dropped for one Tx, based on the Gamma distribution for distance and height of reference point.
The LOS AOD between Tx and the first reference point is generated based on uniform distribution , and the gap of LOS AOD between the Tx and different reference points keeps as .
The background channel is generated based on the channel generated as in existing TR between the real Tx and the reference point assuming NLOS condition.
The antenna field pattern and array orientation of reference point are set same as Tx. 
Arrival angles for both azimuth and elevation  and  are set equal to departure angles
The absolute delay model d3D and  as agreed for bistatic sensing for the same sensing scenario applies. 
The mono-static background channel for the Tx would be sum of channels of the links between the Tx and all related reference points, which is

FFS: Doppler frequency in background channel for monostatic sensing
FFS: whether to add additional very low power clusters
FFS: any update to parameters e.g. angular distribution and delay spread


[Moderator’s note] Further revised based on online discussion and offline 

[FL2] Proposal 5.2-1-rev2
On background channel for mono-static sensing, the following details are provided:
 reference points are dropped for one Tx, based on the Gamma distribution for distance and height of reference point.
The LOS AOD between Tx and the first reference point, which is denoted as AOD1, is generated based on uniform distribution .
The LOS AOD between Tx and the second reference point is AOD1 + 
The LOS AOD between Tx and the third reference point is AOD1 + 
The background channel is generated based on the channel generated as in existing TR between the real Tx and the reference point assuming NLOS condition.
The antenna field pattern and array orientation of reference point are set same as Tx. 
Arrival angles for both azimuth and elevation  and  are set equal to departure angles
The absolute delay model [d3D and]  as agreed for bistatic sensing for the same sensing scenario applies. 
The mono-static background channel for the Tx would be sum of channels of the links between the Tx and all related reference points, which is

FFS: Doppler frequency in background channel for monostatic sensing
FFS: whether/howto add additional very low power clusters
FFS: any update to parameters e.g. angular distribution and delay spread


[Moderator’s note] revised in Wed offline session

[FL3] Proposal 5.2-1-rev3
On background channel for mono-static sensing, the following details are provided:
 reference points are dropped for one Tx, based on the Gamma distribution for distance and height of reference point.
The LOS AOD between Tx and the first reference point, which is denoted as AOD1, is generated based on uniform distribution .
The LOS AOD between Tx and the second reference point is AOD1 + 
The LOS AOD between Tx and the third reference point is AOD1 + 
The background channel is generated based on the channel generated as in existing TR between the real Tx and the reference point assuming NLOS condition.
The antenna field pattern and array orientation of reference point are set same as Tx. 
Arrival angles for both azimuth and elevation  and  are set equal to departure angles
The absolute delay model d3D and  as agreed for bistatic sensing for the same sensing scenario applies. 
Option 1: A scaling factor d_s is applied to d3D. d_s is uniformly distributed with [0, 1] 
Option 2: A scaling factor d_s is applied to d3D. d_s = d3D-c1
The mono-static background channel for the Tx would be sum of channels of the links between the Tx and all related reference points, which is

FFS: Doppler frequency in background channel for monostatic sensing
FFS: whether/howto add additional very low power clusters
FFS: any update to parameters e.g. angular distribution and delay spread
The rays in a stochastic cluster with ZOA at BS less than D degree are dropped [with probability p, p=1] 
D=[90] for RMa, 
D=[60] for UMa



Package proposal
[FL3] Proposal 5.2-1-rev3
On background channel for mono-static sensing, the following details are provided:
 reference points are dropped for one Tx, based on the Gamma distribution for distance and height of reference point.
The LOS AOD between Tx and the first reference point, which is denoted as AOD1, is generated based on uniform distribution .
The LOS AOD between Tx and the second reference point is AOD1 + 
The LOS AOD between Tx and the third reference point is AOD1 + 
The background channel is generated based on the channel generated as in existing TR between the real Tx and the reference point assuming NLOS condition.
The antenna field pattern and array orientation of reference point are set same as Tx. 
Arrival angles for both azimuth and elevation  and  are set equal to departure angles
The absolute delay model d3D and  as agreed for bistatic sensing for the same sensing scenario applies. 
Option 0: no scaling factor is applied to d3D
Option 1: A scaling factor d_s is applied to d3D. d_s is uniformly distributed with [0, 1] 
Option 2: A scaling factor d_s is applied to d3D. d_s = The absolute delay is d3D-c1+
Option 3: A scaling factor d_s is applied to d3D. d_s is within range [0, 1]. FFS value of d_s 
The mono-static background channel for the Tx would be sum of channels of the links between the Tx and all related reference points, which is

FFS: Doppler frequency in background channel for monostatic sensing
The rays in a stochastic cluster with ZOA at BS less than D degree are dropped [with probability p, p=1] 
D=[90] for RMa, 
D=[60] for UMa
Note: this threshold for ZOA is not applicable to other sensing scenarios


[FL3] Proposal 5.4-3 
To generate the background channel, the power threshold (-25 dB) for removing clusters in step 6 in section 7.5, TR 38.901 is reused.


[FL3] Proposal 5.4-4-rev1 
The ISAC background channel can be generated between a sensing Tx and a sensing Rx or RP (relevant for monostatic case) via the following steps:
Step 1: generate a first set of clusters/rays according to TR 38.901(or other related TRs)
Step 2: generate a second set of NLOS clusters/rays according to TR 38.901 (or other related TRs), where the power of the second set of clusters/rays should be scaled down such that


(,   are the power of the n-th cluster from the first and second set, respectively).
Where, N is the number of clusters, M is the number of rays within each cluster, value of G relates to power
Option 1: N=360, M=1, G=0dB, with uniform delay and angle (only for mono-static case)
Supported by: Nokia
Option 2: N=[360 or 60], M=1, G = -25dB, no further change from 38.901, 36.777, 38.858 (i.e., utilizing the same DS, ASA, ASD, ZSA, ZSD, ,  as used for the first step)
Supported by: Xiaomi, ZTE, Lenovo, MTK, Qc, CMCC, IDCC, 
Note: the step 2 is an additional modeling component
Note: applicability of low-power clusters to scenarios is part of evaluation phase


[Moderator’s note] revised in Thursday offline session

[H]Package proposal -rev1
[FL3] Proposal 5.2-1-rev3
On background channel for mono-static sensing, the following details are provided:
 reference points are dropped for one Tx, based on the Gamma distribution for distance and height of reference point.
The LOS AOD between Tx and the first reference point, which is denoted as AOD1, is generated based on uniform distribution .
The LOS AOD between Tx and the second reference point is AOD1 + 
The LOS AOD between Tx and the third reference point is AOD1 + 
The background channel is generated based on the channel generated as in existing TR between the real Tx and the reference point assuming NLOS condition.
The antenna field pattern and array orientation of reference point are set same as Tx. 
Arrival angles for both azimuth and elevation  and  are set equal to departure angles
The absolute delay model d3D and  as agreed for bistatic sensing for the same sensing scenario applies. 
Option 0: no scaling factor is applied to d3D
Supported by: Apple, SS, ZTE, OPPO, HW, MTK, CATT, SPRD, LGE, Xiaomi, 
Option 1: An offset is applied to d3D, i.e., d3D-c1
Supported by: Ericsson, 
Option 2: A scaling factor d_s is mulitplexed to d3D, i.e., d3D*d_s. d_s is a value within range [0, 1]. 
Supported by: Ericsson, 
Note: The adjustment of absolute delay doesn’t impact the generation of NLOS clusters between the Tx and each reference point
The mono-static background channel for the Tx would be sum of channels of the links between the Tx and all related reference points, which is

FFS: Doppler frequency in background channel for monostatic sensing
The rays in a stochastic cluster with ZOA at BS less than D degree are dropped [with probability p, p=1] 
D=[90] for RMa, 
D=[60] for UMa
Note: this threshold for ZOA is not applicable to other sensing scenarios


[FL3] Proposal 5.4-3 
To generate the background channel, the power threshold (-25 dB) for removing clusters in step 6 in section 7.5, TR 38.901 is reused.


[FL3] Proposal 5.4-4-rev1 
The ISAC background channel can be generated between a sensing Tx and a sensing Rx or RP (relevant for monostatic case) via the following steps:
Step 1: generate a first set of clusters/rays according to TR 38.901(or other related TRs)
Step 2: generate a second set of NLOS clusters/rays according to TR 38.901 (or other related TRs), where the power of the second set of clusters/rays should be scaled down such that


(,   are the power of the n-th cluster from the first and second set, respectively).
Where, N is the number of clusters, M is the number of rays within each cluster, value of G relates to power
Option 1: N=360, M=1, G=0dB, with uniform delay and angle (only for mono-static case)
Supported by: Nokia
Option 2: N=360, M=1, G = -25dB, no further change from 38.901, 36.777, 38.858 (i.e., utilizing the same DS, ASA, ASD, ZSA, ZSD, ,  as used for the first step)
Supported by: Xiaomi, ZTE, Lenovo, MTK, Qc, CMCC, IDCC, 
The step 2 is an additional modeling component
Note: applicability of low-power clusters to scenarios is part of evaluation phase
Supported by: Xiaomi, OPPO, LGE, QC, ZTE, SS, Huawei, 
FFS: in which communication scenario(s) low-power clusters need to be included
Supported by: Lenovo, Ericsson, 
No sub-bullet on note or FFS: 
Supported: CATT, MTK, ZTE, SS, LGE, Sony, Xiaomi, OPPO, Huawei, 

Vivo has concern on the package proposal




[Moderator’s note] As suggested by the joint contribution, the fitted data for Uma/Rma can be extended to Urban grid and highway. Some further observation from moderator are
For highway, it is derived by Rma for FR1, but is Uma for FR2
For HST, it is derived by Rma
Therefore, the moderator extends/revises the proposal from the joint contribution. Please check if the following proposal is agreeable. 

[FL1] Proposal 5.2-2
The values of the parameters to generated background channel for TRP monostatic sensing for each sensing scenario are provided in the following table 




[FL2 Proposal 5.2-2-rev2
The values of the parameters to generated background channel for TRP monostatic and UE monostatic sensing for each sensing scenario are provided in the following table 
FFS parameter values for other scenarios


[Moderator’s note] Revised in Wed offline session

[FL3] Proposal 5.2-2-rev3 for working assumption
The values of the parameters to generated background channel for TRP monostatic and UE monostatic sensing for each sensing scenario are provided in the following table 
FFS parameter values for other scenarios
An email discussion checking the values after April meeting are preferred, including newly agreed parameters





[H][FL3] Proposal 5.2-2-rev4 for working assumption
The values of the parameters to generated background channel for TRP monostatic and UE monostatic sensing for each sensing scenario are provided in the following table 
FFS parameter values for other scenarios
An email discussion/approval checking the values after April meeting is preferred, including validation for newly agreed parameters
The email discussion includes all scenarios, TRP monostatic and UE monostatic



[Moderator’s note] We already have agreement that large scale parameters are same for the Tx-target and target-Rx links for monostatic sensing. A remaining issue is the small scale parameters as discussed by CATT. For reciprocity, should we assume all small scale parameters are same for the Tx-target and target-Rx links?

[FL1] Proposal 5.2-3
The small scale parameters used to generate the Tx-target link are respectively same as that of the target-Rx link. 



[FL1] Proposal 5.2-3-rev1
The small scale parameters used to generate the Tx-target link are respectively same as that of the target-Rx link for monostatic sensing. 


[Moderator’s note] Agreement after Tuesday online
Agreement
To generate the parameters (in the steps before concatenation), the large-scale parameters and the small-scale parameters used to generate the Tx-target link are respectively the same as that of the target-Rx link for monostatic sensing, where departure angle on one link and arrival angle on the other link are reciprocal.
FFS: whether this applies to initial phase


[H] Polarization matrix normalization
Summary on company views

Whether/how normalization on the polarization of a direct/indirect path, i.e., CPMtx,sp,rx= CPMsp,rx . CPMsp . CPMtx,sp is supported? 
No: LG, Nokia, CAICT
Yes: ZTE, vivo, Samsung, Qualcomm, OPPO, HW, Apple, BUPT
: ZTE
: HW
diagonal-term normalization: QC, Apple
: vivo
: BUPT

Vivo: RAN1 determines whether the power normalization of CPM is necessary after CPM concatenation depends on the value of XPR for CPM of target.
The magnitude of the diagonal elements of each component CPMsp,rx , CPMsp , CPMtx,sp  should be set to 1: Apple

[Moderator’s note] The majority view is to have normalization. ZTE has results comparing different options for normalization and the conclusion is using absolute value is the best. Please check if you are OK with the following proposal. 

[FL1] Proposal 5.3-1 
Normalization on the product of three polarization matrixes of a direct/indirect path, i.e., CPMtx,sp,rx= CPMsp,rx . CPMsp . CPMtx,sp is supported
The scaling factor is 



[FL1] Proposal 5.3-1-rev1 
Normalization on the product of three polarization matrixes of a direct/indirect path, i.e., CPMtx,sp,rx= CPMsp,rx . CPMsp . CPMtx,sp is supported
The scaling factor is 


[Moderator’s note] Agreement in Tuesday online
Agreement
Normalization on the product of three polarization matrixes of a direct/indirect path generated by stochastic cluster, i.e., CPMtx,sp,rx= CPMsp,rx . CPMsp . CPMtx,sp is supported
The scaling factor is 


[H] Power threshold 

Summary on company views

Power threshold for path dropping after concatenation
-40dB: HW, Nokia, CATT, CMCC, OPPO, Xiaomi (-45 first), Apple, Spreadtrum
-25dB: LGE
Inf: QC, IDC

Removing a cluster from background channel referring to the maximum path power in target channel: LGE, Apple
IDC: Do not adopt path dropping after concatenation

Power normalization of target channel after path dropping
Not supported: HW, Xiaomi, Nokia, LGE, CMCC, Panasonic, Apple
Supported: SS, Tiami

Power threshold for cluster dropping for background channel 
The power threshold for cluster dropping in background channel can be discussed together with possible introduction of very low power clusters. 
Option 1: threshold = -25dB, no additional very low power clusters
LG(2nd), CATT, Xiaomi, Apple
Option 2: threshold < -25dB, no additional very low power clusters
HW (-40), Tejas(-Inf)
Option 3: threshold = -25dB, introducing additional very low power clusters
Nokia, ZTE, Lenovo
Option 4: threshold < -25dB, introducing additional very low power clusters
Nokia, ZTE, Lenovo, QC(-Inf)
Option 5: threshold = -25dB, removing a cluster from background channel referring to the maximum path power in target channel 
LG(1st), MTK

Add additional very low power clusters: QC, Lenovo, Tiami
QC, Tiami: Introduce a set of low-power clusters in the background channel which have a power that is in the order of the ISAC target channel’ sensing clusters
Lenovo: clutter with an energy of at least 7 dB [or a required SSNR value corresponding to a sensing task] below the energy of the target channel shall be modelled in the ISAC background/environment channel.
For the generation of the low-energy cluster/rays, [] = [40-240, 1], would be sufficient to obtain required dynamic range of the background channel for the bistatic sensing scenarios.

Huawei: The reference power for removing cluster can follow the TR38.901 without any other updates

Lenovo
For the generation of the low-energy cluster/rays, [] = [180-240, 1], would be sufficient to obtain required dynamic range of the background channel for both bistatic and monostatic sensing scenarios.
The stochastic clutter associated with an ISAC background channel can be odellin via the following steps:

[Moderator’s note] Based on the contributions, -40dB as the power threshold is agreeable

[FL2] Proposal 5.4-1 
Power threshold for path dropping after concatenation is -40dB for target channel


[FL3] Proposal 5.4-1-rev1 
Power threshold for path dropping after concatenation is -25dB for target channel




[Moderator’s note] There is clear common view that power normalization after path dropping is not necessary

[FL1] Proposal 5.4-2 
Power normalization of target channel after path dropping of the target channel is not supported


Agreement
Power normalization of target channel after path dropping of the target channel is not supported.


[Moderator’s note] The most straightforward way is to reuse the threshold -25dB in cluster dropping, which also maintains backward compatibility with communication. However, considering the analysis that the path in background channel may be much higher than a path in the target channel, a simple way to mitigate it is to lower the threshold for cluster dropping in Step 6 generating the background channel. Not dropping a cluster <-25dB will have neglectable impacts to communication (the reason why such cluster is dropped in exiting TR). Therefore, the moderator propose that we reduce the power threshold, e.g. Huawei suggests to use -40dB. 

[FL2] Proposal 5.4-3 
To generate the background channel, the power threshold for removing clusters in step 6 in section 7.5, TR 38.901 is -40 dB 


[FL3] Proposal 5.4-3 
To generate the background channel, the power threshold for removing clusters in step 6 in section 7.5, TR 38.901 is reused


[Moderator’s note] Regarding the FFS point of additional very low power clusters, please proponent company provide your solution. It is good if the proponent can converge to a single option, otherwise it is hard to move forward. 

[FL1] Question 5.4-4 
Whether/how to model some lower power NLOS clusters in background channel beyond those generated by existing section 7.5, TR 38.901?



[FL2] Proposal 5.4-4 
The ISAC background channel can be generated between a sensing Tx and a sensing Rx or RP (relevant for monostatic case) via the following steps:
Step 1: generate a first set of clusters/rays according to TR 38.901
Step 2: generate a second set of NLOS clusters/rays according to TR 38.901, where the power of the second set of clusters/rays should be scaled down such that


(,   are the power of the n-th cluster from the first and second set, respectively).
FFS any modification from 38.901 for the second set including the number of clusters N, and the number of rays within each cluster M, value of G, the large scale statistics (for generation of the second set of clusters)
Example 0. G = -25dB
Example 1 N=360, M=1, G=0dB, with uniform delay and angle (for mono-static case)
Example 2 N=120, M=1, G = -25dB, no further change from 38.901
Note: the step 2 is an additional modeling component


[Moderator’s note] Revised in Wed offline session. Adding 36.777, 38.858
[FL3] Proposal 5.4-4-rev1 
The ISAC background channel can be generated between a sensing Tx and a sensing Rx or RP (relevant for monostatic case) via the following steps:
Step 1: generate a first set of clusters/rays according to TR 38.901(or other related TRs)
Step 2: generate a second set of NLOS clusters/rays according to TR 38.901 (or other related TRs), where the power of the second set of clusters/rays should be scaled down such that


(,   are the power of the n-th cluster from the first and second set, respectively).
Where, N is the number of clusters, M is the number of rays within each cluster, value of G relates to power
Option 1: N=360, M=1, G=0dB, with uniform delay and angle (only for mono-static case)
Supported by: Nokia
Option 2: N=60, M=1, G = -25dB, no further change from 38.901, 36.777, 38.858 (i.e., utilizing the same DS, ASA, ASD, ZSA, ZSD, ,  as used for the first step)
Supported by: Xiaomi, ZTE, Lenovo, MTK, Qc, CMCC, IDCC, 
Note: the step 2 is an additional modeling component


[H] Impact of height of target on LOS probability or pathloss
Summary on company views

Breaking point distance
HW: When the path loss model of Umi, Uma and Rma scenario of TR38.901 is used for the target channel, only the  is applied in the target channel irrespective of the breakpoint distance.

[Moderator’s note] In general, the scattering point location for the target (human, vehicle, …) may be lower than the commonly used UT height, e.g., 1.5m. It mainly impacts LOS probability determination and pathloss calculation. A simple solution is to extend the application range of the formulas in the current TR. However, as discussed by several companies, some issues are found, hence some solutions are proposed. 

[FL3] Proposal 5.5-1 
For sensing scenario UMi, UMa, RMa, UMi-AV, UMa-AV and RMa-AV, the height of target is used to calculate the LOS probability and pathloss, regardless of the lower bound in the existing TRs that are referred to generate ISAC channel. 



[Moderator’s note] The possible issues caused by extending application range of hUT includes 1) low/negative distance of breaking point for Umi/Uma/Rma; 2) reduced LOS probability. Please provide your views on the favorite option. 

[FL1] Question 5.5-2 
Please provide your views/solutions on the following issues
Issue 1: Negative dBP result in using the large pathloss  when hUT is reduced to be less than 1m
Issue 2: LOS probability is reduced a lot for InF scenario when hUT is reduced



[FL3] Proposal 5.5-2 
In sensing scenario UMi, UMa, RMa, UMi-AV, UMa-AV and RMa-AV, the minimum d_BP is 10m. 


What is the proposal on the height of scattering point of a human?
Option 1: human height
Same RCS defined for human applies
Option 2: geometry center of human

[FL3] Proposal 5.5-2 for pathloss
In sensing scenario UMi, UMa, RMa, if the height of a scattering point of target is less than 1.5m
Option 1: the minimum d_BP is 10m. 
Option 2: the minimum d_BP is 0m. 
Option 3: hE = 0.25m
Option 4: use  in Table 7.4.1-1: Pathloss models in TR 38.901

[FL3] Proposal 5.5-3 for LOS probability
In sensing scenario InF, if the height of a scattering point of target is less than 1.5m
Option 1: hE = 0.25m
Option 2: hUT=max(h_scattering point, 1.5m)
Option 3: not considered as an issue


[FL3] Proposal 5.5-4
The height of scattering point of a human is the geometry center of the human

[FL3] Proposal 5.5-2-rev1
In sensing scenario UMi, UMa, RMa, if the height of a scattering point of target is less than 1.5m, for pathloss calculation, 
Option 1: the minimum d_BP is 10m. 
Nokia 
Option 2: the minimum d_BP is 0m. 
Ericsson, vivo
Option 4: use  in Table 7.4.1-1: Pathloss models in TR 38.901
HW, LGE, CATT, Samsung, ZTE, Xiaomi, OPPO, 

[FL3] Proposal 5.5-3 for conclusion
There is offline consensus that no special handling on LOS probability is necessary for InF due to the height of scattering point of human. 


Power normalization between target channel and background channel

Summary on company views

Alt 1: Power normalization on both target channel and background channel
Lenovo, Apple, Nokia, CATT, LGE, OPPO, QC, CT, Spreadtrum
Alt 2: Only the power of the background channel is scaled down to make total power normalized
EURECOM, ZTE, IDC, OPPO
Alt 3: the target channel of a target will replace one cluster in the background channel
BUPT (indoor/outdoor scenarios), Panasonic

OPPO: The power normalization in combining the target channel(s) and background channel is formulated as a linear programming problem, solved as following. 
The power normalization coefficient for the background channel is 
The power normalization coefficient for a target channel is 
QC: Support the following power normalization between the target and the background channel:
, where  is such that 
BUPT: When combining the target and background channels, different options can be selected based on the scenario category or blockage situation:
Method 1: In UAV scenarios, directly superimpose the target and background channels (Option 1). In indoor/outdoor scenarios, remove background cluster c that are closest to the target in the angular domain and replace them with the target channel (Option 2-Alt 3). 
Method 2：Remove background clusters that are blocked by the target in the angular domain. The possibility of blockage is high in indoor and outdoor scenarios (Option 2-Alt 3) but relatively low in UAV scenarios (Option 1).

Whether/how to specify a condition to select Option 1 or 2
Yes: BUPT
No: CATT

[Moderator’s note] Given Option 2 for power normalization is already agreed in an earlier agreement, the moderator would like to check whether we could follow the majority view among the 3 alternatives on this issue. 
[FL1] Proposal 5.7-1 
Option 2-Alt 1, i.e., power normalization applied on both target channel and background channel, i.e.,  is adopted to normalize the power of ISAC channel, where  is such that  



[Moderator’s note] Regarding ‘FFS condition to select option, e.g. depending on scenario, sensing mode, number of target/EO type-2’, please provide your view on anything should be specified or not. 
[FL1] Question 5.7-2 
Companies are encouraged to provide views on whether/how to specify a condition to select Option 1 ‘no power normalization’ and Option 2 ‘with power normalization’ in the combination of target channel and background channel. 


Doppler of moving scatters

Summary on company views

Reuse 7.6.10: HW, LGE

OPPO: Maximum speed and ratio of moving scatters depends on scenarios. 
Speed of 95%-100% moving scatters follows uniform distribution between 0 and 180km/h for UAV case 
Speed of 95%-100% moving scatters is 0 for indoor case 
Speed of 50% moving scatters is 3-60km/h and speed of remaining moving scatters is 0 for UMa/UMi.
Samsung: Clarify the scope of mobility of stochastic clutters
SS: due to environmental effects such as wind-induced mobility or if there are other factors related to target channel modeling, such as target mobility.
E//
Option 1: Use the existing procedure in clause 7.6.10 in TR 38.901, which creates Doppler variations for a proportion p of the stochastic clusters in the background channel
require many new measurement campaigns
Option 2: Drop additional moving unintended targets and use the target channel model for each of these
Apple
FFS1: the maximum speed of moving scatterers should not exceed maximum speed of target, Tx or Rx
FFS2: the ratio of moving scatterers among all scatterers depends on evaluation goal.
BUPT
The Micro-Doppler may need to be considered in ISAC channel modelling, and the formula   can be used as a starting point for the modelling of the Micro-Doppler.

[Moderator’s note] Inputs on how to handle maximum speed and ratio for moving scatters are appreciated. 
[FL1] Question 5.8-1 
Companies are encouraged to provide inputs on the following FFS points. 
FFS: maximum speed of moving scatterers
FFS: ratio of moving scatterers among all scatterers


Micro-Doppler
Summary on company views

Specify function for micro-Doppler
Neutral: HW
Yes: Nokia, QC, OPPO, vivo
NO: LGE, EURECOM

UAV: QC, OPPO, IDC
Human: QC,vivo, OPPO, BUPT,IDC
Bird: OPPO

Panasonic: Discuss whether the micro-Doppler patterns are per target or per scattering point
E//: Since micro-Doppler is essential for distinguishing wanted and unwanted targets, methods to model micro-Doppler are needed for the completion of the Study Item.
OPPO:

Vivo
	Eq. 8
	Eq. 9

IDC
Table 2: Micro-Doppler functions for micro-motions of humans and UAVs.

Nokia: the micro-Doppler modeling shall be based on the dual mobility modeling of Section 7.6.10 of TR38.901 as baseline

[Moderator’s note] The following proposal should be agreeable. 
[FL1] Proposal 5.9-1
Micro-Doppler, if enabled, is generated per scattering point for a target.


[Moderator’s note] RAN1 already agreed on the placeholder for micro-Doppler. If there is remaining TU, it is nice to decide certain detailed functions to handle micro-Doppler
[FL1] Question 5.9-2
Companies are encouraged to input on the proper functions/models for micro-Doppler



Absolute delay


Summary on company views

Confirm the WA: Apple, ZTE
QC: Support the absolute time of arrival modelling for the highway and urban grid scenarios. At least for the urban grid scenario use the same parameter values as that from the UMi scenario for the TRP to UE links.
FFS: The parameter values for the highway scenario.
OPPO: Before RAN1 confirms the RAN1 #120 working assumption on absolute delay, RAN1 seeks for an agreement on a LOS scattering model with non-zero Δτ being applied, in order to retain a odelling feature that has already been agreed.

[Moderator’s note] From last meeting, the application of absolute delay in ISAC channel model is agreeable. The concern at that time is the parameter values for  may not be available. As discussed by OPPO, if the WA is confirmed, it means there is no case that absolute delay is not enabled. Consequently, the procedure in the early agreement will not happen. 

[FL2] Proposal 5.10-1 
The following working assumption is confirmed


Agreement
The following working assumption is confirmed

[Moderator’s note] Following the discussion from QC, an observation is that the channel model for urban grid, highway and HST are derived based on Uma and/or Rma. Therefore, the moderator makes the following proposal. 

[FL2] Proposal 5.10-2 
To generate the absolute delay model for sensing scenarios Urban grid, highway and HST
For Urban grid, the values of parameters for  of scenarios UMa are reused. 
For Highway, the values of parameters for  of scenarios RMa and UMa are reused for FR1 and FR2 respectively. 
For HST, the values of parameters for  of scenarios RMa are reused. 



[FL3] Proposal 5.10-2-rev1 
To generate the absolute delay model for sensing scenarios Urban grid, highway and HST
For Urban grid, the values of parameters for  of scenarios UMa are reused. 
For Highway, the values of parameters for  of scenarios RMa and UMa are reused for FR1 and FR2 respectively. 
For HST, the values of parameters for  of scenarios RMa and UMa are reused for FR1 and FR2 respectively. 



[FL2] Proposal 5.10-2-rev2 for working assumption
To generate the absolute delay model for sensing scenarios Urban grid, highway and HST, for both target channel and background channel
For Urban grid, the values of parameters for  of scenarios UMa are reused. 
For Highway, the values of parameters for  of scenarios RMa and UMa are reused for FR1 and FR2 respectively. 
For HST, the values of parameters for  of scenarios RMa and UMa are reused for FR1 and FR2 respectively. 
Note: If significant problem is found by validation, we can change the distribution of 

EO type-2 
Huawei
When sensing target is modelled with multiple scattering points, 
The EO ray is generated per scattering point, i.e. Tx-EO-STsp-Rx, Tx-STsp-EO-Rx.
For concatenation with EO rays, the EO ray is concatenated with other rays as if it is a LOS ray.

Model arbitrary orientations of type 2 EOs: E//

E//: specular reflection is modelled, if Type-2 EO is of the same size as or larger than the first Fresnel zone. Otherwise, it is not modelled
The radius of the first Fresnel zone is approximately given by:

for tx—target distance d₁ and target—rx distance d₂, and wavelength λ.

EO type-2 in background channel
Summary on company views

EO type-2 in background channel if it is modelled in target channel
Yes: Huawei, Sony, ZTE, LGE, Lenovo, EURECOM, Spreadtrum
NO: Ericsson, DOCOMO, Nokia, CMCC, BUPT, QC, CATT, CICTCI, IDC
Neutral: Xiaomi

E//: 
Since stochastic clusters have been used to generate multipath propagation in UE-BS communication channel, the need for a deterministic Type-2 EO in the background channel is not clear.
the received power of the sensing Rx’s in the ISAC model with the absence of sensing targets would be different from that in the legacy UE-BS communication channel.

[Moderator’s note] A larger number of companies perfer to not model EO type-2 in background channel, but there is still quite a few companies prefer to have it. Therefore, the moderator would like to try a proposal in the middle, say the configuration of EO type-2 can be controlled separately for target channel and background channel. 

[FL3] Proposal 6.1-1 
EO type-2 is modeled in background channel as optional feature
Whether to model EO type-2 in target channel and background channel can be configured separately. 



[FL3] Proposal 6.1-1-rev1 
EO type-2 is modelled in background channel if modelled in target channel
Supported by: HW, LG, Lenovo, SS, ZTE, Sony
EO type-2 is not modelled in background channel
Supported by: CATT, QC, vivo, SPRD, Ericsson, IDCC, DOCOMO, OPPO, Xiaomi, 

[H] LOS condition considering EO type-2
Summary on company views

Option A: HW, Nokia, QC, BUPT, Panasonic, LGE, Samsung, HW, Nokia, ZTE, EURECOM, LGE, Xiaomi, Apple, Spreadtrum, CT, Sony, MTK, NVIDIA
The LOS probability equation defined in TR38.901: HW, Panasonic, Sony, EURECOM
Opiton B: Lenovo, CATT, IDC, DOCOMO, Ericsson, IDC, CATT, SK Telecom, Tejas
Type-2 EO has no impact on LOS/NLOS condition

Option A: HW, Nokia, QC, Panasonic, LGE, HW, Nokia, ZTE, EURECOM, LGE, [SS], Xiaomi, Apple, Spreadtrum, CT, Sony, MTK, NVIDIA
The LOS probability equation defined in TR38.901: HW, Panasonic, Sony, EURECOM
Opiton B: Lenovo, CATT, IDC, DOCOMO, Ericsson, IDC, CATT, Tejas
Type-2 EO has no impact on LOS/NLOS condition

HW: The EO type2 as a large and stationary building should not be defined as a blocker according to the blockage model in TR38.901.
E//: The legacy soft LOS state is applicable to ISAC channel model
E//: 
Option B is in line with existing procedure for blocking in TR 38.901, where the blocking does not change the LOS state.
With Option A, the spatial consistency between BS-target link and BS-UE channel is broken, when the target and UE are close to each other
Option A may cause a hard transition in the channel response as the targets moves, similar to UT movement, which legacy communication channel tries to avoid
Option A is more suitable for the map-based hybrid channel model or ray-tracing than the stochastic channel stated in section 7.5 of 38.901

[Moderator’s note] To make a complete proposal, Option A is revised based on the comments from proponent companies.  Please each company provide your preferred option. Down selection should be done in RAN1 #120bis.

[FL3] Proposal 6.2-1 
Down-select in RAN1#120bis one option from the following two options to determine the LOS condition of the Tx-target link and target-Rx link?
Option A: If type-2 EO is in the LOS ray of one link, the link is determined as NLOS condition, and otherwise use the LOS probability equation defined in existing TRs to determine the LOS/NLOS condition
FFS changes to the LOS probability defined in existing TRs
FFS details on blockage by EO type-2
Option B: Use the LOS probability equation to determine the LOS/NLOS condition of one link, and then the impacts of type-2 EO is modeled by a blockage model
Note: If EO type-2 is agreed to be modelled in background channel, the agreed option is extended to LOS conditioin determination for background channel. 



[FL3] Proposal 6.2-1-rev1 
Down-select in RAN1#120bis one option from the following options to determine the LOS condition of the Tx-target link and target-Rx link?
Option A: If type-2 EO is in the LOS ray of one link, the link is determined as NLOS condition, and otherwise use the LOS probability equation defined in existing TRs to determine the LOS/NLOS condition
Supported by: HW, ZTE, Sony, QC, LG, Xiaomi, MTK, Nokia, CMCC, Spreadtrum, OPPO, vivo, 
Option B: Use the LOS probability equation to determine the LOS/NLOS condition of one link, and then the impacts of type-2 EO is modelled by a blockage model
Supported by: Ericsson, CATT (without blockage model), Lenovo, IDCC, DOCOMO, 
Option C: Use the LOS probability equation to determine the LOS/NLOS condition of one link,
Supported by: CATT, Ericsson, Nokia, Lenovo, DOCOMO, IDCC,  
Note: If EO type-2 is agreed to be modelled in background channel, the agreed option is extended to LOS condition determination for background channel. 

[H] EO type-2 for a link in NLOS condition
Summary on company views

ZTE: The pathloss of NLOS ray due to EO type 2 in the STX-SPST link or SPST-SRX link is calculated by , where  is the total propagation distance due to EO type2.
CATT: If EO type-2 is modelled when NLOS condition is determined for Tx-Target link or Target-Rx link:
The pathloss of Tx-Target link or Target-Rx link in NLOS condition with EO type-2 is calculated based on the LOS condition pathloss model
The channel impulse response equation of Tx-Target link or Target-Rx link in NLOS condition with EO type-2 should be modified as following:


[Moderator’s note] The existing behavior in 7.6.8, TR 38.901 assume the LOS ray is present, then power of ground reflection ray is calculated. The same principle is inherited for EO type-2 in LOS condition. As commented by some companies that EO type-2 is valuable for NLOS condition, the solution to calculate the path power is missing

[FL2] Question 6.3-1 
Please provide views on whether/how to model specular reflected ray of EO type-2 in a link with NLOS condition. 



[FL3] Proposal 6.3-1 
In NLOS condition, the pathloss of the ray specular reflected by an EO type 2 in the STX-SPST link or SPST-SRX link is calculated by , where 
 is a pathloss assuming a LOS condition for the STX-SPST link or SPST-SRX link
 is the total propagation distance due to EO type-2



[FL3] Proposal 6.3-1-rev1 
The pathloss of the ray specular reflected by an EO type 2 in the STX-SPST link or SPST-SRX link is calculated by , where 
 is a pathloss assuming a LOS condition for the STX-SPST link or SPST-SRX link
 is the total propagation distance due to EO type-2


Whether/how to normalize the power of target channel, background channel or the combined channel if EO type-2 is modeled?
Summary on company views

NO: Nokia, LG, vivo, CATT
Open: ZTE

[Moderator’s note] The existing behavior in 7.6.8 is to add the ground reflection ray without further power normalization. The number of EO type-2 may be large in a scenario, but number of strong EO type-2 that can be modeled for a link is always limited. Therefore, we may follow the existing behavior in 7.6.8, TR 38.901
[FL1] Proposal 6.4-1 
Additional power normalization is not considered due to the presence of EO type-2 
Note: this is aligned with the behaviour handling the power of a NLOS ray specular reflected by the ground in section 7.6.8, TS 38.901


Spatial consistency 
CATT: The existing spatial consistency model in TR 38.901 (i.e., site-specific correlation) is reused to model correlation of links between one RSU and different STs/UEs, instead of using the newly defined link correlation.
[H] General question
Is there correlation between the multiple points of a target if spatial consistency is NOT enabled?
Yes: Huawei?
HW: In Step 2 (i.e., the basic procedure), LOS/NLOS condition of the SPs within the same ST are correlated
No: vivo?

CATT
By default, initial random phase of target CPM remains unchanged even if target position changes during simulation. If spatial consistency is considered, initial random phase of target CPM may be further added in the correlation parameter list.

Concatenation Option 3 (1-by-1 random mapping of Tx-target and Tx-Rx link)
If concatenation Option 3 is used, should we update the set of generated paths during the movement of Tx, target and/or Rx?
NO: HW, Nokia, CATT, ZTE

Path dropping after concatenation of Tx-target and target-Rx link
Should we update the set of remaining paths after path dropping after concatenation during the movement of Tx, target and/or Rx?
NO: HW, CATT, ZTE

[Moderator’s note] Reading the contributions, it seems different companies have different understanding on default behavior when spatial consistency is not enabled. Let’s try to clarify it. 

[FL1] Question 7.1-1
When spatial consistency is NOT enabled, what are the understandings on the following questions?
Can we assume the Tx/target/Rx position is unchanged in a simulation drop?
Note: when position is unchanged, Tx/target/Rx velocity of Tx/target/Rx can still be modelled in the simulation, e.g., for Doppler
If changing the Tx/target/Rx position is supported, can we assume the large/small scale parameters of Tx-target link, target-Rx link and the background channel are regenerated independently?
If changing the Tx/target/Rx position is supported, can we assume the RCS component B2 and XPR/initial random phase of the target are regenerated independently?


[FL2] Proposal 7.1-1
When spatial consistency is NOT enabled, the Tx/target/Rx position is unchanged in a simulation drop



[Moderator’s note] When spatial consistency is enabled, the set of paths generated by concatenation Option 3 should not be updated during movement of Tx, target and/or Rx. Otherwise, the spatial consistency is broken. 

[FL1] Proposal 7.1-2 
When spatial consistency is enabled, the set of paths generated by concatenation Option 3 (1-by-1 random mapping) is not updated during movement of Tx, target and/or Rx. 



[FL2] Proposal 7.1-2-rev1 
When spatial consistency is enabled, the 1-by-1 random coupling generated by concatenation Option 3 is not updated during movement of Tx, target and/or Rx, if the LOS condition of the Tx-target and target-Rx links are not changed.


Agreement
When spatial consistency is enabled, the 1-by-1 random coupling generated by concatenation Option 3 is not updated per simulation drop even if Tx, target, Rx positions change during simulation.


[Moderator’s note] When spatial consistency is enabled, the set of remaining paths after path dropping after concatenation of Tx-target and target-Rx link should not be updated during movement of Tx, target and/or Rx. Otherwise, the spatial consistency is broken. 
[FL2] Proposal 7.1-3 
When spatial consistency is enabled, the set of remaining paths after path dropping after concatenation of Tx-target and target-Rx link is not updated during movement of Tx, target and/or Rx. 



[FL3] Proposal 7.1-3-rev1 
When spatial consistency is enabled, the set of remaining paths after path dropping after concatenation of Tx-target and target-Rx link is not updated per simulation drop even if Tx, target, Rx positions change during simulation.



[FL3] Proposal 7.1-3-rev2 
When spatial consistency is enabled, the set of remaining paths after path dropping after concatenation of Tx-target and target-Rx link 
Option 1: is not updated per simulation drop even if Tx, target, Rx positions change during simulation.
Option 2: can be updated even if Tx, target, Rx positions change during simulation.

[H] Cases that spatial consistency are supported or not supported
Summary on company views



Whether to consider spatial consistency for the links that are generated referring to channel models with parameter values of different scenarios
E.g., between TRP-target/UT link in one scenario and target/UT-UT link in another scenario
Not modeled: HW, Nokia, LGE, vivo

Whether to consider spatial consistency for TRP-target/UT link and target/UT-UT link, if both links are referring to same scenario though the height of TRP and UE are different, e.g., UMi, InH, InF
Not modeled: HW, Nokia, BUPT
BUPT
f the height difference between the TRP and the UT/target is significant—as in UMi, UMa, RMa, Highway, and Urban grid scenarios—the statistical characteristics of the transmitter and receiver sides exhibit notable differences
if the target-UT link follows 38.858, the condition “ASD and ZSD statistics updated to be the same as ASA and ZSA for UE-UE” applies.
Support: LGE, vivo

[Moderator’s note] Based on the discussion in last meeting, it should be quite agreeable if the two links are generated using different parameter value sets of channel model. For background channel for TRP monostatic sensing, it is straightforward there is no spatial consistency for the virtual receivers/reference points of different TRPs 
[FL3] Proposal 7.2-1
Spatial consistency is not modelled for
the links that are generated referring to channel models with parameter values of different communication scenarios
E.g., between TRP-target/UT link in one scenario and target/UT-UT link in another scenario
the background channels for TRP monostatic sensing of different TRPs



[Moderator’s note] For sensing scenario UMi, InH and InF, it is likely we use the channel model referring the same communication scenario to generate TRP-UT/ST link and UT-ST/UT link. However, as discussed by BUPT, the ASD/ZSD may still be different for the two links. Therefore, it is proposed to not model spatial consistency for the links. 
[FL3] Proposal 7.2-2
Spatial consistency is not modelled between TRP-target/UT link and target/UT-UT link for sensing scenario UMi, InH and InF



[Moderator’s note] Then, it is a question, whether/how to model spatial consistency for the virtual receivers/reference points for UE monostatic sensing of different UEs or the same UE (mobility)?
[FL3] Question 7.2-3
Whether/how the spatial consistency for the background channels for UE monostatic sensing of different UEs or the same UE (mobility) can be supported? 
Please proponent company provide values of all necessary parameters for the model, e.g., the correlation distance, etc. 


Additional parameters to be considered for spatial consistency 

Summary on company views

Any additional parameters?
New parameter for Gamma distribution of background channel for monostatic sensing: ZTE
Note: this discussion is included in 7.1-3. Let’s start from checking whether it can be modelled and what is the solution and the required parameter values
No more: HW, Nokia, LGE, vivo

[Moderator’s note] As captured in the note of the agreement, RAN1 still need to check whether certain new parameters can be considered for the new spatial consistency model. In fact, this question is also applicable to the existing spatial consistency model which is reused for TRP-UE/ST links. Therefore, the moderator makes the following general question. 
[FL1] Question 7.3-1
Which new parameters should be considered for spatial consistency?


[H] Spatial consistency between multiple scattering points
Summary on company views

Huawei: Spatial consistency among multiple scattering points of the same target could be treated as different links.
BUPT
For targets such as small UAVs, large UAVs (in RMa and UMa scenarios), and humans, where the large-scale parameters between multiple points are highly correlated, it is recommended to reuse the spatial consistency results of a single point.
For targets such as vehicle Type 1, vehicle Type 3, and large UAVs (in UMi scenarios), it is recommended to model the spatial consistency for multiple points separately.
BUPT
We suggest calculating the fixed spatial decay coefficients between target multiple points beforehand. Once spatial consistency for any single point is calculated, apply these coefficients to efficiently and accurately model ISAC multi-point spatial consistency.

The multiple scattering points of a target are handled as if multiple targets with single scattering points
Yes: vivo, LGE


Should the correlation between multiple scattering points modelled by a spatial consistency procedure or other solution?


[FL3] Proposal 7.4-1
When spatial consistency is NOT enabled, channels of the multiple scattering points of a target are uncorrelated
Spatial consistency, if enabled, for the links between BS/UT and multiple scattering points of a target are modelled as if multiple targets with single scattering point. 



[H][FL3] Proposal 7.4-1-rev1
On the relation between multiple scattering points of a target and spatial consistency
When spatial consistency is NOT implemented, channels of the multiple scattering points of a target is independently generated
OPPO, QC, CATT, Spreadtrum, SS, CMCC, Nokia
When multiple scattering points of target is modelled, spatial consistency is used
Huawei, ZTE, vivo, BUPT, DOCOMO, Ericsson, LG, IDCC, 
Spatial consistency, if enabled, for the links between BS/UT and multiple scattering points of a target are modelled as if multiple targets. 


Solutions for new spatial consistency
Summary on company views

Any preference or more options?
Option 1: global grid (aka. Unified grid) + shifting UT/ST locations
ZTE, CATT, IDC
Option 2: direct modelling on the correlation of grids of different UT/ST, e.g., Cholesky decomposition
Vivo, LGE, SPRD
Option 3: direct modelling on the correlation of grids of different UT, e.g., Cholesky decomposition
Option 4: direct modelling on the correlation of grids of different ST, e.g., Cholesky decomposition

Vivo: The complexity reduction of target-specific method can be considered, e.g., by reducing the size of grid and using the combination of interpolation and extrapolation


[Moderator’s note] It is also important for us to try to align the understanding on exact solution to model spatial consistency for ST/UT links. 

Note: Intention is NOT to discuss the solution(s) for new spatial consistency ‘link-Correlated’ using offline/online session. 
[FL1] Proposal 7.5-1
Please provide details on the preferred solutions to the new spatial consistency model of ‘link-correlated’


[H] 3D spatial consistency
Summary on company views

3D spatial consistency
the existing 2D correlation distance in Table 7.6.3.1-2 in TR39.901 is extended to 3D correlation distance: vivo HW, Xiaomi, EURECOM, Nokia, LGE, CATT, ZTE, CMCC

Vivo: Model correction of target specific 3D grid by Cholesky decomposition of correlation matrix
E//: If spatial consistency in vertical plane is not supported by ISAC channel model, vertical mobility is not supported for UAV sensing

[Moderator’s note] Companies are encouraged to check if the following proposal is agreeable. 

[FL1] Proposal 7.6-1 
The existing 2D correlation distance in Table 7.6.3.1-2 in TR39.901 is reused as 3D correlation distance for ISAC channel at least for UAV scenario



[FL2] Proposal 7.6-1-rev1 
The existing horizontal correlation distance in Table 7.6.3.1-2 in TR38.901 is reused as vertical correlation distance for ISAC channel at least for UAV scenario



[FL3] Proposal 7.6-1-rev2 
The existing 2D correlation distance in Table 7.6.3.1-2 in TR39.901 is reused as 3D correlation distance for ISAC channel at least for UAV scenario



[FL3] Proposal 7.6-1-rev3 for working assumption
Option 1: The existing horizontal correlation distance in Table 7.6.3.1-2 in TR38.901 is reused as vertical correlation distance for ISAC channel at least for UAV scenario, within same ‘Applicability range in terms of aerial UE height (defined in 36.777)’
Option 2: 3GPP assumes UAV height cannot change in a simulation drop, if spatial consistency is enabled.
Option 3: The existing horizontal correlation distance in Table 7.6.3.1-2 in TR38.901 is reused to model 3D spatial consistency for ISAC channel at least for UAV scenario, within same ‘Applicability range in terms of aerial UE height (defined in 36.777)’

Procedure A vs. B for spatial consistency
Summary on company views

Can we concluded both spatial consistency procedures A and B in 7.6.3.2 in TR 38.901 are reused to support spatial consistency of ISAC channel STX/SRX/ST is/are moving?
Both: HW, Nokia, LGE, vivo, CATT, ZTE, CMCC (B is better). Tejas
A: Nokia, SPRD

[Moderator’s note] There is limited discussions from the contributions. However, since procedure A/B are supported in the existing 38.901, it may be supported by default, subjected to RAN1 discussions. Companies are encouraged to comment on the following proposal. 
[FL1] Proposal 7.7-1
Both spatial consistency procedures A and B in 7.6.3.2 in TR 38.901 are reused to support spatial consistency of ISAC channel STX/SRX/ST is/are moving

Link level channel model
Summary on company views

Option 1: Based on existing CDL channel model, 
Alt 1: add one or more clusters representing target(s): HW (parameters up to evaluation assumptions. A range can be defined), vivo, CATT, ZTE, BUPT

Alt 2: Update the parameters of one or more cluster to represent target(s)

Option 2: Reducing the system level channel model for ISAC to single Tx and single Rx: MTK

Parameter values for the target cluster to be decided in evaluation stage: Huawei
certain modification, e.g., the delay, angle, velocity or doppler parameter to the target cluster: vivo

Ericsson: For link-level ISAC channel models,
H_ISAC=H_target+H_background still holds.
legacy CDL models are reused to model Tx-target and target-Rx links of target channel and Tx-Rx channel of background channel.
target channel is generated by concatenating Tx-target and target-Rx link


[Moderator’s note] Companies are encouraged to comment on the following proposal. 

[FL1] Question 8.1-1  
Which option is preferred to model link-level channel for ISAC? 
Option 1: Based on existing CDL channel model, 
Alt 1: add one or more clusters representing target(s)
Alt 2: Update the parameters of one or more cluster to represent target(s)
Option 2: Reducing the system level channel model for ISAC to single Tx and single Rx
Option 3: The Tx-target link and target-Rx link are modelled by separate CDL channels, concatenation is then performed to get the target channel; the background channel is modelled by another CDL channel. 
Option 4: Not supported



[FL3] Proposal 8.1-1  
The link-level channel for ISAC is generated by adding add one or more clusters representing target(s) to the existing CDL channel model
Values of parameters of the added cluster(s) can be discussed in performance evaluation stage


[FL3] Proposal 8.1-1-rev1  
The link-level channel for ISAC is generated by adding add one or more clusters representing target(s) to the existing CDL channel model
Values of parameters of the added cluster(s) can be discussed in performance evaluation stage
TDL channel model from exiting 38.901 is not enhanced for ISAC channel model


Hybrid channel model
Summary on company views

ZTE: The procedure of hybrid channel modelling with RT simulation in TR 38.901 can be reused and enhanced for sensing. Specify the following typical maps and characteristics of sensing targets to align the simulation assumptions:
Urban grid map defined in 3GPP TR 37.885 
The well-known Manhattan map from open source
Indoor map defined in IEEE 802.11 WLAN
EM parameters defined for radar material by ITU 

[Moderator’s note] ZTE provides the modifications to incorporate ISAC channel model into the map-based hybrid channel model in existing TR 38.901. Companies are encouraged to comment on defining ISAC channel based on map-based hybrid channel model. 
[FL1] Question 9.1-1  
Please provide your view whether/how ISAC channel based on map-based hybrid channel model should be supported I Rel-19. If so, how to achieve it? 

3GPP TSG-RAN WG1 Meeting #120-bis	R1-2502565
Wuhan, China, April 7th – 11th, 2025

Agenda Item:	9.7.2
Source:	Tejas Networks
Title:	Discussion on ISAC channel modelling
Document for:	Discussion and Decision
__________________________________________________________________________________
Discussion
The objectives of the study item “Channel modelling for integrated sensing and communication (ISAC) in 5G-NR” [1], listed in Rel-19, and endorsed in RAN1#103, are as follows: 

This contribution provides our view on some of these topics as captured in following subsections.
RCS modelling of the target objects
2.1 Monostatic vs Bistatic RCS
 


In the previous RAN1 meeting, the agreement shown above was made on RCS of the target. We consider monostatic RCS to be a special case of bistatic RCS, where the incident and scattered angles are identical in the bistatic RCS model. However, the indirect paths, generated either by convolution or one-to-one random ray coupling in both modes, require bistatic RCS. In contrast, monostatic RCS is computed by considering only the direct paths from the transmitter to the target and from the target back to the transmitter.
From the above agreement, we observe that the RCS pattern for a scattering point of a target in bistatic sensing mode is generated by A*B1*B2. For a single scattering point RCS of a target, A is a single value, whereas for multiple scattering points, A represents the average value of all scattering points.
The same value of A*B1 can be used for both monostatic and bistatic sensing. In bistatic mode, it applies to all paths, both direct and indirect, whereas in monostatic sensing, it is applicable only to direct paths.
Observation 1: Monostatic RCS is a special case of bistatic RCS; therefore, priority should be given to modelling bistatic RCS.
Observation 2: For a single scattering point RCS of a target, A is a single value, whereas for multiple scattering points, A represents the average value of all the scattering points.
Observation 3: The same value of A*B1 can be used for both monostatic and bistatic sensing. In bistatic mode, it applies to all paths, both direct and indirect, whereas in monostatic sensing, it is applicable only to direct paths.

From the above agreement, we observe that the component A*B1, i.e.,  is specified for each target type and expressed in the dBsm scale. This angle-dependent RCS component for a vehicle is a function of eight parameters measured across all sides of the vehicle. Depending on the vehicle’s size and type, the values in each row of the table above differ. For instance, a car and a bus may have different A*B1 components; however, A can be somewhat similar, as it is considered a large-scale parameter.
Therefore, we propose that A be treated as a single value, making the RCS values of targets of the same type but different sizes entirely dependent on the angular characteristics of the A*B1 parameter. Similarly, in the case of monostatic versus bistatic sensing, keeping A as a single value ensures that the RCS depends only on the angular characteristics of the A*B1 parameter.
Proposal 1: we propose that A be treated as a single value, making the RCS values of targets of the same type but different sizes entirely dependent on the angular characteristics of the A*B1 parameter. Similarly, in the case of monostatic versus bistatic sensing, keeping A as a single value ensures that the RCS depends only on the angular characteristics of the A*B1 parameter.
Observation 4: Depending on the vehicle’s size and type, the values in each row of the table above differ. For instance, a car and a bus may have different A*B components; however, A can be somewhat similar, as it is considered a large-scale parameter.
Modelling Background Channel


We consider dropping N reference points for modeling the background channel, which follows a certain distribution similar to the N clusters in TR 38.901, where we limit the number of clusters whose power is significantly lower than a certain threshold. However, in sensing scenarios, low-power clusters may still contribute to precise target detection/sensing Thus, it is unclear how to compute an upper limit for N while considering both monostatic and bistatic modes.
For instance, in monostatic mode, a background channel with N clusters, some of which have very low power, may not aid in accurately sensing the target. However, retaining rather than removing these low-power clusters could improve sensing accuracy in bistatic mode.
Proposal 2: In monostatic mode, a background channel with N clusters, some of which have very low power, may not aid in accurately sensing the target. However, retaining rather than removing these low-power clusters could improve sensing accuracy in bistatic mode.
FFS: how to compute an upper limit for N while considering both monostatic and bistatic modes
Modelling Type-2 EO
4.1 LOS condition of Tx-target/target-Rx link


The accurate modelling of LoS/NLoS conditions is essential for developing effective communication systems, as it influences the design and performance evaluation of various wireless technologies. Option A suggests that if a Type-2 EO obstructs the direct path in a link, the link should be classified as Non-Line-of-Sight (NLOS). Conversely, Option B recommends using existing LOS probability equations to determine the LOS/NLOS status, treating the impact of Type-2 EOs as additional attenuation factors without altering the fundamental LOS classification.
Observation 5: Option B maintains consistency with established methodologies in 3GPP TR 38.901, where blockage modelling is treated as an additive feature that does not alter the inherent LOS/NLOS state of a link. This approach allows for a more nuanced representation of the propagation environment by accounting for obstructions as factors that introduce additional attenuation rather than redefining the link's LOS status.
Proposal 3: We propose option B, utilizing existing LOS probability equations to determine the LOS/NLOS condition and modelling the impact of Type-2 EOs through established blockage models. This approach ensures consistency with the blockage model B in 3GPP TR 38.901, which provides a geometric method for capturing blocking effects by modelling blockers as rectangular screens and calculating attenuation using a knife-edge diffraction model. ​Furthermore, we recommend conducting comprehensive studies to assess the necessity and accuracy of modelling additional blockage effects from Type-2 EOs.
4.2 EO type-2 in background channel
The current discussion focuses on whether to explicitly include Type-2 Environmental Objects (EOs) in the background channel model, a topic that has elicited diverse viewpoints from various companies.​ Concerns have been raised that including EO type-2 in the background channel could introduce discrepancies in received power levels between ISAC sensing and traditional UE-BS communication channels. Additionally, questions remain regarding the necessity of modeling EO type-2 interactions in the target channel before deciding its role in the background channel. To ensure consistency and avoid redundancy, further clarification is needed on whether EO type-2 plays a critical role in ISAC performance evaluation beyond what is already accounted for in existing models.
Observation 6: The primary concern is whether incorporating Type-2 EOs would enhance the model's accuracy or merely replicate effects already captured by existing stochastic models.​
Proposal 4: We propose clarifying the necessity and intention behind explicitly modelling Type-2 EOs in the background channel.
Spatial Consistency Modelling
5.1 Cases spatial consistency is not supported

The discussion on spatial consistency exclusions has raised important considerations regarding the correlation of links in different deployment scenarios. While the proposed cases (non-co-located TRPs, different scenario parameters, varying LOS/NLOS conditions, and monostatic vs. bistatic background channels) are broadly accepted, some concerns remain. Specifically, questions have been raised about the definition of “non-co-located” TRPs and whether a clear distance threshold should be established to determine when spatial consistency is ignored.
Observation 7: The exclusion of spatial consistency for non-co-located TRPs is widely supported, but a clear definition is needed. This definition should specify the distance threshold and scenarios where TRPs are considered co-located.
Proposal 5: We propose explicitly defining a distance threshold for non-co-located TRPs to ensure consistent application of spatial consistency exclusions.

5.2 Legacy site-specific spatial consistency 
The proposal discusses reusing the existing spatial consistency model in TR 38.901 to model the correlation of links from or to the same or different TRPs. Most companies agree with this approach, emphasizing the importance of maintaining backward compatibility for ISAC channel modeling. ISAC channels are designed for the performance evaluation of both communication and sensing, maintaining backward compatibility is essential. Reusing the existing model ensures consistency, minimizes complexity, and aligns with established industry frameworks.
Observation 8: There is broad industry agreement on reusing the spatial consistency model from TR 38.901. Reusing the spatial consistency model from TR 38.901 ensures continuity, reduces complexity, and maintains alignment with existing standards, making it a practical choice for ISAC channel modelling.
Proposal 6: We propose to use the existing spatial consistency model in TR 38.901 to model the correlation of links between one TRP and different STs/UEs.
5.3 New model for spatial consistency

Accurate spatial consistency modelling is crucial for Integrated Sensing and Communication (ISAC) applications, The cases (5-7) underscore the need for advanced spatial consistency models to accurately capture the correlations inherent in such complex link configurations. A particularly pertinent aspect is the spatial consistency between multiple scattering points of the same target. By representing the target as a collection of point-like scatterers, each contributing independently to the reflected signal, the model can effectively capture the spatial consistency between multiple scattering points. This approach enhances the reliability and effectiveness of ISAC applications, particularly in complex environments.
Observation 9: In Integrated Sensing and Communication (ISAC) systems, accurately modelling spatial consistency between multiple scattering points of the same target is essential. This modelling ensures precise target detection and tracking, which are critical for applications such as autonomous navigation and environmental monitoring.
Proposal 7: We propose developing a spatial consistency model that explicitly accounts for the correlation between multiple scattering points of the same target. This model should integrate principles from multiple scattering tomography to improve the accuracy of target detection in ISAC applications.

The proposal discusses a new correlation type, termed "Dual-end Correlated," to address the correlation of large-scale parameters, cluster-specific parameters, and ray-specific parameters in ST-UT and UT-UT links. This proposal aims to enhance the realism and accuracy of channel models by incorporating spatial correlations between both ends of a communication link. Traditional channel models often consider spatial consistency primarily at one end of the link, typically focusing on either the transmitter or receiver. However, in scenarios where both ends of the link are mobile or subject to environmental variations, such as in ST-UT and UT-UT interactions, it becomes essential to account for the interdependencies of parameters across both ends.
Observation 10: The proposal introduces a "Dual-end Correlated" definition, indicating that parameters for links between STs and UTs are correlated, subject to a correlation distance. This approach aims to enhance the accuracy of spatial consistency models by accounting for the interdependencies of parameters across different links. 
Proposal 8: We support the adoption of the proposed correlation types for large-scale parameters, cluster-specific parameters, and ray-specific parameters of ST-UT and UT-UT links.
The selection of a spatial consistency model for the correlation of links between nodes of STs and UTs has been discussed. Various companies have expressed their preferences regarding different approaches, each balancing complexity, accuracy, and feasibility. Option 1 is widely regarded as a simpler and more efficient approach, as it requires only a single global reference grid, from which UT/ST-specific grids can be derived through shifts. In contrast, Option 2, which employs Cholesky decomposition, is deemed feasible only when dealing with a small number of UT/STs. For large-scale simulations, this method presents computational challenges, particularly in determining how many UT/STs should be included in the decomposition process. Given these technical considerations, the discussion has cantered on striking a balance between model accuracy and computational efficiency while ensuring flexibility in implementation.
Observation 11: Companies prioritizing simplicity and scalability can adopt Option 1, while those requiring more detailed and localized modelling can opt for Option 2 or its variations. By maintaining multiple options, the industry can support diverse implementation strategies while ensuring interoperability and innovation in spatial consistency modelling.
Proposal 9: Considering the diversity of technical preferences and operational requirements, it is proposed that all options remain available. This approach allows companies to determine the most suitable spatial consistency model based on their specific needs and deployment scenarios, ensuring flexibility while accommodating different computational and accuracy requirements.

5.4 Procedure A vs. B for spatial consistency


The discussion on spatial procedures for Integrated Sensing and Communication (ISAC) channels has centred around two procedures—Procedure A and Procedure B—both of which are defined in TR 38.901. Procedure A accounts for the sensing target’s speed and expresses the change in distance over time, while Procedure B does not include the sensing target's speed parameter. There are differing views among companies on whether both procedures should be retained. ZTE and vivo support reusing both Procedure A and Procedure B for spatial consistency in ISAC channels. Nokia and NSB, however, argue that it is unnecessary to support both procedures and advocate for the exclusive use of Procedure A. BUPT takes a more integrative approach, highlighting that Procedure A updates the channel within stationary intervals based on movement, whereas Procedure B updates the channel parameters based on spatial positions. They argue that these two methods complement each other and should both be retained to ensure spatial consistency for both stationary and non-stationary channels.
Observation 12: Each procedure addresses distinct aspects of spatial consistency, with Procedure A ensuring accurate channel updates based on movement dynamics and Procedure B accounting for position-based variations. As these methods complement each other, their combined use provides a more comprehensive and adaptable spatial consistency framework. Furthermore, both procedures are already supported in TR 38.901, ensuring alignment with existing standards while allowing for flexible implementation across different deployment scenarios.
Proposal 10: We propose to retain both Procedure A and Procedure B to support spatial consistency in ISAC channels, as they complement each other by addressing different aspects of spatial consistency.
Conclusions
We list all the observations and proposals here for quick reference
Observation 1: Monostatic RCS is a special case of bistatic RCS; therefore, priority should be given to modelling bistatic RCS.
Observation 2: For a single scattering point RCS of a target, A is a single value, whereas for multiple scattering points, A represents the average value of all scattering points.
Observation 3: The same value of A*B1 can be used for both monostatic and bistatic sensing. In bistatic mode, it applies to all paths, both direct and indirect, whereas in monostatic sensing, it is applicable only to direct paths.
Observation 4: Depending on the vehicle’s size and type, the values in each row of the table above differ. For instance, a car and a bus may have different A*B components; however, A can be somewhat similar, as it is considered a large-scale parameter.
Observation 5: Option B maintains consistency with established methodologies in 3GPP TR 38.901 [4], where blockage modelling is treated as an additive feature that does not alter the inherent LOS/NLOS state of a link. This approach allows for a more nuanced representation of the propagation environment by accounting for obstructions as factors that introduce additional attenuation rather than redefining the link's LOS status.
Observation 6: The primary concern is whether incorporating Type-2 EOs would enhance the model's accuracy or merely replicate effects already captured by existing stochastic models.​
Observation 7: The exclusion of spatial consistency for non-co-located TRPs is widely supported, but a clear definition is needed. This definition should specify the distance threshold and scenarios where TRPs are considered co-located.
Observation 8: There is broad industry agreement on reusing the spatial consistency model from TR 38.901. Reusing the spatial consistency model from TR 38.901 ensures continuity, reduces complexity, and maintains alignment with existing standards, making it a practical choice for ISAC channel modelling.
Observation 9: In Integrated Sensing and Communication (ISAC) systems, accurately modelling spatial consistency between multiple scattering points of the same target is essential. This modelling ensures precise target detection and tracking, which are critical for applications such as autonomous navigation and environmental monitoring.
Observation 10: The proposal introduces a "Dual-end Correlated" definition, indicating that parameters for links between STs and UTs are correlated, subject to a correlation distance. This approach aims to enhance the accuracy of spatial consistency models by accounting for the interdependencies of parameters across different links.
Observation 11: Companies prioritizing simplicity and scalability can adopt Option 1, while those requiring more detailed and localized modelling can opt for Option 2 or its variations. By maintaining multiple options, the industry can support diverse implementation strategies while ensuring interoperability and innovation in spatial consistency modelling.
Observation 12: Each procedure addresses distinct aspects of spatial consistency, with Procedure A ensuring accurate channel updates based on movement dynamics and Procedure B accounting for position-based variations. As these methods complement each other, their combined use provides a more comprehensive and adaptable spatial consistency framework. Furthermore, both procedures are already supported in TR 38.901, ensuring alignment with existing standards while allowing for flexible implementation across different deployment scenarios.
Proposal 1: we propose that A be treated as a single value, making the RCS values of targets of the same type but different sizes entirely dependent on the angular characteristics of the A*B1 parameter. Similarly, in the case of monostatic versus bistatic sensing, keeping A as a single value ensures that the RCS depends only on the angular characteristics of the A*B1 parameter.
Proposal 2: In monostatic mode, a background channel with N clusters, some of which have very low power, may not aid in accurately sensing the target. However, retaining rather than removing these low-power clusters could improve sensing accuracy in bistatic mode.
FFS: how to compute an upper limit for N while considering both monostatic and bistatic modes.

Proposal 3: We propose option B, utilizing existing LOS probability equations to determine the LOS/NLOS condition and modelling the impact of Type-2 EOs through established blockage models. This approach ensures consistency with the blockage model B in 3GPP TR 38.901, which provides a geometric method for capturing blocking effects by modelling blockers as rectangular screens and calculating attenuation using a knife-edge diffraction model. ​Furthermore, we recommend conducting comprehensive studies to assess the necessity and accuracy of modelling additional blockage effects from Type-2 EOs.

Proposal 4: We propose clarifying the necessity and intention behind explicitly modelling Type-2 EOs in the background channel.
Proposal 5: We propose explicitly defining a distance threshold for non-co-located TRPs to ensure consistent application of spatial consistency exclusions.
Proposal 6: We propose to use the existing spatial consistency model in TR 38.901 to model the correlation of links between one TRP and different STs/UEs.
Proposal 7: We propose developing a spatial consistency model that explicitly accounts for the correlation between multiple scattering points of the same target. This model should integrate principles from multiple scattering tomography to improve the accuracy of target detection in ISAC applications.
Proposal 8: We support the adoption of the proposed correlation types for large-scale parameters, cluster-specific parameters, and ray-specific parameters of ST-UT and UT-UT links.
Proposal 9: Considering the diversity of technical preferences and operational requirements, it is proposed that all options remain available. This approach allows companies to determine the most suitable spatial consistency model based on their specific needs and deployment scenarios, ensuring flexibility while accommodating different computational and accuracy requirements.
Proposal 10: We propose to retain both Procedure A and Procedure B to support spatial consistency in ISAC channels, as they complement each other by addressing different aspects of spatial consistency.
References
[1] 3GPP TSG RAN WG1 #120, “RAN1 Chair’s Notes” version EOM1.

[2] R1-2500999, Discussion/Decision document on “Summary #1 on ISAC channel modelling”.

[3] R1-2501654, Discussion/Decision document on “Email summary on values/pattern of A*B1 of monostatic RCS for target”.

[4] 3GPP TR 38.901, “Study on channel model for frequencies from 0.5 to 100 GHz (Release 18)” V18.0.0 (2024-03)

TDoc file conclusion not found

3GPP TSG-RAN WG1 #121-bis			R1-2502572
Wuhan, China, April 7th – 11th, 2025

Agenda item:	9.7.2 
Title:	Discussion on ISAC Channel Modeling
Source:	          National Institute of Standards and Technology (NIST)
Document for:	Discussion and Decision

Conclusion
In summary, our proposals and observations are listed as follows:

Proposal 1: 
For Vehicle, the monostatic RCS model parameters for A*B1 and B2 are tabulated as below:



Proposal 2: 
The single scattering point monostatic RCS model proposed for vehicle can be extended for large size UAV. The A*B1 model parameters and B2 Lognormal fitting parameters for mono-static RCS for large-size UAVs with single scattering points are tabulated in Table 2-2 below.



Proposal 3:
For bistatic RCS modeling of a vehicle, the radiation pattern A*B1 should characterize the RCS behavior only for bistatic angles  ranging from approximately 0° to 145°. When 145° <  ≤ 180°, phenomena such as blockage and diffraction become dominant due to the target's position near the direct line-of-sight (LOS) between the TX and RX.

Proposal 4:

Based on our measurements, the monostatic radiation pattern may not be the optimal fit for representing all bistatic configurations. Instead, we propose defining two distinct sets of radiation pattern parameters: one for the monostatic case (Proposal) and another for the bistatic case. The fitting parameters for the bistatic RCS radiation pattern are presented in Table 3-1 below.


Observation 1:
The bistatic RCS radiation pattern fitting primarily captures the specular peaks around the vehicle. We believe that modeling smaller lobes and additional scattering effects in the radiation pattern is not essential. Instead, these finer details in bistatic RCS behavior can be effectively represented using the B2 component, which accounts for stochastic variations and diffuse scattering beyond the dominant specular reflections.

Observation 2:
We observe notable correlations across multiple angle lags , indicating that the small-scale RCS (B2) exhibits some spatial (temporal) correlation. Therefore, we suggest modelling the ACF of B2 using the exponential function.  

Observation 3: 
By considering how the target rotation affects the rectangular screen size used in 3GPP Blockage model B, we can more accurately model the extent of the blocked bistatic angle and the shadowing.

Proposal 5: 
Model shadowing effect in the forward-scattering region using a blockage model. 

Proposal 6:
 3GPP TR38.901 Blockage Model B can be used as a starting point to model shadowing phenomenon in the forward-scattering region.

Proposal 7: 
We should explore how to model forward-scattering beyond shadowing region. Option 1: Continue using the blockage model, which models the combined behaviour of LOS and diffraction paths. Option 2: Use an effective RCS model based on target diffraction paths to reduce modelling complexity.


References

3GPP TSG RAN WG1 #120bis                                                                          R1-2502587
Wuhan, China, April 7th – 11th, 2025
Agenda Item:	9.7.2
Source:	Lenovo
Title:	Discussion on Channel Modelling for ISAC
Document for:	Discussion and decision

Conclusion




Proposal 1. The Initial background channel is defined as the propagation channel between the sensing Tx node and the sensing Rx node in the absence of the sensing targets.
Observation  1. Considering the sensing target object or EOs with pre-determined characteristics as an integral part of the background environment, as proposed in Option 1, invalidates the statistical modelling of [1, Subsection 7.5]. For example, assuming an AGV with a known position within the InF scenario, leads to a conditional InF channel statistics, and deviates the scenario from the initial InF statistics. 
Observation  2. Considering the sensing target object or EOs as an external add-on to an initial background/environment channel, as in Option 2, facilitates utilizing [1, Subsection 7.5] for the initial background/environment channel generation. However, as the target/EO is not an integral part of the background environment, the mutual impact (e.g., blockage) of the sensing target and environment needs to be further taken into account. 
Proposal 2. Consider the sensing target (and if considered, EOs) as an external add-on object to an initial background/environment channel, where no additional power normalization is needed between the background and target channel components. 
Proposal 3. Any methodology including a power normalization should explicitly define the modelled scenario to avoid confusion
Proposal 4. If EO is modelled in the target channel, it should be also modelled in the background channel.
Observation 3.The paths of the initial background channel, i.e., the channel without targets presence, include both paths of the background/environment channel, when the said paths are not impacted/blocked by the target (e.g., P#0, P#1 of Appendix B), or paths of the target channel (e.g., P#4, P#7, P#8, P#11, P#12 of Appendix B), when the sensing target collides with a path of the initial background channel.
Proposal 5. A high-level procedure as described in following figure can be utilized to generate the ISAC channel by first generating the paths of the initial background channel and subsequently introducing the impact (e.g., blockage, additional single or higher order target reflections) of the sensing targets.   

Observation  4. A clutter with low energy but with close/similar physical properties (e.g., position, velocity, etc.) to a sensing target may have negligible effect in the communication channel. Nevertheless, it may impact the performance of a sensing scenario, where the clutter energy is comparable with the target channel. 
Proposal 6. For the purpose of background channel modelling, study the required and supported dynamic range of a background channel model, by at least addressing the following questions: 
Question-1: What is the minimum clutter energy that needs to be modelled within the background environment channel in order to have a meaningful ISAC evaluation [i.e., a clutter with at least minimum energy threshold needs to be modelled]
Question-2: If and how the proposed large scale and small-scale parameters of 38.901 [and other related TRs] support modelling of the stochastic clutters given the above minimum energy threshold
Observation  5. The required dynamic range of modeling of a stochastic clutter depends on the sensing KPI requirements. A higher sensing accuracy require a higher SSNR and thereby require a higher dynamic range to be supported in modeling of the background channel.
Observation  6. the clutter with an energy of at least 7 dB [or a required SSNR value corresponding to a sensing task] below the energy of the target channel may impact, as a distortion/noise effect, the performance of a sensing operation. 
Observation  7. The dynamic range of the 38.901 is insufficient for modeling the background clutters for a wide range of combinations of the target RCS, distance, ISD, and required SSNR (corresponding to sensing accuracy of a task)
Observation  8. Removing the cluster dropping stage from the TR38.901 generation procedure, expands the supported dynamic range of the TR 38.901 by approximately 10 dBs in average. Nevertheless, a notable dynamic range deficit will remain even without the dropping stage.  
Proposal 7. clutter with an energy of at least 7 dB [or a required SSNR value corresponding to a sensing task] below the energy of the target channel shall be modelled in the ISAC background/environment channel. 
Proposal 8. Addition of low-energy clusters to the original random clusters generated by TR 38.901 procedure is necessary to achieve the needed dynamic range of the background channel.
Observation  9. The envisioned procedure by TR 38.901 includes an approximation of the present clusters, by removing the clusters with energy of 25 dB below the strongest cluster. From this perspective, the addition of the clusters with a total energy of 25 dB below the strongest generated cluster, as low-energy clusters, does not invalidate the original cluster statistics. 
Observation  10. While the exact statistics of the low-energy clusters are scenario dependent and may not be known, we suggest to use the same statistics as assumed for the normal clusters. As such, we may assume that the low-energy clusters follow the same delay, angle, doppler statistics as the normal clusters, as they model the same environment but smaller size/RCS/impact.
Proposal 9. Number of the low-energy clusters and the number of the rays within each cluster, can be adjusted to obtain the needed channel dynamic range, while maintaining an acceptable computational complexity.  
Proposal 10. The stochastic clutter associated with an ISAC background channel can be modeled via the following steps:
Observation  11. For the background/environment channel of a monostatic sensing, the distance of the sensing Tx-sensing Rx nodes may be short or non-existent. This invalidates the current modelling assumptions of [1, Table 7.4.1-1] where minimum distance of 10 meters for outdoor and 1 meter for indoor scenarios are envisioned between the Tx and Rx nodes.
Observation  12. The background/environment channel of a monostatic sensing scenario is dominated (in terms of channel strength, statistics etc.) by the direct path as well as the near-end reflections. However, these paths can be cancelled at the sensing Rx node via self-interference cancellation. Hence, the effective background/environment channel of a monostatic sensing operation shall represent the remaining channel paths after the self-interference cancellation with a higher priority.
Proposal 12. The NLOS paths of the background/environment channel of a monostatic sensing mode can be generated by replacing the sensing Rx position with a displaced Rx following the updates of the displaced Rx position based on the spatial consistency procedure A towards the true Rx location. 
Observation  13. For the stochastic clutter generation based on channel modeling procedure of TR 38.901, a reduced Tx-Rx distance leads to larger approximation of the clutters, where clutters with larger energy will be neglected in the modeling procedure.   
Proposal 13. Study and expand the modeling procedure of the 38.901 to compensate for the reduction of the supported dynamic range, in the generation of the stochastic clusters, resulting from the reduced Tx-Rx distance. 
Proposal 14. For the generation of the low-energy cluster/rays, [] = [180-240, 1], would be sufficient to obtain required dynamic range of the background channel for both bistatic and monostatic sensing scenarios. 
Proposal 15. When knowledge of the EOs are available, the LOS condition for the sensing Tx/Rx-target path is determined according to the available LOS probability formula, and the geometrical blockage modelling is applied subsequently as described in “Blockage model B” of [TR 38.901, Subsection 7.6.4]. 
Observation  14. The “Blockage model B” of [1, Subsection 7.6.4] provides a geometrical modelling for blockage of a background/environment channel by an object via a knife-edge diffraction model, where a determined attenuation is applied on the blocked ray. Other than the energy attenuation, the ray parameters (e.g., angle, delay) are not impacted in the proposed “Blockage model B”. 
Observation  15. Blockage of a ray can be alternatively modelled by a simple path obstruction, where the blocked ray is assumed to be eliminated from the modelling of the ISAC channel. The impact of the target (i.e., the resulting target-Rx rays from the incident blocked wave) can be further modelled via a knife-edge diffraction model or similarly to the Subsection 3.1, via RCS characterization of the target at the particular incoming/outgoing angles corresponding to the blocked path.
Proposal 16. When a target/object location coincides with a propagation path, blockage of the path can be modelled via the following options
Option 1. Utilize the “Blockage model B” of [1, Subsection 7.6.4] to obtain energy attenuation of the blocked path, apply the path attenuation on the blocked path while maintaining the path parameters (as recommended by [1, Subsection 7.6.4]). 
Option 2. Eliminate the blocked path from the ISAC channel (as an obstructed path), generate target-Rx rays from the target based on a diffraction model or an available RCS characterization of the target at the incoming/outgoing angles corresponding to the blocked path. 
Observation  16. Sensing measurements of a target may include plurality of measurements of the same or different sensing modes and at the same or different time instances. 
Proposal 17. Given a sensing target object, the ISAC channel model should remain temporally and spatially consistent for the channel realizations generated for multiple instances of the same or different sensing modes and at the same or different time instances. 
Proposal 18. Treat spatial consistency process of the sensing cluster, or sensing channel, as separate procedure than the background/environment channel, wherein each of the channel generation Steps 1-4 of Subsection 3.1 are evolved separately with necessary consistency requirements.
Proposal 19. For the background/environment channel, take the spatial consistency procedures of [1, Subsection 7.6.3] as a starting point and enhance to support 3-D movement of the target, as well as the 3-D movement of the sensing Tx, sensing Rx nodes. 
Observation  17. The fluctuation of the RCS is dependent on incidence and reflection angles, following the initial observations in [5,6]. In the other words, two sensing Rx/Tx nodes at the same time and angular condition to the sensing target but with different distances may enjoy a same RCS condition of the associated sensing target, please see Figure 19 for the description of the angular displacement. 
Proposal 20. Define, for RCS of different sensing targets, a temporal correlation distance, as well as correlation distance for the angle of incidence from a sensing Tx node and for an angle of reflection from a sensing target towards a sensing Rx node. 

3GPP TSG RAN WG1 #120bis	R1-2502624
Wuhan, China, April 7th – 11th, 2025

Agenda Item:	9.7.2

Source:	Apple Inc.
Title:	Discussion on ISAC channel modelling
Document for:	Discussion/Decision

Conclusion
In the contribution, the following observations and proposals are made: 

Radar Cross Section (RCS) considerations: 
Proposal 1: To ensure a common understanding, RAN1 should define explicitly what is meant by RCS for ISAC in the context of 3GPP. The definition should be based on classical RCS definitions such as:
RCS of a physical object is defined as the hypothetical area required to intercept the incident power at the target such that if the total intercepted power were re-radiated isotropically, the power density observed at the receiver would be produced.

Proposal 2: Based on measurements, the values of A and B for co-polarized and cross-polarized RCS may be selected from the following
Omni-directional Measurement Results

Directional Measurement Results

Note that the results are averaged across all incident angles at all frequencies



Proposal 3: On the monostatic RCS of a human with a single scattering point,
The monostatic RCS for a scattering point of the target is generated by
The values/pattern A*B1, i.e.,  is deterministic based on incident/scattered angles

Where,
,
,
The values/pattern of component A*B1 are generated by the following parameters: 


Observation 1:  With bistatic scattering RCS decreases as angular separation increases, until TX and RX approach the LOS path in which case we see an increase due to forward scattering.

Observation 2: The Forward scattering/diffraction region starts at about 70 degrees

Proposal 4: For the  model for the RCS in the bi-static case:
For an incident direction, the bistatic RCS in the backscatter direction is equal to monostatic RCS
bistatic RCS is constructed into 2 angular regions according to scattered angles
Region 1: derive the RCS based on monostatic RCS based on the following:

Region 2: RCS value including large effect of diffraction. 
Option 1: Use of forward scattering model
Option 2: Use of blockage model B in 38.901
No peak of bistatic RCS values is observed in the specular reflection direction for human

Single or Multiple Scattering Points: 
Proposal 5: To decide between modeling a target with single or multiple scattering points depends on the target type/size, the distance between sensing Tx/Rx and the target, the use case and deployment scenario and evaluation methodology

Proposal 6: 
A single scattering point with appropriate parameters may be used to represent a target in the SLS as default. 
Multiple scattering points may be used in an LLS or for use cases and scenarios where there may be a need to differentiate between target types or to track the movement of a target
FFS: the abstraction method from the multi-point model to the single point model.

Proposal 7: If a target is modelled with multiple scattering points, 
RAN1 assumes the relative locations of the multiple scattering points of a target are not changed 
Translational motion of the target can be modelled while rotational motion of the target should not be considered.
RAN1 assumes no rays are scattered from one scattering point to another scattering point of the same target


Target Channel Modeling
Proposal 8: RAN1 should limit interaction between more than one sensing target to limit the complexity of system level simulations subject to validation by measurements.

Proposal 9: The working assumption should be agreed on:
Absolute delay model (referring to 7.6.9 in TR 38.901 as starting point) is a mandatory feature for both target channel and background channel for ISAC for UMi, UMa, InH, InF
Related model referring to  values from 7-24GHz study item

Observation 3: A power threshold of 30 dB shows little change in delay spread and RSRP when compared with full concatenation with a substantial drop in complexity (68.997 taps vs. 123 taps on average) vs 20 dB. A power threshold of 40dB shows no change also with a drop in complexity. 

Observation 4: A power threshold of 30/40dB dB shows little RSRP difference with and without normalization. 

Proposal 10: Any indirect path with power metric less than 40 dB is dropped 

Proposal 11: There is no need for further power normalization of target channel after path dropping

Proposal 12: For LOS+LOS, LOS+NLOS, NLOS+LOS, the power threshold for path dropping is X=40 dB where X is relative to the strongest path in the target channel. 


Proposal 13: Option 1: ,  is generated for path i, where  is XPR ratio with  with a standard deviation of 4.4 for human targets.

Proposal 14: To normalize CPMtx,sp,rx, RAN1 should consider the following options:
Option 1: the magnitude of the diagonal elements of each component CPMsp,rx , CPMsp , CPMtx,sp  should be set to 1;  

Background Channel
Proposal 15: For background channel modeling:
Monostatic Background Channel: 
For the working assumption set N = 1.
RAN1 should decide on the values for 
Bistatic Background Channel
background channel is generated based on the channel generated as in existing TR between the real Tx and Rx for a scenario

Proposal 16: When the EO type-2 is modelled in the target channel, 
Option A: If type-2 EO is in the LOS ray of one link, the link is determined as NLOS condition, and otherwise use the LOS probability equation to determine the LOS/NLOS condition

Combined Channel: Sensing and Communications Channels
Proposal 17: to generate the combined ISAC channel Option 1 should be the default model:
Option 1: The ISAC channel of a pair of sensing Tx/Rx is obtained by summing the target channel(s) and background channel, i.e., power normalization is not performed


Proposal 18: In the case it is necessary to keep the same/similar channel power as the background channel without target perform power normalization on both target channel and background channel.


Proposal 19: The following two steps should be used to model the ISAC channel:
Step 1: Drop the cluster/path, from the target channel, of power -40dB lower than the max cluster/path power within the target channel (similar to 38.901)
Step 2: Drop the cluster/path, from the background channel, of power 25dB lower than the max cluster/path power within the background channel (38.901 procedure)

Spatial Consistency
Proposal 20: Spatial consistency is needed to model correlation between  multiple scattering points of the same target within the correlation distance. 

Miscellaneous Issues
Proposal 21: For shadow fading, the existing shadow fading model in TR 38.901 can be used for both mono-static and bi-static sensing. 

Proposal 22: Angular spread may be different at the Tx and Rx for bi-static sensing but is the same for mono-static sensing.

Proposal 23. To address the issues that are FFS:
FFS1: the maximum speed of moving scatterers should not exceed maximum speed of target, Tx or Rx
FFS2: the ratio of moving scatterers among all scatterers depends on evaluation goal.

3GPP TSG RAN WG1 #120bis		R1-2502715
Wuhan, China, April 7th – 11st, 2025
Source: 	MediaTek Inc.
Title:	Discussion on ISAC channel modelling
Agenda item:	9.7.2
Document for:	Discussion

Conclusion 
In this contribution, it discusses the ISAC channel modelling issues with following proposals:
Proposal 1: For sensing LLS channel generation, using the simplified SLS to generate the channel coefficient, then fed into the LLS simulator. FFS: how to simplify the SLS procedure for sensing LLS.
Proposal 2: At least the sensing resolution (also relevant with target size, simulation configuration parameter, etc) and the demand of the sensing service can be as two factors on selecting single or multiple scattering points for the sensing target modelling.
Proposal 3: It is suggested not to consider the interaction and relative position change of multiple scattering points belonging to the same sensing target.
Proposal 4: It is suggested not to model a propagation path from Tx to Rx interacting with more than one sensing target in the sensing channel modelling.
Proposal 5: The following mechanisms are suggested to determine the LOS condition between Tx/Rx and each multiple scattering points:
If EO is in the LOS ray of one link, the corresponding link is determined as NLOS link, otherwise, LOS probability equation is used to determine the LOS condition.
For each link, i.e., Tx-scattering point link or scattering point-Rx link, the LOS probability is used separately. FFS: whether/how to consider the relative position of multiple scattering points impact on the LOS probability.
Proposal 6: For indirect path modelling in sensing target modelling, reducing the number of rays per cluster and/or reducing the number of clusters are supported.
Proposal 7: For background channel, the power threshold for removing clusters use the received power reflected by sensing target as a reference.
Proposal 8: If NLOS path is modelled for target channel in some scenario, it is suggested that the NLOS can be modelled by EO besides using the stochastic mechanism, including EO type-1 and EO type-2.
Proposal 9: EO modelling can be enabled/disabled for ISAC channel modelling, which is up to the sensing evaluation scenario.
Proposal 10: For ISAC random clutter for background channel modelling in TRP and UE mono-static sensing mode, randomly drop at least one virtual Rx, and then the background channel is generated based on the channel generated as TR 38.901 between the real Tx and each virtual Rx for a scenario.
Proposal 11: For the combined ISAC channel, the power normalization between sensing target channel model and background model is not performed.
Proposal 12: From ISAC channel modelling perspective, a common channel modelling framework is defined for all six sensing modes, i.e.,  shall include both monostatic mode ISAC channel and bistatic mode ISAC channel.

3GPP TSG-RAN WG1 Meeting #120bis	Tdoc R1-2502726
Wuhan, China, April 7th – 11th, 2025

Agenda Item:	9.7.2
Source:	Ericsson
Title:	Discussion on ISAC Channel Modelling
Document for:	Discussion, Decision

Conclusion
In the previous sections, we made the following observations: 
Observation 1	In some sensing scenarios, the shadows are significant, and their existence may be a strong indicator of target presence. Examples are intruder detection or vehicular sensing of other vehicles and obstacles.
Observation 2	Shadow behind a sufficiently large target means the combined target and background channel needs to have lower energy than the background channel in the absence of any target.
Observation 3	It was agreed that sensing target is in the far field of sensing Tx/Rx. However, sensing Rx is likely to locate in the near field of a large target, where shadow effect needs to be taken into account.
Observation 4	For a car of size  and a frequency of 6 GHz, the far field from the car occurs at a distance of 1 km. A sensing Rx with its distance to the vehicle smaller than 1km is in the car’s near field.
Observation 5	The first alternative to model shadow is by forward scattering in target channel. RCS needs to be several orders of magnitude stronger in the shadow region than in other directions and with opposite phase to that of background channel so that  and  becomes small.
Observation 6	To get the total field, one should compute the complex (amplitude and phase) sum of the incident field and the scattered field. The presence of the metal sphere creates an obvious shadow at shorter distances. At longer distances the shadow becomes less sharp due to diffraction around the sphere.
Observation 7	If the phase relation between the incident field (background channel) and the scattered field (target channel) is not considered correctly, the sum of them will instead give an unphysical signal strength increase behind the target
Observation 8	Forward scattering option has multiple disadvantages.
	With the very strong forward scattering component, it is difficult to tabulate RCS since it will vary by orders of magnitude as a function of angle. The forward scattering also has a strong frequency dependence, making it even more difficult to tabulate.
	The amplitude and phase of the RCS needs to be very precisely modeled to cancel 
	The RCS needs to be complex, otherwise it cannot have a negative phase, which is in conflict with the current agreement on scalar RCS modeling.
	Since the current RCS model doesn’t include a phase, it will not give the intended cancellation of . Instead, a forward scattering RCS model of this sort will create an energy increase behind the target, which breaks the laws of physics.
	The “mean value of the RCS” is totally dominated by the forward direction
	The RCS is very large, but the received power is very small. Therefore, RCS cannot be used for link budget analysis!
	The RCS needs to be dependent on both Tx-target distance and target-Rx distance to generate the correct “depth” of the shadow
Observation 9	The second alternative of modelling the shadows is to apply the existing blockage model to background channel so that  is reduced in the shadow region.
Observation 10	Blocking can simplify RCS modelling tremendously. Without the very strong forward scattering component, RCS is much easier to model.
Observation 11	Interaction between targets is critical, when one target’s shadows have significant impacts on another target, i.e., when incident or scattered rays of the second target are severely attenuated.
Observation 12	The blockage of one target can be considered in the Tx-target and/or target-Rx links of another target channel depending on sensing mode.
Observation 13	For outdoor human scenario, the type of sensing targets which may be evaluated in future study is not limited to pedestrian and can be cyclists, E-Scooter, and motorcyclists.
Observation 14	There is no discussion on types of unintended targets and their modelling, including RCS, CPM, and velocity.
Observation 15	Without modelling of unintended objects, the SID’s objective of distinguishing targets from unintended objects cannot be fulfilled.
Observation 16	Bistatic scattering RCS from trees are available in the literature.
Observation 17	Some of the tree scattering will have non-zero Doppler due to the effect of wind, which will challenge clutter suppression in sensing algorithms
Observation 18	Bistatic RCS is needed in all target channels, also the monostatic channel.
Observation 19	Discontinuities in the RCS cause signals that are not bandlimited and non-physical artifacts in the Doppler spectrum, as seen in the simulation at time t=15s.
Observation 20	Some RCS proposals result in significant lobes in the forward scattering region, making shadowing difficult to model.
Observation 21	The overall radar cross-section, including the stochastic B2, must be continuous over the four angles to guarantee spatial consistency.
Observation 22	Discontinuous behavior leads to non-physical artifacts in the channel, including very high Doppler frequencies and spurious out-of-band artifacts.
Observation 23	For mono-static sensing mode, mono-static RCS modelling, where the incident angle and scattered angle are the same, is needed to generate the direct path of target channel, and bi-static RCS modelling is needed for indirect paths.
Observation 24	With 1:1 random ray pairing, one mono-static RCS value is needed to generate the direct path, while nearly 1200 bi-static RCS values are used to generate the indirect paths.
Observation 25	Both mono-static and bi-static sensing modes need thousands of bistatic RCS values for a target channel, while mono-static sensing mode may additionally need a mono-static RCS value for the direct path of target channel, if any.
Observation 26	Value A of mono-static RCS for some target types were agreed. It is unclear whether bi-static RCS will have its own value A and how A values of mono-static RCS and bi-static RCS will be used to calculate power scaling factor.
Observation 27	If value A, B1, and B2 for bi-static RCS are derived independently from mono-static RCS, power scaling factor of value A of mono-static RCS is applied to direct path, and that of bi-static RCS to indirect paths before they are added together.
Observation 28	If value A of mono-static RCS is used to derive B1 and B2 of bi-static RCS, it is likely that B1 and B2 of bi-static RCS will generate non-normalized power in small scale.
Observation 29	Angle-dependent RCS model of a target is provided for a given target’s local coordinate system.
Observation 30	Departure angles from sensing Tx and arrival angles at sensing Rx are usually given in the GCS, which have to be transformed into LCS based on the orientation of the target. Such a transformation between GCS and LCS to derive RCS is by implementation.
Observation 31	The prerequisite of polarization matrix [1 0; 0 -1] for the LOS ray and diagonally dominant polarization matrix for NLOS rays is that BS and UE’s field patterns are aligned in GCS.
Observation 32	CPMsp,rx and CPMtx,sp are generated by reusing polarization matrix of BS-UE channel in 38.901, implying that field patterns of target, Tx, and Rx are aligned with GCS.
Observation 33	To be able to combine CPMsp with CPMtx,sp and CPMsp,rx via a simple matrix multiplication as agreed in RAN1#118bis, the three matrices need to all be related to the same definition of  and .
Observation 34	When objects move and rotate, their scattering properties do not change in the local coordinate system of the object, similar to the field patterns of BS and UE. This is why scattering (RCS) and cross-polarisation (CPM) is modelled in the coordinate system of the object
Observation 35	If  is defined in a Local Coordinate System (LCS), and LCS of the target is always aligned with GCS, i.e., no change of orientation during the movement, transformation procedure between LCS and GCS is not needed. A change of target orientation can be supported by reusing the same procedure
Observation 36	If  is defined in a Global Coordinate System (LCS), rotation of target is not supported by ISAC channel model.
Observation 37	Both RCS component B2 and XPR of target are generated for each path, namely they are angle specific.
Observation 38	In 36.777, only horizontal mobility is supported for aerial UEs. Vertical spatial consistency is not supported.
Observation 39	Measurements and simulations of the monostatic BS background channel in the UMa scenario shows rich multipath spanning absolute delays from almost zero to several microseconds.
Observation 40	The monostatic BS background UMa channel when modelled according to the working assumption and with parameter values from [27], does not reproduce important characteristics from measurements or raytracing. In particular, the channel is too sparse, it has backscattering from the sky, and there is no backscattering from objects near the gNB.
Observation 41	The shortcomings of the background monostatic channel according to the working assumption from RAN1#120 do not seem to be possible to mitigate by parameter tuning.
Observation 42	Simulations of the monostatic BS background channel in the Indoor Office scenario shows rich multipath spanning absolute delays from almost zero and all azimuth and elevation directions.
Observation 43	The behaviour such as the absolute delay, angular distribution and richness of the monostatic background channel seen in the measurements and raytracing experiments is almost impossible to reproduce using the virtual Rx method in the working assumption.
Observation 44	Doppler due to moving scatterers (clusters) in the environment is modeled in TR 38.901 clause 7.6.10 using a maximum speed  of the scatterers and a proportion  of the scatterers (clusters) that are mobile.
Observation 45	The existing guidance on  and  in TR 38.901 does not cover sensing scenarios.
Observation 46	For sensing, Doppler due to moving scatterers (clusters) in the environment can affect both the target channel and the background channel.
Observation 47	Moving scatterers in the background channel can have a profound impact on sensing performance.
Observation 48	In a measurement of a SMa/RMa BS-BS background channel, several paths (clusters) show non-zero Doppler shifts.
Observation 49	In a measurement of a UMa BS-BS background channel, several paths (clusters) show power variations over time.
Observation 50	The power variations could tentatively be connected to moving objects in the environment that had LOS to both Tx and Rx.
Observation 51	The channel model must include spurious propagation paths that are not related to the target that have similar gains as gains of the target-related paths.
Observation 52	In 38.901, power normalization is not updated due to the new reflection path via ground.
Observation 53	For sensing, absolute delay can be regarded as an indicator of range, and a larger delay implies a longer path length.
Observation 54	Many channels essential for the sensing scenarios lack parameterization of the NLOS excess delay . If unaddressed, this may lead to an incomplete ISAC channel model that cannot be used to determine range to a target via the absolute delay.
Observation 55	The impact of a blocker in existing channel models is restricted to adjusting the amplitudes of paths that have previously been generated assuming a certain LOS state.
Observation 56	The presence of the blocker does not trigger a re-evaluation of the LOS state nor regeneration of paths in existing channel models.
Observation 57	Option B is in line with existing procedure for blocking in TR 38.901, where the blocking does not change the LOS state.
Observation 58	Option A allows the blocker to determine NLOS condition. Not only does it go against the existing blockage procedure, but also the spatial consistency between BS-target link and BS-UE channel is broken, when the target and UE are close to each other.
Observation 59	Legacy communication channel avoids a hard transition between LOS and NLOS states due to UT mobility by using soft LOS state.
Observation 60	Option A may cause a hard transition in the channel response as the targets moves, similar to UT movement, which legacy communication channel tries to avoid.
Observation 61	With Option A, simulation stops with the change of LOS/NLOS state. It puts a constraint on targets’ movement and hinders and disables target tracking.
Observation 62	Option A is more suitable for the map-based hybrid channel model or ray-tracing than the stochastic channel stated in section 7.5 of 38.901.
Observation 63	Specular reflection is a distance-dependent phenomenon, and it occurs when the object is of the same size as or larger than the first Fresnel zone.
Observation 64	Restricting the orientation of the reflective surface makes NLOS sensing easier than in reality where the orientation of the reflective surface can be arbitrary.
Observation 65	Since stochastic clusters have been used to generate multipath propagation in UE-BS communication channel, the need to model Type-2 EO in background channel is not clear.
Observation 66	Type-2 EO if modelled in background channel would lead to the consequence that the received power of the sensing Rx’s in the ISAC channel model in the absence of sensing targets is different from that in the legacy UE-BS communication channel.
 Based on the discussion in the previous sections we propose the following:
Proposal 1	Support blockage model B in 39.901 to model shadows, including
	modelling blockage in the background channel of the target
	modelling interactions between the targets when needed by introducing blockage in the Tx-target and target-Rx link of another target
Proposal 2	Study RCS of more specific types of intended and unintended targets and use the list of objects in Table 1 as a starting point.
Proposal 3	Use the following bistatic RCS model for a single tree: A*B1 with a constant level of 10 dBm2 and a single lobe in the forward direction with A*B1 increasing to 23 dBm2. The B2 standard deviation is approximately 3 dB.
Proposal 4	Consider a (larger) fraction of the RCS to correspond to a fixed scattering point representing static parts of the tree such as the trunk, and another (smaller) fraction of the RCS to correspond to moving scattering points representing leaves and branches.
Proposal 5	For the bistatic RCS of birds, use an isotropic model with A between -40 to -20 dBsm for a single bird, and A = 0 dBsm for a migrant flock.
Proposal 6	Since micro-Doppler is essential for distinguishing wanted and unwanted targets, methods to model micro-Doppler are needed for the completion of the Study Item.
Proposal 7	Focus modelling only on bistatic RCS and define the monostatic RCS in terms of the bistatic RCS, .
Proposal 8	The modelled RCS should be reciprocal, i.e., the value of the radar cross-section should not change if the signal source and the receiver are reversed.
Proposal 9	The bistatic RCS model should have a small, close-to-zero value in the forward scattering region if shadowing of the object is modelled using a blocker.
Proposal 10	The modelled RCS should be continuous in the incidence zenith angle and azimuth and the scattering zenith angle and azimuth.
Option 1-D:  and the application range is 160~180°.
Proposal 11	To model the scattering off an upright human, we suggest the following bistatic RCS model: , where  is an attenuation factor defined in terms of the bistatic angle  as  and  is a modified version of the antenna radiation pattern from TR38.901 defined in decibel scale as follows .
Proposal 12	B2 must be continuous over the incidence and scattering angles.
Proposal 13	Model the stochastic B2 with C random scattering centres as .
Proposal 14	Regarding ‘FFS: this allows different values for monostatic and bistatic sensing, if needed’, the same RCS component A is used for monostatic and bistatic sensing.
Proposal 15	For a type of target, mono-static RCS and bi-static RCS constitute the whole RCS to derive value A, B1 and B2. Such A is used to calculate power scaling factor.
Proposal 16	Support any orientation of target by defining  in a Local Coordinate System (LCS) and reusing the procedure for the support of arbitrary orientation of BS and UE in section 7.1 of 38.901
Proposal 17	CPMsp must be specified in a local coordinate system, in which the z-axis is parallel to the z-axis in the global coordinate system, .
Proposal 18	If the change of orientation leads to a change of z axis, such as a vehicle driving on/off a slope, rotation procedure is needed because the cross-polarization matrix is no longer diagonally dominant.
Proposal 19	B2 and XPR of targets, which are the random variables, should be considered for spatial consistency to address target movements in a simulation.
Proposal 20	Angle-specific random variables, B2 and XPM of the target, should be spatially consistent between adjacent angles, i.e. the random variables should not change abruptly for small changes in the angles.
Proposal 21	If spatial consistency in vertical plane is not supported by ISAC channel model, vertical mobility is not supported for UAV sensing.
Proposal 22	The monostatic background channel for UEs or for indoor gNBs can be modelled using clutter that is randomly distributed in 3D.
Proposal 23	Revert the working assumption from RAN1#120 and continue study Option 2 and Option 3 in the RAN1#118 agreement.
Proposal 24	Encourage companies to perform further measurements of BS-BS background channels to quantify the Doppler variations due to movement in the environment.
Proposal 25	Model movement in the environment using additional unintended targets modelled by Type-1 EOs.
Proposal 26	Include spurious targets (Type-1 EO) in the target channel to model spurious paths with weak power and Doppler shift.
Proposal 27	Study how to update 38.901 such that the background channel has propagation paths with similar gains as the paths of the target channel.
Proposal 28	Study if the threshold in step 6 “generate cluster powers” in 38.901 needs to be adjusted for sensing.
Proposal 29	The modelling of sensing targets and Type-2 EOs in target channel would not affect the power normalization of stochastic target channel.
Proposal 30	Given target channel contains orders of magnitude lower power than background channel, there is no need of power normalization for background channel due to the presence of targets.
Proposal 31	Since the delay of the direct path is absolute delay, delay of indirect paths should be absolute delay too.
Proposal 32	Delay of background channel should be absolute delay too, otherwise the combined impulse response of target channel and background channel will be misaligned in time domain.
Proposal 33	For absolute delay modelling of Tx-target, target-Rx, and background channels in scenarios not covered by existing TR 38.901 or in scope of AI9.8, use . Add the following note in section 7.6.9 in TR 38.901: “For scenarios and links not covered by Table 7.6.9-1, use . Caution: this value is not supported by any measurements or studies and could have an adverse impact on ranging estimates”.
Proposal 34	Type-2 EO has no impact on LOS/NLOS condition.
Proposal 35	The legacy soft LOS state is applicable to ISAC channel model.
Proposal 36	specular reflection is modelled, if Type-2 EO is of the same size as or larger than the first Fresnel zone. Otherwise, it is not modelled.
Proposal 37	Model arbitrary orientations of type 2 EOs.
Proposal 38	Type-2 EO is modelled in the target channel only.
Proposal 39	It needs evaluation whether BS-aerial UE in 36.777 can be reused for terrestrial UE-UAV link and terrestrial UE-aerial UE channel, especially for indoor UEs.
Proposal 40	It needs evaluation whether BS-aerial UE in 36.777 can be reused for aerial UE-UAV link, because it requires changing BS height from at most 35m to up to 300m (aerial UE height).
Proposal 41	Both aerial UE and UAV can be of any same or different heights in the large range of [1.5m, 300m]. It needs consideration whether/how LOS probability, pathloss model, shadow fading parameters for different UAV heights in 36.777 can be extended to support combinations of two heights of aerial UE and UAV.
Proposal 42	For link-level ISAC channel models,
	 still holds.
	legacy CDL models are reused to model Tx-target and target-Rx links of target channel and Tx-Rx channel of background channel.
	target channel is generated by concatenating Tx-target and target-Rx link

TDoc file unavailable

3GPP TSG RAN WG1 #120-bis	R1-2502776
Wuhan, China, Apr 7th – 11th, 2025

Title 	: Discussion on ISAC Channel Modelling
Source 	:  NTT DOCOMO, INC.
Agenda item	:  9.7.2
Document for:  Discussion

Conclusion
In this contribution, we provided our views and discussions on the ISAC channel modelling. The following proposals are made:

Proposal 1: In case of modelling single scattering point representative for a rectangular flat plate, the bistatic RCS value of back scattering region (Region 1) and specular reflection region (Region 2) can be calculated using the following formulas:
Case 1: Rectangular flat plate located in vertical planes
            
        
Case 2: Rectangular flat plate located in horizontal plane
                          
 
=
 [=-30]

Proposal 2: The blockage model B in TR38.901 can be used to model the forwarding scattering and blocking effect (Region 3) of a target.
                                                     
Proposal 3: For monostatic, the following values of component A, B2 can be used for RCS model 2 of human
Component B1: 0 dB 
Component B2: using the same value as model 1
standard deviation: 3.94 dB
Component A: 
Option 1: Using antenna pattern:


[=20]
Option 2: Using the following formula
 

[=0.33 ]
=-1.37 [dBsm]
[]

Proposal 4: For bistatic, the following values of component A, B2 can be used for RCS model 1 of human:
Component A: -9.4 dBsm
Component B1: 0 dB 
Component B2: using log-normal distribution
Mean: 0 dB
Standard deviation: 4.2 dB

Proposal 5: For bistatic, the following values of component A, B2 can be used for RCS model 2 of human in the Region 1 and Region 2:
Component B1: 0 dB 
Component B2: using log-normal distribution
Mean: 0 dB
Standard deviation: 4.2 dB
Component A: Using the following formula
, ]
=-9.4 [dBsm]
[=30]
 
[a=b= ]

Proposal 6: For modelling vehicle, AGV, UAV with multiple scattering points, the bistatic RCS A*B1 i.e.,  value of each scattering point can be calculated by using following formulas:
, ], in range of                       
, outside range of     					
: using the same value as monostatic case
: 
 for vertical faces (front, left, back, right):
                  
 for horizontal faces (roof, bottom):
              
[a=b= ]
[ 
The table for vehicle, AGV

The table for large UAV


Proposal 7: When a target is modelled multiple scattering points Ns and each point has RCS component , the total RCS component A*B1 of each pair of incident and scattering angles for the target is defined as below:


Proposal 8: When the EO type-2 is modelled in the target channel, use the LOS probability equation to determine the LOS/NLOS condition of one link, and then the impacts of type-2 EO is modelled by blockage model B.

Proposal 9: EO type-2 should not be modelled in background channel.

3GPP TSG-RAN WG1 Meeting #120b                                                              R1-2502814
Wuhan, China, April 7 – April 11, 2025

Source:	Panasonic
Title: 	Discussion on ISAC channel modelling	
Agenda Item:	9.7.2
Document for:	Discussion

Conclusions
Based on the discussion above, we propose the following:

The channel modelling methodology should be compatible with legacy communication channel modelling in the cases of bistatic sensing modes.
FFS: monostatic sensing mode scenario
For ISAC channel modeling, RAN1 should focus on the sensing channel without considering spatial consistency between communication and sensing channels.
No further power normalization of target channel is performed after path dropping.
Support Alt3: the target channel of a target will replace one cluster in the background channel without power normalization
If the type-2 EO blocks the LOS, the link is determined as NLOS condition. Otherwise, the LOS probability methodology defined in TR 38.901 is used to determine the LOS/NLOS condition. 
The LOS probability of the target channel and background channel are determined independently.
Define criteria how to determine whether a target example vehicle is modeled with a single or multiple scattering points
The RCS value of the entire target is the linear summation of the RCSs from the scattering points of the entire target.
Study whether and how to consider the changes of relative locations (i.e., micro motion) of the multiple scattering points in the modelling of delay and angle of a direct/indirect path. 
Discuss whether the micro-Doppler patterns are per target or per scattering point. 
Additional aspects, for example crosstalk, of the direct Tx-to-Rx channel should be considered in the case of modeling the target channel of monostatic sensing mode.

3GPP TSG RAN WG1 Meeting #120-bis  	          	     		R1-2502821
April 7-11, 2025
_____________________________________________________________________Agenda item: 9.7.2
Source: LG Electronics
Title: 	Discussion on ISAC channel modeling
Document for: Discussion and decision

Conclusions
In this contribution, the issues related to the ISAC channel modeling were discussed. The following observations and proposals were made as conclusions.
Observation 1: Given the bistatic mode is the most general case of sensing, three regions of scattering are traditionally differentiated based on the value of bistatic angle.
Observation 2: The mean value and variance of the bistatic RCS depend on the bistatic angle and tend to be less than that of the monostatic (backscattering) RCS in most cases.
Observation 3: The RCS in the forward scattering region behaves differently compared to the RCS in backscattering and bistatic regions. The forward scattering RCS is typically much higher than the backscattering and bistatic RCSs. Beyond that, the variance of forward scattering RCS is close to zero.
Observation 4: UAV scenarios for ISAC are not homogeneous, i.e. have different channels characteristics for significantly different object heights. Developing the universal approach that will cover both aerial and ground object and ensure spatial consistency between any points in space may be difficult, so we may divide the scenarios in two different cases: same-level TX-ST- RX and different levels TX-RX and ST
Observation 5: Sum-of-Sinusoids spatial correlation modeling approach considered here is suitable for full 3D modeling of mutually correlated TX-RX, TX-ST and ST-RX links, with arbitrary movement of ST and RX. Although we cannot require mandatory methodology of spatial consistence modeling, the described approach can be recommended as the baseline for calibrations. 
Proposal 1: Adopt construction of bistatic RCS into 3 angular regions using the value of bistatic angle as the distinctive feature.
Proposal 2: Model the monostatic RCS of large size UAV (UAV Option 1) as the product of the angular dependent component A*B1 parameterized according to Table 1 and the component B2 having the standard deviation σ = 1.47 dB.
Proposal 3: Model the monostatic RCS in line with the Human RCS model 2 as the product of the angular dependent component A*B1 parameterized according to Table 2 and the component B2 having the standard deviation σ = 1.47 dB.
Proposal 4: Model the monostatic RCS of animal as the product of the angular independent component A = 1.5 dBsm, the component B1=1 and the component B2 having the standard deviation σ = 3.94 dB.
Proposal 5: Model the bistatic RCS as a product of the monostatic RCS  and the deterministic function of the bistatic angle so that , . The parameters  is determined by the boundaries of the forward scattering region.
Proposal 6: Model the forward scattering RCS as a deterministic function , where angles  are determined w.r.t. the Tx to target line, Daz and Del are the effective extents of sensing target in azimuth and elevation domains, respectively. Define the angular width of the forward scattering region (centered at ) as  [rad].
Proposal 7: Consider adoption of the fully 3D spatial correlation model, supporting full 3D mobility for both the ST and UE for vehicular/pedestrian/low altitude UAV (same-level case).
Simulations of arbitrary mutual movements of the ST and RX units should be done with proper correlations between TX-ST, TX-RX and RX-ST links if they all located in the similar propagation conditions.
For high-altitude UAV links, consider introduction of TX-ST(UAV) link model with different propagation and spatial correlation properties. 
Proposal 8: Additional studies needed for defining the vertical correlation distance for Urban/Vehicular scenarios, as well as both horizontal and vertical correlation distances for the high-altitude UAV cases. Initial proposals can be found in Table 4.

3GPP TSG RAN WG1 #120-bis			R1-2502850
Wuhan, China, April 7th – 11th, 2025

Agenda item:	9.7.2
Source: 	Qualcomm Incorporated
Title: 	Discussion on ISAC Channel modeling
Document for:		Discussion

Conclusion
We have made the following proposals:
Proposal 1: Support the following power normalization between the target and the background channel:
, where  is such that 

Proposal 2: Support the absolute time of arrival modelling for the highway and urban grid scenarios. At least for the urban grid scenario use the same parameter values as that from the UMi scenario for the TRP to UE links.
FFS: The parameter values for the highway scenario. 

Proposal 3: Do not introduce a power threshold for path dropping after concatenation, i.e. X=-Inf. 

Proposal 4: Introduce a set of low-power clusters in the background channel which have a power that is in the order of the ISAC target channel’ sensing clusters. 

Proposal 5: At least for a vehicle, support a small number for XPR to be used (e.g. -40 dB or lower), or even 0. 

Proposal 6: At least for a human, support a number for XPR of the order of 0 dB. 

Proposal 7: With regards to RCS modelling, independently generate the B2 variable across angles. 
Proposal 8: With regards to the EO Type-2 in the target channel and the determination of the LOS condition, support Option A.
Proposal 9: With regards to doppler modelling, support specifying a function for micro-doppler modelling for the UAV and human outdoor sensing (e.g. VRUs) scenario in this release. 

Proposal 10: For TRP/UE to aerial UE for FR2, support reusing the channel model of FR1. 
Proposal 11: For aerial-UE to aerial-UE, support reusing the D2D channel model from 36.843 A.2.1.2 is used.
Proposal 12: Perform the diagonal-term normalization of the effective polarization matrix (CPM) after the concatenation step to ensure that the effective CPM is normalized for each concatenated ray.  
Proposal 13: When EO type-2 is included in a deployment, its impact is modelled only in the ISAC target channel.
Proposal 14: With regards to RCS modelling, independently generate the B2 variable across angles. 
Proposal 15: With regards to the bistatic RCS, support the following main principles:
Model a peak in the specular reflection direction
Model a peak in the backscattering direction: Peak equals the monostatic RCS in the incident direction
Model a local maximum (“peak”) and/or a local minimum (“shadow”) in the forward scattering region. 
Support both options for forward compatibility of the channel model
Proposal 16: With regards to RCS modelling for a pedestrian, for each scattering point, for each polarization, use RCS modelling Option 2:
For model 1, for a child, support a component A which is 5 dBsm lower than the adult:
Component A: -6.37 dBsm
Component B1: 0 dB (already agreed in RAN1#118bis)
Component B2: 
For model 2, 
With regards to the dependency on incident/scattered angles support Alt. 1 (formulated similar as the antenna radiation power pattern in 38.901)
support B1 to depend on the elevation.
Proposal 17: Introduce precipitation modelling as an Object creating Hazards on Roads/Railways Sensing Targets.
Proposal 18: Support adding an object type for “precipitation modelling” with the following modelling for backscatter effects at short distances and small velocities:
Backscatter effect: For a 3-D volume, enclosing the Tx/Rx/Object, support dropping multiple scatter-points, up to N points, where N is FFS. 

Proposal 19: Support including an attenuation factor for incorporating precipitation effect that grows with distance.

3GPP TSG RAN WG1 Meeting #120b			    	R1-2502923
Wuhan, China, April 7-11, 2025
Source 	: CAICT
Title 	: Considerations on ISAC channel modelling
Agenda Item	: 9.7.2
Document for	: Discussion / Decision 
Introductions 
In the meeting for the study on ISAC channel modelling in RAN1#120, the following agreements have been reached:
In this paper, we will present our views on some remain issues about ISAC channel modelling. Observations and proposals are put forward accordingly. 
Discussions
Polarization matrix normalization
From our view, the normalization on the polarization of a direct/indirect path, i.e., CPMtx,sp,rx= CPMsp,rx . CPMsp . CPMtx,sp, might not be necessary considering that each component in the product has been normalized. And in the low power path dropping process the CPM will be considered. 
Proposal1: Normalization on the polarization of a direct/indirect path, i.e., CPMtx,sp,rx= CPMsp,rx . CPMsp . CPMtx,sp is not supported and CPM is considered for dropping path lower than certain threshold.
Power normalization between target channel and background channel
In the agreements reached before, we have the following options are supported to generate the combined ISAC channel 
Option 1: The ISAC channel of a pair of sensing Tx/Rx is obtained by summing the target channel(s) and background channel, i.e., power normalization is not performed. 
Option 2: As an additional modelling component, power normalization is performed when summing the target channel(s) and background channel, to keep the same/similar channel power as the background channel without target. Down select between
Alt 1: Power normalization on both target channel and background channel 
Alt 2: Power normalization on background channel only
Alt 3: the target channel of a target will replace one cluster in the background channel
It is suggested to support to adopt Option2 considering the target channel and the background channel are essentially two components of ISAC channel and we can adopt the approach of power normalization—similar to how we modeled communication channels previously—to maintain consistency in the modeling process.
Proposal2: Support to adopt power normalization for the combination of target channel and background channel.
2.3 Research on background channel characteristics 
In order to analyze the background channel characteristics of the small-scale parameters for monostatic, the ray tracing simulation of a monostatic BS is performed in urban environment, as shown in Fig.1. Ray tracing results for five buildings of top view shown in fig(a) ; 3D reconstruction image based on the channel data are drawn by inversion Cartesian coordinates under the spherical coordinate system in fig(b) ; PDAP is shown in fig(c).

Fig.1 Simulation analysis diagram of monostatic
Through the comparative analysis of the three figures in Fig.1, it can be seen that the background channel of monostatic have a strong correspondence between the shape of the building. Channel cluster related to building 4 which BS deployed on has large angle spread and strong power. Channel clusters related to buildings 1,2,3 and 5 far away from BS have relative small angle spread and less power. Therefore, we can consider integrating the corresponding multi-paths related to one building into a cluster to conduct more detailed analysis and modeling of small-scale parameters.
To study the relationship between the intra-cluster parameters and average delay, the building was decouple from environment, and monostatic was simulated in a single building environment, as shown in the left figure of Fig.2. At the same time, combined with the idea of statistics, multiple base stations are uniformly scattered from two dimensions from the perspective of distance, as shown in the right figure, to analyze the characteristics of intra-cluster parameters through a large number of base stations using ray tracing channel parameters. The simulation parameters are configured as described in Table 1.

Fig.2 Simulation scenario and BS deployment diagram
Table 1 Simulation Configurations
As shown in Fig.3, where the horizontal axis is the power-weighted average delay and the vertical axis is the angular spread. The following observations can be derived. 
This is obviously different from the fixed intra-cluster angle spread between different clusters in TR 38.901. Intra-cluster angle spread varies greatly with average delay.
As the average delay increases, the overall trend of the azimuth angle spread decreases monotonically.
As the average delay increases, the overall trend of the zenith angle spread first increased and then decreased.
Mathematical formulas are derived to fit these varying trends. Horizontal angle spread is as follows.

The unit of is degree， is altitude difference of building and BS，the unit of which is meters, is average delay, the unit of which is ns.
Azimuth angle spread changes according to geometric relations as follows.

in which, . The unit of  is degree. 

Fig.3 Analysis of intra-cluster AS varing along with average delay
Observation 1: Intra-cluster parameters of monostatic background channel vary between different clusters, which is quite differently with the model design in TR38.901. Mathematical formulas can be derived to fit these varying trends along with average delay and geometrical relationships.


Conclusions
In this contribution, we have presented our considerations on some remain issues about the ISAC channel modelling and put forward the following observations and proposals:
Proposal1: Normalization on the polarization of a direct/indirect path, i.e., CPMtx,sp,rx= CPMsp,rx . CPMsp . CPMtx,sp is not supported and CPM is considered for dropping path lower than certain threshold.
Proposal2: Support to adopt power normalization for the combination of target channel and background channel.
Observation 1: Intra-cluster parameters of monostatic background channel vary between different clusters, which is quite differently with the model design in TR38.901. Mathematical formulas can be derived to fit these varying trends along with average delay and geometrical relationships.

References
RP-234069, New SID: Study on channel modelling for Integrated Sensing And Communication (ISAC) for NR, Nokia, Nokia Shanghai Bell, Dec. 2023.
IMT-2020(5G) Promotion Group, “Study on 5G-Advanced ISAC Technologies in RAN”, April 2024.
IMT-2020(5G) Promotion Group, “Study on Evaluation Methodology of 5G-Advanced Integrated Sensing and Communication”, June 2023.
R1-2400573, Discussion on ISAC channel model, Xiaomi, BUPT, February 26th – March 1st, 2024.
R1-2400899, Considerations on ISAC channel modelling, 3GPP RAN1#116, CAICT, Feb. 2024.
R1-2403160, Considerations on ISAC channel modelling, 3GPP RAN1#116b, CAICT, April 2024.
R1-2404724, Considerations on ISAC channel modelling, 3GPP RAN1#116b, CAICT, May 2024.
R1- 2406897, Considerations on ISAC channel modelling, 3GPP RAN1#118, CAICT, August 2024.
R1-2408810, Considerations on ISAC channel modelling, 3GPP RAN1#118bis, CAICT, October 2024.
R1-2410370, Considerations on ISAC channel modelling, 3GPP RAN1#119, CAICT, Nov. 2024.
R1-2500892, Considerations on ISAC channel modelling, 3GPP RAN1#120, CAICT, Feb. 2025.

TDoc file conclusion not found

3GPP TSG RAN WG1 #120bis                                                                                R1-2503080
Wuhan, China, April 7th – 11th, 2025

Source:	OPPO
Title:	Study on ISAC channel modelling
Agenda Item:	9.7.2
Document for:	Discussion and Decision

Conclusions
This contribution is concluded with the following observations and proposals:
Proposal 1: The mono-static RCS (model-2) of a standing human body is dependent on both zenith angle and azimuth angle, and is modeled as 

.,,
with parameters defined as:

Proposal 2: Before RAN1 confirms the RAN1 #120 working assumption on absolute delay, RAN1 seeks for an agreement on a LOS scattering model with non-zero  being applied, in order to retain a modeling feature that has already been agreed.
Proposal 3: Rel-19 ISAC channel model can provide informational examples of specific micro-Doppler functions (e.g. functions in Table 1) for interested sensing targets. 
Proposal 4: Maximum speed and ratio of moving scatters depends on scenarios. 
Speed of 95%-100% moving scatters follows uniform distribution between 0 and 180km/h for UAV case 
Speed of 95%-100% moving scatters is 0 for indoor case 
Speed of 50% moving scatters is 3-60km/h and speed of remaining moving scatters is 0 for UMa/UMi.
Proposal 5: The power normalization in combining the target channel(s) and background channel is formulated as a linear programming problem, solved as following. 
The power normalization coefficient for the background channel is 
The power normalization coefficient for a target channel is 
where 
The value of  has two options
Option 1: , i.e., the power normalization includes both LOS and NLOS in background channel. The K-factor for the whole Tx-Rx channel may change after target channels join in. 
Option 2: , i.e., the power normalization includes NLOS in background channel but not LOS in background channel. The K-factor for the whole Tx-Rx channel remains unchanged after target channels join in.
 for  are power of K target channels between Tx and Rx for K targets.
  is the lower bound of power normalization coefficient for the background channel, to protect the background channel power from reducing to an unreasonable low value. 
Proposal 6: The mono-static background channel model for indoor scenario can be modeled with either of the following two options based on a general parameterized Gamma distribution  with PDF function :
Option 1:
The background channel is generated with N=3 reference points (virtual Rx’s). Each reference point is characterized by a 3D distance (d3D) and a LOS_ZOD direction from the mono-static Tx/Rx.
The 3D distance (d3D) follows:  (m).
The LOS_ZOD follows:.
Option 2:
The background channel is generated with N=3 reference points (virtual Rx’s). Each reference point is characterized by a 2D distance (d2D) from the mono-static Tx/Rx and a height.
The 2D distance (d2D) follows:.
The height (h) follows: .

3GPP TSG RAN WG1 #120bis			 R1-2503146
Wuhan, China, April 7th – 11th, 2025
Agenda item:	9.7.2
Source:	Moderator (Xiaomi)
Title:	Summary #5 on ISAC channel modelling
Document for:	Discussion/Decision
Highlight on issues for RAN1#121
RAN1 #121 is the last meeting for the study item, we target completion of all remaining issues. 
Physical object model
A*B1 for Bistatic RCS 
A*B1 for monostatic RCS for human with RCS model 2
Spatial consistency
Correlation among the multiple scattering points
3D/vertical correlation distance
Cases to support or not support spatial consistency
EO type-2, e.g.,
LOS condition determination
EO type-2 in background channel 
Power of specular reflection ray in NLOS condition
Reference TRs to generate target channel and target channel
LOS probability, pathloss, etc. for UAV related scenarios
Reference TRs considering RSU type UE
Power normalization of target channel and background channel 
Others
Link level channel model, if time allows
Angular correlation of RCS/XPR
Blockage model A/B
Doppler/micro-Doppler

Proposal
The values of the parameters to generate background channel for TRP monostatic and UE monostatic sensing for each sensing scenario are provided in the following table 
FFS parameter values for other scenarios (e.g. indoor factory)
Email discussion/approval checking the values after April meeting, including validation for newly agreed parameters
The email discussion includes all scenarios, TRP monostatic and UE monostatic
The email discussion includes how to merge results provided by companies

Agreement
For human as a sensing target with a single scattering point, the height of the scattering point is 1.5 m.

Agreement
In sensing scenario UMi, UMa, RMa, if the height of a scattering point of target is less than 1.5m, for pathloss calculation, down-selection one of the options below:
Option 4: use  in Table 7.4.1-1: Pathloss models in TR 38.901
Option 5: use hUT 1.5 m for pathloss calculation

Agreement
For sensing scenario UMi, UMa, RMa, UMi-AV, UMa-AV and RMa-AV, the height of a scattering point of a target is used to calculate the LOS probability and pathloss, regardless of the lower bound in the existing TRs that are referred to generate ISAC channel.
FFS for the case where the height of a scattering point of target is less than 1.5m in sensing scenario UMi, UMa, RMa


For email approval
[FL3] Proposal 4.2.1-1 
On the monostatic RCS of UAV of large size,
The values/pattern of component A*B1 are generated by the following parameters 

When  is in the range [0°,45° ] or [135°,180°], 
The standard deviation of component B2 is 2.50 dB


For email approval
[FL3] Proposal 4.2.3-1 
On the monostatic RCS of AGV with single scattering point,
The values/pattern of component A*B1 are generated by the following parameters 

When  is in the range [0°,30° ), 
The standard deviation of component B2 is 2.51 dB

3GPP TSG RAN WG1 #120bis			 R1-2503152
Wuhan, China, April 7th – 11th, 2025
Agenda item:	9.7.2
Source:	Moderator (Xiaomi)
Title:	Email summary on [Post-120bis-ISAC-02] 
Document for:	Discussion/Decision

Conclusion
The following two proposals are endorsed at Apr. 27
Proposal 3-1 
On the monostatic RCS of UAV of large size,
The values/pattern of component A*B1 are generated by the following parameters 

When  is in the range [0°,45° ] or [135°,180°], 
The standard deviation of component B2 is 2.50 dB

Proposal 4-1-rev2 
On the monostatic RCS of AGV with single scattering point,
The values/pattern of component A*B1 are generated by the following parameters 

When  is in the range [0°,30° ), 
The standard deviation of component B2 is 2.51 dB


The following three proposals are endorsed at Apr. 30

Proposal 2.1-1-rev3 
The values of the parameters to generate background channel for TRP monostatic sensing for each sensing scenario are provided in the following table 

Note 1: Distributions of height and distance of reference point are not subject to geographical constraints on UT given in TR 38.901 for the corresponding deployment scenario.
Note 2: The reference points for generating the TRP monostatic background channel have no mobility, i.e. 0 km/h.

Proposal 2.2-1-rev3 
The values of the parameters to generate background channel for UT monostatic sensing for the following sensing scenarios are provided in the following table 

Note 1: Distributions of height and distance of reference point are not subject to geographical constraints on TRP given in TR 38.901 for the corresponding deployment scenario.
Note 2: The reference points for generating the UT monostatic background channel has the same velocity as UT.
Note 3: In the UT monostatic sensing in UMa and UMi scenario, the ZOD offset should be set as 0


Proposal 2.2-2-rev1 
The values of the parameters to generate background channel for UT monostatic sensing for the following sensing scenarios are provided in the following table 

Note 1: Distributions of height and distance of reference point are not subject to geographical constraints on TRP given in TR 38.901 for the corresponding deployment scenario.
Note 2: The reference points for generating the UT monostatic background channel has the same velocity as UT.
Note 3: In the UT monostatic sensing in UMa and UMi scenario, the ZOD offset should be set as 0