3GPP TSG RAN WG1 #121	    R1-2503233
St Julian’s, Malta, May 19th – 23rd, 2025
Agenda Item:	9.5.1
Source:	Futurewei
Title:	Discussion of on-demand SSB SCell operation
Document for:	Discussion and decision 

Conclusions
This contribution presents Futurewei’s views on resolving outstanding issues for on-demand SSB SCell operation. The proposals build on recent agreements and aim to close remaining open points to facilitate timely standardization in Rel-19.
Proposal 1: If AO SSB is CD-SSB not located on the synchronization raster, the frequency location of on-demand SSB is the same as the frequency location of always-on SSB.

Observation 1: There is no strong motivation to support OD CD-SSB not on sync raster and AO NCD-SSB scenario.
Proposal 2: If OD CD-SSB not on sync raster is supported, OD CD-SSB and AO NCD-SSB should have the same frequency location.
Proposal 3: From RAN1 perspective all OD-SSB RRC parameters—frequency, SSB position, subcarrier spacing, physical cell ID, transmit power, and time domain position—may be configured as lists to enable fast and flexible selection.
Proposal 4: For Case #1, od-ssb-nrofBurst should not be configured, as deactivation would impair UE operation.
Proposal 5: For Case #2, when od-ssb-nrofBurst is configured, gNB should have the option to deactivate OD-SSB prior to completing the full N-burst transmission by issuing a MAC-CE.
Proposal 6: No additional deactivation mechanisms beyond those already agreed (MAC-CE, N bursts) are necessary.
Proposal 7: Do not support indication of time offset between always-on SSB and on-demand SSB.
 

3GPP TSG-RAN WG1 Meeting #121	R1-2503267
St Julian’s, Malta, May 19th – 23rd, 2025
 
Agenda Item:	9.5.1
Source:	Huawei, HiSilicon
Title:	On-demand SSB SCell operation for eNES
Document for:	Discussion and Decision

Conclusion
This paper discussed how to design on-demand SSB operation for SCell, with the following observations and proposals:
The presence of od-ssb-PositionsInBurst in the RRC configuration indicates that the SSB indices within OD-SSB burst are independently/separately configured from the SSB indices within AO-SSB burst.

For Case#1, the SSBs for SSB-RO mapping should be the union of all the SSB indices configured by multiple od-ssb-PositionsInBurst.
For Case#2, the SSBs for SSB-RO mapping should be the union of all the SSB indices configured by multiple od-ssb-PositionsInBurst and by ssb-PositionsInBurst.
The RO validation should be dynamic, i.e., based on the actual transmission of OD-SSB. 
To address the inter-cell interference issue, the rate-matching pattern on a Rel-19 NES cell is based on all of the candidate OD-SSBs, i.e., a series of od-ssb-PositionsInBurst with the periodicity is the minimum value among the configured periodicities.
For the case when the centre frequency locations of AO-SSB and OD-SSB are different, PBCH payload of OD-SSB can be known to the UE by configuration. 
The presence of od-ssb-PositionsInBurst in the RRC configuration indicates that the SSB indices within OD-SSB burst are independently/separately configured from the SSB indices within AO-SSB burst.
When a signal/channel is configured to be QCLed with an SSB index that is only present in OD-SSB, the signal/channel is QCLed with OD-SSB only.
UE expects that the QCLed RS can be transmitted after OD-SSB is applied.
RAN1 shall clarify whether an SSB-less SCell is interpreted as Case#1 or Case#2.

3GPP TSG RAN WG1 meeting #121		                                   R1-2503315
St Julian’s, Malta, May 19th – 23rd, 2025
Title: 	Discussion on on-demand SSB for NES 
Source: 	ZTE Corporation, Sanechips
Agenda item:	9.5.1
Document for:	Discussion and decision

Conclusion
In this contribution, we have the following observations and proposals:
Observation 1:	After the SCell is deactivated, the on-demand SSB triggered before the SCell is deactivated is not necessary and will cause additional power consumption.
Observation 2:	Using timer to implicitly indicate the value of N performs the same function as configuring N directly but introduces a large workload.
Observation 3:	Time-C2 allows the half frame index of OD-SSB and AO-SSB to be different.

Proposal 1:	Support the case where SSB indices within on-demand SSB burst can be subset of SSB indices within always-on SSB burst when the center frequency locations of always-on SSB and on-demand SSB are the same.
Proposal 2:	Option 4 and option 4a can be supported.
Proposal 3:	When the od-ssb-nrofBurst for an on-demand SSB is configured, the on-demand SSB can be deactivated via MAC CE.
Proposal 4:	Introducing timer to implicitly determine the value of N is not supported.
Proposal 5:	When the center frequency locations of AO-SSB and OD-SSB are different, there should be no restriction requiring that PBCH payload for the same SSB index (other than SFN index, half frame index) should be the same for AO-SSB and OD-SSB.
Proposal 6:	Introduce the on-demand SSB resource configuration information in existing CSI resource Configurations.
Proposal 7:	It is unnecessary to associate different CSI report types with the signaling method that indicating the on-demand SSB transmission
Proposal 8:	Beam failure detection based on OD-SSB is not supported.
Proposal 9:	Beam failure recovery based on OD-SSB is supported.

3GPP TSG RAN WG1 #121                                                                       R1-2503365
St Julian’s, Malta, May 19th – 23th, 2025

Source: 	vivo
Title:	Remaining issues on on-demand SSB Scell operation
Agenda Item:	9.5.1	
Document for:	Discussion and Decision

Conclusion
This contribution focuses on the discussion of on-demand SSB for SCell with the following observations and proposals: 
Observation 1: SSB is not used for BFD on Scell in legacy.

Proposal 1: When MAC CE is used for updating the transmission parameter of a transmitted OD-SSB for the cell, only the parameter of periodicity could be updated.
Proposal 2: For updating the transmission parameter of a transmitted OD-SSB for the cell, SSB occasions with larger periodicity are subset of the SSB occasions with shorter periodicity.
Proposal 3: MAC CE could be used for updating the transmission parameter of a transmitted OD-SSB in Scenario #2 and Scenario #2A.
Proposal 4: Do not support the case where always-on SSB is CD-SSB and not on a synchronization raster.
Proposal 5: Always-on SSB and on-demand SSB are located in the same BWP with the smallest bandwidth, and the center frequency gap between always-on SSB and on-demand SSB are smaller than a pre-defined threshold.
Proposal 6: For the case when the center frequency locations of always-on SSB and on-demand SSB are different, other than SFN index, half frame index,  and pdcch-ConfigSIB1 could also be different between always-on SSB and on-demand SSB in PBCH payload for the same SSB index.
Proposal 7：For the case when the center frequency locations of always-on SSB and on-demand SSB are same，the half frame index of AO-SSB and OD-SSB should be same in Alt Time C1 and could be different in Alt Time-C2.
Proposal 9: Support Option 4 and 4a for Case #1 in addition to Option 2.
Proposal 10: A nonnumerical indication of N indicates that on-demand SSB transmission is deactivated along with the deactivation of SCell.
Proposal 11: Do not support that the value of N can be implicitly determined using a timer.
Proposal 12: MAC CE could be used to deactivate the on-demand SSB if od-ssb-nrofBurst for an on-demand SSB is configured.
Proposal 13: The time offset between always-on SSB and on-demand SSB is not introduced.
Proposal 14: The parameter list includes the following parameters:
SFN offset
Half frame index
Proposal 15: If the higher layer timeRestrictionForChannelMeasurements in CSI-ReportConfig is set to “Configured”, UE should measure only the most recent, no later than the CSI reference resource, occasion between OD-SSB occasion and AO-SSB occasion.
Proposal 16: To distinguish whether AO-SSB or OD-SSB is associated with a CSI report configuration, indicate the SSB type in the resource config associated with the CSI report configuration. 
Proposal 17: Semi-persistent and aperiodic CSI report configuration can be associated with any kind of SSB.
Proposal 18: Periodic CSI report configuration can only be associated with on-demand SSB that is activated through RRC signalling and will be deactivated along with the deactivation of SCell.
Proposal 19: Do not support on-demand SSB for LTM.
Proposal 20: To support on-demand SSB operation, prioritize the on-demand SSB transmission if there is collision between on-demand SSB and other transmission.
Proposal 21: Do not support on-demand SSB for BFD on Scell.

3GPP TSG RAN WG1 #121		R1-2503412
St Julian’s, Malta, May 19th – 23rd, 2025

Agenda item:		9.5.1
Source:	Nokia, Nokia Shanghai Bell
Title:	On-demand SSB SCell Operation
Document for:		Discussion and Decision

Conclusions
In this contribution, we have the following observations and proposals:
Proposal 1: OD-SSB transmitted as CD-SSB located on sync-raster is supported in Case#1.
Proposal 2: In Case#2, SSB indices of on-demand SSB burst are subset of SSB indices of always-on SSB burst.
Proposal 3: The periodicity of OD-SSB cannot be configured to be larger than the periodicity of always-on SSB.
Observation 1: For simplification of the options and progress towards a feasible solution, we can deprioritize the case when always-on SSB is CD-SSB not in the synchronization raster.
Proposal 4: For Case#2, when AO-SSB and OD-SSB are on different frequencies, PBCH payload for same SSB index shall be different due to the k_SSB contents.
Proposal 5: The od-ssb-config is cell-specific configuration.
Proposal 6: RAN1 to remove the od-ssb-physCellId from the OD-SSB configuration parameter list to avoid ambiguity. This parameter is already provided for every SCell during SCell addition.
Proposal 7: Besides MAC CE based and configured number of bursts-based deactivation, no other options are specified for OD-SSB deactivation.
Proposal 8: If od-ssb-nrofBurst for an on-demand SSB is configured, the on-demand SSB can be deactivated via MAC CE.
Proposal 9: MAC CE indication of OD-SSB transmission overrides potentially ongoing OD-SSB SSB transmission on the SCell.
Observation 2: The CSI resources are associated with a DL BWP. As per the current specification, the csi-SSB-ResourceList is the list of SSB-Index values which identify an SS-Block within the SSB burst. We do not see the need to modify the Resource setting.
Proposal 10: RAN1 to confirm that no additional signaling is required to indicate that CSI-report is associated with OD-SSB only.
Proposal 11: CSI report configuration can be associated with on-demand SSB regardless of signaling mechanism for indicating OD-SSB transmission
Proposal 12: For OD-SSB where od-ssb-nrOfBurst parameter is configured, only aperiodic CSI-reporting shall be configured. Otherwise, the reportConfigType shall be periodic, semi-persistent or aperiodic.
Proposal 13: On-demand SSB work is intended to enhance SCell operation, and we propose to keep mobility measurements and LTM out of scope of on-demand SSB.
Proposal 14: PDCSH rate matching around OD-SSB is supported.
Proposal 15: Consider the text proposal to update requirements in Chapter 10 of TS38.213 for interaction with OD-SSB and PDCCH monitoring.
Observation 3: For Case#1, RACH configuration may not be provided to the UE as AO-SSB is not configured. 
Proposal 16: For Case#2, the SSB to RO mapping is based on the ssb-PositionsInBurst defined for always-on SSB. For Case#1, if necessary, ssb-perRACH-Occasion kind of parameter needs to be configured for the OD-SSB. RAN1 should discuss the necessity of providing such configuration.
Proposal 17: Consider the text proposal to improve the RAN1 requirements in Chapter 4.4 of TS38.213
---------------------------------------------------- Start of the TP for TS38.213-------------------------------------------
A UE can be configured with [one or more] [od-ssb-config] [12, TS 38.331] for transmission of SS/PBCH blocks in a configured DL BWP of an SCell and a [od-ssb-config] is associated with a [configuration-index]. A UE can be indicated, by [od-ssb-config] [12, TS 38.331] by a higher layer parameter or by a [first] MAC CE [11, TS 38.321], activation of transmission for SS/PBCH blocks in a configured DL BWP of an SCell [19, TS 38.300]. The UE can also be indicated, by a [configuration-index] provided via [third] MAC CE activation of transmission for SS/PBCH blocks or adaptation of parameters for the activated transmission of SS/PBCH blocks when the SCell is activated. A number of half frames with transmission of SS/PBCH blocks is indicated by the [first or third] MAC CE from values provided by od-ssb-nrofBurst, if provided; otherwise, the transmission of the SS/PBCH blocks occurs until it is deactivated by a [second] MAC CE [11, TS 38.321], 
The parameters for transmission of SS/PBCH blocks are provided within od-ssb-config where 
-     the physical cell identity of the SS/PBCH blocks is indicated by od-ssb-physCellId, if provided; otherwise, by ssb-physCellId in ServingCellConfigCommon 
-	the indexes of transmitted SS/PBCH blocks are indicated by the [first or the third] MAC CE from candidate values provided by od-ssb-PositionsInBurst, if provided; otherwise, by ssb-PositionsInBurst 
-	the frequency location of the SS/PBCH blocks is indicated by od-absoluteFrequencySSB, if provided; otherwise, by absoluteFrequencySSB 
-	the SCS configuration of the SS/PBCH blocks is indicated by od-ssbSubcarrierSpacing, if provided; otherwise, by ssbSubcarrierSpacing
-	the power of the SS/PBCH blocks is indicated by od-ss-PBCH-BlockPower, if provided; otherwise, by ss-PBCH-BlockPower 
-	the periodicity of the transmission of the SS/PBCH blocks are indicated by the [first or third] MAC CE from candidate values by od-ssb-Periodicity
-	the half frames for the transmission of the SS/PBCH blocks are determined based on an indication by the [first or third] MAC CE 
-	the transmission of the SS/PBCH blocks is in frames with SFN determined from , where  is the periodicity for the transmission of the SS/PBCH blocks, and  is the indicated SFN offset by the [first or third] MAC CE from candidate values by od-ssb-sfn-Offset, if provided; else, . An index of a half frame with transmission of the SS/PBCH blocks in a corresponding frame is indicated by the [first or third] MAC CE from candidate values by od-ssb- halfFrameIndex, if provided; else the index is 0
When the activation or adaptation of the SS/PBCH blocks transmission is by the [first or the third] MAC CE, respectively, [and with reference to slots of a configured DL BWP for the SS/PBCH blocks transmission,] the UE expects that the transmission of the SS/PBCH blocks according to the indicated parameters starts from a first slot including the candidate SS/PBCH block occasion corresponding to the first transmitted SS/PBCH block index and located in a first half frame within the half frames for the transmissions of the SS/PBCH blocks, that is at least  slots after slot , where  is a slot when a PDSCH reception providing the [first or the third] MAC CE ends, respectively,  is a slot indicated for PUCCH transmission with HARQ-ACK information for the PDSCH reception as described in clause 9.2.3, and  is a number of slots per subframe for the SCS configuration  of the PUCCH transmission as defined in [4, TS 38.211].
When the activation of transmission for the SS/PBCH blocks is by od-ssb-config, the UE expects that the transmission of the SS/PBCH blocks [starts at the next half frame with transmission of the SS/PBCH blocks]. 
When the deactivation of the SS/PBCH blocks transmission is indicated by the [second] MAC CE, [and with reference to slots of the configured DL BWP for the SS/PBCH blocks transmission,] the UE expects that the transmission of the SS/PBCH blocks according to the indicated parameters terminates from  
-	a slot , if the slot  is not within a first slot to a last slot with activated transmission of SS/PBCH blocks in a half frame, where ,  is a slot when a PDSCH reception providing the [second] MAC CE ends,  is a slot indicated for PUCCH transmission with HARQ-ACK information for the PDSCH reception as described in clause 9.2.3, and  is a number of slots per subframe for the SCS configuration  of the PUCCH transmission as defined in [4, TS 38.211]
-	the first slot including the candidate SS/PBCH block corresponding to the last transmitted SS/PBCH block index that is not earlier than the slot , if the slot  is within a first slot to a last slot with activated transmission of SS/PBCH blocks in a half frame
---------------------------------------------------- End of the TP for TS38.213-------------------------------------------

3GPP TSG RAN1#121 Meeting	R1-2503416
St Julians, Malta, May 19th – 23rd, 2025
Agenda item:	9.5.1
Source:	NEC
Title:	Discussion on on-demand SSB for SCell operation
Document for:	Discussion 

Conclusion
From the discussion, we have the following proposals:
Proposal 1: When on-demand SSB is transmitting periodically, NES cell can be used as an SCell for non-NES UEs irrespective of whether on-demand SSB is CD-SSB.
Proposal 2: At least for case#1, on-demand SSB can be CD-SSB and transmitted on synch-raster with assumption the network ensures periodic CD-SSB transmission when NES cell is activated for any UE.
Proposal 3: Support on-demand SSB indication via group-common DCI for Scenario#2 and Scenario#3.
Proposal 4: On-demand SSB for SCell may be enabled via DCI format 1_x on PCell with a carrier indication field to indicate the applicable carrier.
Proposal 5: The UE may assume that the set of SSB indices configured within od-ssb-PositionsInBurst for on-demand SSB is a subset of, or identical to, the set of SSB indices configured within ssb-PositionsInBurst for always-on SSB on the same cell.
Proposal 6: For Case#2, when an on-demand SSB transmission occasion overlaps in the time domain with an always-on SSB transmission occasion, the UE may expect the transmission to follow the parameters (including transmitted SSB indices defined by ssb-PositionsInBurst) of the always-on SSB.
Proposal 7: For Case #2, when AO-SSB and OD-SSB share the same centre frequency, support half frame index for OD-SSB to be the same as or different from the half-frame index associated with AO-SSB.
Proposal 8: For Case #2, when AO-SSB and OD-SSB have different centre frequencies:
Confirm that the MIB parameters k_SSB (ssb-SubcarrierOffset), pdcch-ConfigSIB1, and halfFrameIndex for OD-SSB can be different than those of AO-SSB.
Agree that other MIB parameters (dmrs-TypeA-Position, subCarrierSpacingCommon, cellBarred, intraFreqReselection) for OD-SSB are the same as those broadcast in the PBCH of the AO-SSB.
Proposal 9: UE expects that on-demand SSB indication is received and UE can measure on-demand SSB before UE transmits a CSI report corresponding to a CSI reporting configuration associated with on-demand SSB.
Proposal 10: Before SCell activation, UE expects that gNB configures one of on-demand SSB or always-on SSB for all configured periodic SSB measurements.
Proposal 11: For Case #2, after SCell activation, down-select one of the following alternatives regarding OD-SSB measurements and link recovery:
Alternative 1: UE relies on periodic measurements of always-on SSB for SCell link monitoring/recovery procedures. UE measurements based on OD-SSB (when configured) are restricted to aperiodic reporting types.
Alternative 2: Support using on-demand SSB for SCell link recovery procedures.
Proposal 12: For aperiodic CSI reporting based on on-demand SSB consider one of the following options:
-Option-1: Support group-common based DCI indication for on-demand SSB indication
-Option-2: Support indication of on-demand SSB within the CSI report trigger indication 
Proposal 13: Upon failure to receive or detect the on-demand SSB, the UE may indicate on-demand SSB failure indication to the network. Following options can be considered for the indication 
Option-1: RRC signaling
Option-2: MAC CE
Option-3: UCI transmitted over PCell
Proposal 14: Address PDSCH rate matching around on-demand SSB indicated to other UE of the NES cell as well as on-demand SSB indicated to the UE, and discuss whether common or dedicated signaling is used

3GPP TSG RAN WG1 #121		                        R1-2503519
Saint Julian, Malta, May 19th – 23th, 2025
Agenda Item:	9.5.1
Source:	Spreadtrum, UNISOC
Title: 	Discussion on on-demand SSB SCell operation
Document for:	Discussion and decision

Conclusion
We have the following observations and proposals.
For the case when AO-SSB is CD-SSB and not on a synchronization raster, the frequency location of OD-SSB and AO-SSB subject to network configuration.
If od-ssb-nrofBurst for an on-demand SSB is configured, the on-demand SSB is deactivated based on the configured value for od-ssb-nrofBurst or via MAC CE.
It is up to UE to measure both SSBs or one of them if the higher layer timeRestrictionForChannelMeasurements in CSI-ReportConfig is set to “notConfigured”.

3GPP TSG RAN WG1 #121                                                                                R1-2503539               
St Julian's, Malta, May 19th-23rd, 2025

Source:	TCL
Title:	Discussion on on-demand SSB Scell operation for NES
Agenda Item:	9.5.1
Document for:	Discussion and Decision

Conclusion
This paper discussed how to design on-demand SSB Scell operation, with the following observation/proposals:
Observation 1: Even if most cases consider semi static-based MAC CE to indicate OD-SSB transmission,  but specific DCI could be used for reducing signaling overhead if multiple UE configured with same SCell, e.g., group common DCI. 

Observation 2: In RAN  1#120 meeting, DCI format 2_9 as group common DCI has been agreed for the indication of periodicity adaptation of  SSB.

Observation 3: One restriction is whether overlapping happened between two different OD-SSB transmission if same center frequency is assumed for these two OD-SSB.


Proposal 1: Support at least group common DCI used for indicating OD-SSB transmission.

Proposal 2: Consider how to avoid overlap of time domain or frequency domain between multiple OD-SSB transmissions.

Proposal 3: Support define reference point of OD-SSB for case #2 based on periodicity of AO-SSB.

Proposal 4: Consider how to handle collision between OD-SSB and AO-SSB, including priority definition or following previous type of SSB to receive SSB when collision happened.

Proposal 5: Discussion on the impact of OD-SSB transmission including case #1 and case #2 on BFD reporting periodicity or detection timer.

Proposal 6: Discuss how to handle collision between OD-SSB resource and NR resource and how to handle rate-matching.

3GPP TSG RAN WG1 #121		R1-2503570
St Julian's, Malta, 19th – 23rd May, 2025
Agenda item:	9.5.1
Source:	Samsung
Title:	On-demand SSB SCell operation
Document for:	Discussion and Decision

Conclusion
The proposals from this contribution are summarized below: 
Proposal 1: For on-demand SSB:
Support a list of configurations by RRC, wherein each configuration includes the following parameters: 
od-ssb-Periodicity; 
od-ssb-sfn-Offset; 
od-ssb-halfFrameIndex; 
od-ssb-PositionsInBurst; 
od-ssb-nrofBurst.
Note: some parameter(s) can be optional subject to RAN1 agreements. 
The maximum number of configurations in the list is 16. 
Proposal 2: When on-demand SSB transmission is indicated to be activated by the RRC, the UE applies the parameters associated with the first configuration within the list of configurations included the RRC for the on-demand SSB transmission. 
Need to specify the timeline at least when the number of transmitted on-demand SSB bursts is provided.
Proposal 3: For adaptation of parameter(s) for on-demand SSB, support all the following cases: 
Case A1: activation by a RRC and N is not provided + adaptation by a MAC CE;
Case A2: activation by a RRC and N is provided + adaptation by a MAC CE;
Case B1: activation by a MAC CE and N is not provided + adaptation by a MAC CE;
Case B2: activation by a MAC CE and N is provided + adaptation by a MAC CE.
Proposal 4: For deactivation for on-demand SSB, support all the following cases: 
Case X1: activation by a RRC and N is not provided + deactivation by a MAC CE;
Case X2: activation by a RRC and N is provided + deactivation after N transmission bursts;
Case X3: activation by a RRC and N is provided + deactivation by a MAC CE;
Case Y1: activation by a MAC CE and N is not provided + deactivation by another MAC CE;
Case Y2: activation by a MAC CE and N is provided + deactivation after N transmission bursts;
Case Y3: activation by a MAC CE and N is provided + deactivation by another MAC CE;
Case Z1: adaptation by a MAC CE and N is not provided + deactivation by another MAC CE;
Case Z2: adaptation by a MAC CE and N is provided + deactivation after N transmission bursts;
Case Z3: adaptation by a MAC CE and N is provided + deactivation by another MAC CE.
Proposal 5: For the case when the center frequency locations of always-on SSB and on-demand SSB are different: 
On-demand SSB is a NCD-SSB;
Transmitted SSB indexes for on-demand SSB are same as or a subset of the ones for always-on SSB.
Proposal 6: For Case 2 (i.e., with always-on SSB), only when always-on SSB and on-demand SSB have different center frequencies, a CSI report configuration is associated with on-demand SSB only. 
Proposal 7: For L1 measurement based on on-demand SSB: 
Before on-demand SSB is indicated to be transmitted, the UE is not required to perform L1 measurement or CSI reporting even though it receives the configuration on L1 measurement and reporting; 
When on-demand SSB is indicated to be transmitted in Scenario #2, the UE can be required to perform CSI reporting in Scenario #2. 
Proposal 8: 
For UEs knowing the time and frequency resources of on-demand SSB, the same procedures for resource allocation (e.g., PDCCH, and PDSCH) and validation (e.g., PRACH, and PUSCH) based on always-on SSB can be reused for on-demand SSB.
For UEs not knowing the time and frequency resources of on-demand SSB, it is up to gNB implementation to handle resource allocation and validation based on always-on SSB.
RateMatchPattern needs enhancement to cover the time and frequency resources of on-demand SSB.
Proposal 9: Support uplink power control based on on-demand SSB, and similar approach to L1 measurement based on on-demand SSB can be used. 

3GPP TSG RAN WG1 #121          					                R1-2503718
St Julian's, Malta, May 19th – 23rd, 2025
Source:	Tejas Networks Ltd
Title:	On demand SSB SCell operation for NES
Agenda item:	9.5.1	
Document for:	Discussion and Decision

Conclusions

 For the case when the centre frequency locations of always-on SSB(AO-SSB) and on-demand SSB(OD-SSB) are same, half frame index can be same or different for AO-SSB and OD-SSB.

 For the case when the center frequency locations of always-on SSB and on-demand SSB are different, the PBCH payload for AO-SSB and OD-SSB can be same or different.

Periodicity of OD-SSB burst periodicity can be independent of AO-SSB periodicity.

Supporting Mux-Case #1: No time-domain overlap between always-on SSB and on-demand SSB.

Collision handling of OD-SSB with other channels should be discussed.

3GPP TSG RAN WG1 #121	R1-2503737
St Julian’s, Malta, May 19th – May 23rd, 2025

Agenda item:		9.5.1
Source:				Ofinno
Title:					Discussion on on-demand SSB SCell operation
Document for:		Discussion and Decision

Conclusion
This contribution has discussed the remaining issues related to the on-demand SSB SCell operation. The following are our proposals: 
Proposal 1: RAN1 to agree “The periodicity of OD-SSB is equal to or smaller than that of AO-SSB in Case #2”.
Proposal 2: For the case when frequency locations of AO-SSB and OD-SSB are the same, the half frame index can be the same or different for AO-SSB and OD-SSB.
Proposal 3: For the case when frequency locations of AO-SSB and OD-SSB are different, PBCH payload for the same SSB index (other than SFN index, half frame index) does not have to be the same for AO-SSB and OD-SSB.
Proposal 4: We propose the following changes to the previous agreement as follows:
Regarding the relation in terms of frequency location (i.e., center frequency) between the always-on SSB and on-demand SSB,
Alt 1: If always-on SSB is CD-SSB on a synchronization raster, the frequency location of on-demand SSB is different from the frequency location of always-on SSB.
On-demand SSB is not on sync raster
Active AO-SSB and OD-SSB are located in an active the same BWP
OD-SSB is NCD-SSB
FFS: Additional conditions
Subject to separate UE capability
Note: UE is not required to measure both AO-SSB and OD-SSB
Proposal 5: Other potential conditions are left for RAN4 to decide, e.g., intra-frequency measurement.
Proposal 6: There is no strong motivation to support OD-SSB for CD-SSB is located on sync-raster. If supported, then proper restriction should be studied to minimize the impact on the UE initial cell search.
Proposal 7: DCI based signaling to indicate on-demand SSB transmission on the cell is not supported.
Proposal 8: The time offset between OD-SSB and AO-SSB is indicated by using similar parameter (e.g., ssb-TimeOffset) used for indicating the time offset between CD-SSB and the NCD-SSB.
Proposal 9: No additional restriction is needed when multiple candidate values of the OD-SSB burst (i.e., od-ssb-PositionsInBurst) and the number of OD-SSB bursts (i.e., od-ssb- nrofBurst) are configured via RRC signaling.
Proposal 10: We support that the configuration of the OD-SSB is cell specific.
Proposal 11: If od-ssb-nrofBurst for an on-demand SSB is configured and the SCell is deactivated (e.g., via MAC-CE) then the UE shall assume that the on-demand SSB is deactivated upon the deactivation of the SCell.
Proposal 12: Regarding “FFS: It is up to UE to measure both SSBs or one of them if the higher layer timeRestrictionForChannelMeasurements in CSI-ReportConfig is set to “Configured”., we propose not to agree. 
Proposal 13: CSI measurement associated only with the OD-SSB can be configured for both same and different frequencies of AO-SSB and OD-SS in Case #2. 
Proposal 14: Periodic, aperiodic and semi-persistent reporting of the L1 measurements on OD-SSB are supported.
Proposal 15: For a CSI report configuration configured with reportConfigType set to periodic, Alt 2 is supported:
Alt 2: The CSI report configuration can be associated with on-demand SSB regardless of signaling mechanism for indicating OD-SSB transmission.
Proposal 16: Do not define UE behavior on L1 measurement for on-demand SSB before on-demand SSB is indicated to be transmitted or after on-demand SSB transmission is deactivated. .
Proposal 17: The beam failure detection (BFD) based on OD-SSB is supported in Case # 1 and Case # 2.
Proposal 18: The candidate beam detection (CBD) based on OD-SSB is supported in Case # 1 and Case # 2.
Proposal 19: The UE does not expect that the OD-SSB is transmitted when OD-SSB overlaps with AO-SSB in time and frequency domains.
Proposal 20: Rate matching on OD-SSB should consider active OD-SSB transmission for the UE, potential OD-SSB transmission to other UE(s), and optionally non-serving cell.
Proposal 21: PRACH occasion and/or PUSCH occasion may be determined based on OD-SSB in Case #1. PRACH occasion and/or PUSCH occasion are determined only based on AO-SSB in Case #2. 
Proposal 22: TCI state/PL-RS: in case TCI state has OD-SSB as RS source in Case # 2 and OD-SSB is deactivated, then UE fallbacks to QCL-ed AO-SSB.
Proposal 23: Support OD-SSB as a PL fallback in Case #1. 

3GPP TSG RAN WG1 #121                                                                                  R1-2503797
St Julian’s, Malta, May 19th – 23rd, 2025

Source:	CATT
Title:	Discussion on on-demand SSB SCell operation
Agenda Item:	9.5.1
Document for:	Discussion and Decision

Conclusion
In this contribution, we discuss on-demand SSB SCell operation, and give the following observations and proposals:
Observation 1: Since the new MAC CE for OD-SSB transmission indication and the legacy MAC CE for SCell activation/deactivation are two independent MAC CEs, the gNB can trigger OD-SSB when needed via the new MAC CE, irrespective of the timing relationship with SCell activation/deactivation.
Observation 2: In order to support scenario 2A, the new MAC CE for OD-SSB transmission indication and the legacy MAC CE for SCell activation/deactivation can be sent together in one PDSCH.
Observation 3: The motivation of supporting OD-SSB for CD-SSB located on sync-raster is not clear.
Proposal 1: It is up to gNB implementation when OD-SSB is triggered, irrespective of the timing relationship with SCell activation/deactivation.
Proposal 2: Deprioritize the discussion of additional support of OD-SSB for CD-SSB located on sync-raster in Rel-19.
Proposal 3: Deprioritize the discussion of LTM based on on-demand SSB in Rel-19.
Proposal 4: Consider two candidate solutions to add on-demand SSB resource configuration to existing CSI resource configuration.
Alt-1: The existing IE CSI-ResourceConfig should include the on-demand SSB resource configuration information.
Alt-2: A new dedicated resource configuration IE for on-demand SSB resource configuration should be introduced, e.g. CSI-ResourceConfig-NES.
Proposal 5: For a cell supporting on-demand SSB SCell operation and for Case #2 (i.e., always-on SSB is periodically transmitted on the cell), when a CSI report configuration is associated with both AO-SSB and OD-SSB: 
It should apply for the case where AO-SSB and OD-SSB have the same center frequency and should not apply for the case where AO-SSB and OD-SSB have the different center frequencies. 
In this case, the UE shall derive the channel measurements for computing L1-RSRP/L1-SINR reported in uplink slot n based on only the most recent occasion of SS/PBCH associated with the CSI resource setting, and the occasion is no later than the CSI reference resource, if the higher layer timeRestrictionForChannelMeasurements in CSI-ReportConfig is set to “Configured”.
Proposal 6: For a cell supporting on-demand SSB SCell operation and for Case #2 (i.e., always-on SSB is periodically transmitted on the cell), for a CSI report configuration is associated with OD-SSB only, in addition to the case where AO-SSB and OD-SSB have the different center frequencies, it should apply for the case where AO-SSB and OD-SSB have the same center frequency as well.
Proposal 7: In order to support a CSI report configuration being associated with both of AO-SSB and OD-SSB or OD-SSB only using a single CSI-ReportConfig IE for Case #2 (i.e., always-on SSB is periodically transmitted on the cell), the reporting configuration for AO-SSB in the CSI-ReportConfig IE should be optional.
Proposal 8: It is up to gNB implementation whether OD-SSB and always-on SSB have same beam or not.
Proposal 9: Consider two candidate solutions to add on-demand SSB reporting configuration to existing CSI reporting configuration.
Alt-1: The existing IE CSI-ReportConfig should include the on-demand SSB reporting configuration information.
Alt-2: A new dedicated reporting configuration IE for on-demand SSB reporting configuration should be introduced, e.g. CSI-ReportConfig-NES.
Proposal 10: Consider two candidate solutions to activate and deactivate semi-persistent L1 measurement reporting on PUCCH for on-demand SSB.
Alt-1: The existing SP CSI reporting on PUCCH Activation/Deactivation MAC CE should include the activation and deactivation of SP CSI reporting on PUCCH for on-demand SSB, e.g., one of the reserved bits can be used to indicate whether the MAC CE applies to SP CSI reporting on PUCCH Activation/Deactivation for on-demand SSB or not.
Alt-2: A new dedicated MAC CE should be introduced for activation and deactivation of semi-persistent L1 measurement reporting on PUCCH for on-demand SSB.
Proposal 11: Consider two candidate solutions to trigger semi-persistent L1 measurement reporting on PUSCH for on-demand SSB.
Alt-1: The existing DCI field CSI request is reused to trigger semi-persistent L1 measurement reporting on PUSCH for on-demand SSB, and the existing DCI field Transform precoding indicator is used to indicate the DCI is used to trigger semi-persistent L1 measurement reporting on PUSCH for on-demand SSB, or for legacy MIMO/LTM.
Alt-2: A new dedicated RNTI (e.g., OD-SSB-SP-Reporting-RNTI) for DCI format 0_1 and 0_2 should be introduced for triggering of semi-persistent L1 measurement reporting on PUSCH for on-demand SSB.
Proposal 12: Consider two candidate solutions to support the semi-persistent L1 measurement reporting on PUSCH for multiple on-demand SSBs from multiple SCells.
Alt-1: The existing IE CSI-SemiPersistentOnPUSCH-TriggerState should include multiple CSI-ReportConfigIds. Each CSI-ReportConfigId is associated with one on-demand SSB resource configuration information.
Alt-2: A new dedicated trigger state IE for on-demand SSB should be introduced, e.g. CSI-SemiPersistentOnPUSCH-TriggerState-NES.
Proposal 13: Consider the following solution to trigger aperiodic L1 measurement reporting on PUSCH for on-demand SSB.
A new dedicated RNTI (e.g., OD-SSB-Aperiodic-Reporting-RNTI) for DCI format 0_1 and 0_2 should be introduced for triggering of aperiodic L1 measurement reporting on PUSCH for on-demand SSB.
Proposal 14: A unified group-common DCI could be designed to indicate on-demand SSB transmission.
Proposal 15: Support the following options for OD-SSB deactivation: 
Option 4: On-demand SSB transmission, if any, is deactivated when UE receives SCell deactivation MAC-CE for the activated SCell.
Option 4A: On-demand SSB transmission, if any, is deactivated when the timer for SCell deactivation is expired.
Proposal 16: If od-ssb-nrofBurst for an on-demand SSB is configured, the on-demand SSB is deactivated based on the configured value for od-ssb-nrofBurst or via MAC CE. 
Proposal 17: On-demand SSB configuration is cell-specific.
Proposal 18: Regarding the relation in terms of periodicity between always-on SSB and OD-SSB, the periodicity of on-demand SSB should be equal to or smaller than that of always-on SSB.
Proposal 19: For the case when the center frequency locations of always-on SSB and on-demand SSB are the same, half frame index should be the same for AO-SSB and OD-SSB.
Proposal 20: For the case when the center frequency locations of always-on SSB and on-demand SSB are different, it is up to the gNB implementation whether PBCH payload for the same SSB index (other than SFN index, half frame index) is the same or different for AO-SSB and OD-SSB.
Proposal 21: There is no need to introduce additional conditions for the following Alt 1 in the agreement in RAN1#120:
Alt 1: If always-on SSB is CD-SSB on a synchronization raster, the frequency location of on-demand SSB is different from the frequency location of always-on SSB.
On-demand SSB is not on sync raster
AO-SSB and OD-SSB are located in the same BWP
Subject to separate UE capability
Note: UE is not required to measure both AO-SSB and OD-SSB

Proposal 22: RAN1 should clarify the meaning of the note: UE is not required to measure both AO-SSB and OD-SSB in the agreement in RAN1#120.
Possible meaning Alt-1: the UE is not required to measure both AO-SSB and OD-SSB after UE received RRC or MAC CE based signaling indicating OD-SSB transmission.
Possible meaning Alt-2: the UE is not required to measure both AO-SSB and OD-SSB during the actual transmission of OD-SSB.
Proposal 23: The following Alt A in the agreement in RAN1#119 should be supported.
Alt A: If always-on SSB is CD-SSB and not on a synchronization raster, the frequency location of on-demand SSB can be same or different from the frequency location of always-on SSB, subject to its configuration. 
Proposal 24: Regarding the spatial relation between the always-on SSB and OD-SSB, it is up to the gNB implementation whether SSB indices within the on-demand SSB burst are a subset of or not a subset of the SSB indices within always-on SSB burst.
Proposal 25: Both Mux-Case #1 and Mux-Case #2 in the agreement in RAN1#118-bis should be supported in Rel-19.
If always-on SSB and on-demand SSB overlap in both time domain and frequency domain, always-on SSB should be prioritized over on-demand SSB to avoid the collision between always-on SSB and on-demand SSB.
Proposal 26: Rate-matching issue needs to consider on-demand SSB transmission of both serving cell and neighboring cell.
Proposal 27: For parameter change, an on-demand SSB transmission indication for an SCell could override a potentially ongoing on-demand SSB transmission for that SCell. For the other cases, the ongoing on-demand SSB should not be impacted by an on-demand SSB transmission indication.

3GPP TSG RAN WG1 #121																      R1-2503835
Malta, MT, May 19th–May 23th, 2025

Source: 	CMCC
Title:	Discussion on on-demand SSB SCell operation
Agenda item:	9.5.1
Document for:	Discussion & Decision

Conclusion
In this contribution, we discussed the configuration parameters, L1 measurement and collision handling of on-demand SSB in SCell for connected UEs, and the following proposals are made.
Proposal 1: For the remaining issues in deactivation mechanism, support:
Up to RAN4 to determine the specific value of N2.
If od-ssb-nrofBurst is configured, the on-demand SSB deactivation based on value for od-ssb-nrofBurst is a baseline and the MAC CE based deactivation can be the enhancement on top of it.

Proposal 2: For a cell supporting on-demand SSB SCell operation, at least for the following parameter(s), multiple candidate values can be configured by RRC and the applicable value can be indicated by MAC CE for on-demand SSB transmission indication for the cell.
Periodicity of the on-demand SSB (i.e., od-ssb-Periodicity)
Time location of on-demand SSB burst (i.e., od-ssb-sfn-Offset and od-ssb-halfFrameIndex)

Proposal 3: For a cell supporting on-demand SSB SCell operation, at least for the following parameter(s), one candidate value is configured by RRC, and is applicable for multiple OD-SSB configuration, if any.
Frequency of the on-demand SSB (i.e., od-ssb-absoluteFrequency)
Sub-carrier spacing of the on-demand SSB (i.e., od-ssbSubcarrierSpacing) for Case #1
Physical Cell ID of the on-demand SSB (i.e., od-ssb-physCellId) for Case #1
Downlink transmit power of on-demand SSB (i.e., od-ss-PBCH-BlockPower) for Case #1

Proposal 4: The case where always-on SSB is CD-SSB and not on a synchronization raster is not supported.

Proposal 5: When the center frequency locations of AO-SSB and OD-SSB are same, there is no need to restrict the half frame index to be same or different.

Proposal 6: When the center frequency locations of AO-SSB and OD-SSB are different, there is no need to restrict the PBCH payload for the same SSB index (other than SFN index, half frame index) to be same.

Proposal 7: Update the previous RAN1 agreement as follows.
Agreement
At least support L1 measurement based on on-demand SSB 
For L1 measurement based on on-demand SSB, periodic, semi-persistent, and aperiodic L1 measurement reports based on existing CSI framework are supported.
FFS on potential enhancements of CSI report configuration and/or triggering/activation mechanisms for L1 measurement based on on-demand SSB
The support of LTM is a separate discussion point

Proposal 8: RAN1 to further discuss the UE behavior with OD-SSB operation under the following procedures:
UE behavior on rate matching of PDSCH
UE behavior on PDCCH monitoring
UE behavior on UL (e.g. PUSCH, PUCCH, PRACH) transmission

Proposal 9: Use DCI 2_9 with CRC scrambled by ssbPeriodicityIndication-RNTI to indicate the transmission of OD-SSB for collision handling.
A new indication for the start position of OD-SSB indication in each information block can be introduced.

Proposal 10: Adopt the following update to Clause 10 of TS 38.213 for PDCCH monitoring.

Proposal 11: Adopt the following update to Clause 5.1.4 of TS 38.214 for PDSCH resource mapping.

Proposal 12: Adopt the following update to Clause 11.1 of TS 38.213 for UL transmission.

3GPP TSG RAN WG1 #121		                      R1- 2503886
St Julian’s, Malta, May 19th – 23rd, 2025

Agenda Item:	9.5.1
Source:	Xiaomi 
Title:                     Discussion on on-demand SSB SCell operation
Document for:	Decision

Conclusion

In this contribution, we discussed the procedures and signallings to support on-demand SSB and the impacts of on-demand SSB on UE behaviours were analysed. The proposes are summarized as following:

Proposal 1: On-demand SSB can be CD-SSB located on sync-raster.
Proposal 2: For other cases other than the following case, support RRC based signaling to indicate on-demand SSB transmission.
This RRC also configures the SCell, activates the SCell, and provides on-demand SSB configuration.
Proposal 3: For a SCell supporting on-demand SSB operation, Option 1 can be used to deactivate on-demand SSB transmission in the following scenarios
scenario #2 and scenario #2A with Case #1 and Case #2
scenario #3B and Case #2
Proposal 4: For a SCell supporting on-demand SSB operation, Option 4, 4A are not supported. 
Option 4: On-demand SSB transmission, if any, is deactivated when UE receives SCell deactivation MAC-CE for the activated SCell
Option 4A: On-demand SSB transmission, if any, is deactivated when the timer for SCell deactivation is expired
Proposal 5: For Case#2, the periodicity of on-demand SSB should be equal to or smaller than that of always-on SSB.
Proposal 6: For AO-SSB and OD-SSB with same SSB index, SFN index and half frame index can be same or different. In addition, the ssb-SubcarrierOffset should be different for OD-SSB and AO-SSB if their centre frequency is different. 
Proposal 7: SSB indices within on-demand SSB burst can be subset or same as that set of SSB indices within always-on SSB burst, which is subject to its configuration.
Proposal 8: UE should preclude measurement result associated to a SSB which is turned off by gNB.
Proposal 9: For a cell supporting on-demand SSB SCell operation and for Case #2 (i.e., Always-on SSB is periodically transmitted on the cell),
A CSI report configuration can be associated with 
both of AO-SSB and OD-SSB 
Applies for the case where AO-SSB and OD-SSB have the same/different center frequencies and the same positions in the same SSB burst 
It is up to UE to measure both SSBs or one of them if the higher layer timeRestrictionForChannelMeasurements in CSI-ReportConfig is set to “Configured”.
OD-SSB only
Applies for the case where AO-SSB and OD-SSB have the same/different center frequencies
Proposal 10: For a cell supporting on-demand SSB SCell operation and for L1 measurement based on on-demand SSB
For Scenario #2 (Case #1 & Case #2), Scenario #2A (Case #1 & Case #2), Scenario #3B (Case #1 & Case #2), semi-persistent and aperiodic CSI report are supported.
Proposal 11: Beam failure detection based on OD-SSB is not supported for Case #1 and Case #2.
Proposal 12: Beam failure recovery based on OD-SSB is supported for both Case #1 and Case #2.
Proposal 13: PDSCH is rate-matched around OD-SSB when OD-SSB is transmitted.

3GPP TSG RAN WG1 #121		                                       R1-2503972 
St Julian’s, Malta, May 19th – 23th, 2025

Agenda Item:	9.5.1
Source:	InterDigital Inc.
Title:	Discussion on on-demand SSB SCell operation
Document for:	Discussion 

Conclusion
In this contribution, the following proposals
Proposal 1: If od-ssb-nrofBurst for an OD-SSB is configured, support deactivation of OD-SSB based on the configured value for od-ssb-nrofBurst or via MAC CE 
Proposal 2: Support the UE to follow the last received MAC CE on OD-SSB (i.e. MAC CE containing the OD-SSB configuration index) to identify the number N of OD-SSB bursts
Proposal 3: If the higher layer timeRestrictionForChannelMeasurements in CSI-ReportConfig is set to “Configured”, the UE derives L1 measurement result based on one of AO-SSB or OD-SSB that is the most recent
Proposal 4: Support CSI report configuration associated with only OD-SSB at least when the center frequency locations of AO-SSB and OD-SSB are different  
Proposal 5: For the case when the center frequency locations of AO-SSB and OD-SSB are different, no restriction for the PBCH payload to be the same for both AO-SSB and OD-SSB for the same SSB index
Proposal 6: For Case #2, a time offset parameter for indicating an offset between AO-SSB and OD-SSB bursts is not supported  
Proposal 7: Support explicit indication of deactivation for OD-SSB via MAC-CE for all supported scenarios (i.e. Scenarios #2, #2A and #3B)
Proposal 8: Deactivation of OD-SSB when receiving SCell deactivation (Option 4) or expiry of SCell deactivation timer (Option 4A) are not supported 
Proposal 9: An additional timer for implicitly determining the value of N for the number of OD-SSB bursts is not introduced  
Appendix: Agreements on OD-SSB SCell operation
RAN1#120bis Agreements

RAN1#120 Agreements

RAN1#119 Agreements

RAN1#118bis Agreements

RAN1#118 Agreements

RAN1#117 Agreements
RAN1#116bis Agreements

RAN1#116 Agreements

3GPP TSG-RAN WG1 Meeting #121	Tdoc R1-2504015 
St Julien’s, Malta, May 19th – May 23rd, 2025

Agenda Item:	9.5.1
Source:	Ericsson 
Title:	On-demand SSB SCell operation
Document for:	Discussion

1	

Conclusion
In the previous sections we made the following observations: 
Observation 1	If a single value of number of OD-SSB bursts is configured per OD-SSB configuration, the maximum number N2 of values of number of OD-SSB bursts is equal to the maximum number M of OD-SSB configurations.
Observation 2	The functionality of Option 4 can be realized by Option 1 if a MAC CE that deactivates the OD-SSB can also deactivate the SCell.
Observation 3	The functionality of Option 4A can be realized by Option 2 if the on-demand-SSB transmission is restarted when the SCell deactivation timer is restarted.

Based on the discussion in the previous sections we propose the following:
Proposal 1	Up to M OD-SSB configurations can be configured per SCell, wherein each OD-SSB configuration includes a single value (if configured) of OD-SSB periodicity (i.e., od-ssb-periodicity), OD-SSB positions in burst (i.e., od-ssb-PositionsInBurst), and number of OD-SSB burst (i.e., od-ssb-nrofBurst), and other parameters.
Proposal 2	Support up to 8 OD-SSB configurations per SCell.
Proposal 3	Support restarting or prolonging an OD-SSB transmission at the same time as the SCell deactivation timer is restarted.
Proposal 4	Support MAC CE deactivation also for OD-SSB transmission configured with a value of number of OD-SSB bursts.
Proposal 5	Default OD-SSB periodicity (if not configured) is 20 ms.
Proposal 6	OD-SSB positions in burst can be the same or a subset of AO-SSB positions in burst both for the case of same center frequency and different center frequencies.
Proposal 7	If OD-SSB positions in burst is a subset of AO-SSB positions in burst, NW can associate a CSI report only with OD-SSB by configuring in the CSI report only the SSB indices that are in the OD-SSB burst.

3GPP TSG RAN WG1 #121		R1-2504030
St Julian’s, Malta, May 19th – 23th, 2025

Agenda Item:	9.5.1
Source:	Google
Title:	On-demand SSB for SCell
Document for:	Discussion/Decision

Conclusion
In this contribution, we provided discussion on on-demand SSB for SCell. Based on the discussion, the following proposals are provided.
Proposal 1: Support the MAC-CE for OD-SSB activation to indicate value of the action delay T for the alignment of the updated configuration for the OD-SSB for multiple UEs.
Proposal 2: For non-UE dedicated signals, the rate matching pattern should be based on both always-on SSB and OD-SSB.
Proposal 3: For UE-dedicated signals, the rate matching pattern should be based on always-on SSB only
Proposal 4: For CSI report configuration with OD-SSB only, UE reports the SSBRI based on the activated OD-SSB only.
Proposal 5: For CSI report configuration with OD-SSB only, when all the OD-SSBs are deactivated, UE assumes the CSI report configuration is deactivated.
Proposal 6: Support an LTM CSI report configuration can be associated with
Both AO-SSB and OD-SSB
OD-SSB only

3GPP TSG RAN WG1 #121			R1-2504037
St Julian’s, Malta, May 19th – 23th, 2025

Agenda item:	9.5.1
Source:	KT Corp.
Title:	Discussion on on-demand SSB SCell operation
Document for:	Discussion and decision


1. 

Conclusion
We give our proposals in this contribution as follows:

Proposal 1: Remove the bracket of the previous agreement, i.e., for a cell supporting on-demand SSB SCell operation, for configuring the number N of on-demand SSB bursts to be transmitted after on-demand SSB is indicated (i.e., od-ssb-nrofBurst),if od-ssb-nrofBurst for an on-demand SSB is configured, the on-demand SSB is deactivated based on the configured value for od-ssb-nrofBurst or via MAC CE.

Proposal 2: Support DCI based signalling to indicate on-demand SSB transmission on the cell with group-common DCI.

Proposal 3: Proposal #7-2 in [2] is supported, i.e., It is up to gNB implementation for the followings:
Whether half frame index is the same or different for AO-SSB and OD-SSB for the case when the center frequency locations of AO-SSB and OD-SSB are same
Whether PBCH payload for the same SSB index (other than SFN index, half frame index) is same or different for AO-SSB and OD-SSB for the case when the center frequency locations of AO-SSB and OD-SSB are different

Proposal 4: Regarding the spatial relation between the always-on SSB and on-demand SSB, Alt 1 is supported, i.e., it is supported that SSB indices within on-demand SSB burst can be subset of SSB indices within always-on SSB burst.

Proposal 5: Proposal #9-1 in [2] is supported, i.e., for a cell supporting on-demand SSB SCell operation, support the following rate-matching behavior.
Rate-matching for PDSCH around on-demand SSB is applied from time instance A when UE receives on-demand SSB activation signaling.
Rate-matching for PDSCH around on-demand SSB is not applied from time instance B when UE receives on-demand SSB deactivation signaling, or not applied after N on-demand SSB burst transmissions if configured/indicated.

Proposal 6: OD-SSB has less priority of transmission than the previously configured periodic signals, like RACH and CSI-RS.

Proposal 7: An on-demand SSB transmission indication for an SCell (e.g., (de)activation or parameter change) overrides a potentially ongoing on-demand SSB transmission for that SCell.

Proposal 8: Using on-demand SSB as a PL-RS/QCL RS and associated with a TCI state is not supported in Rel. 19 NES.

Proposal 9: Consider the inter-operatable RRC configuration for the periodicity and positions in burst for on-demand-SSB with always-on-SSB.

Proposal 10: Adaptation of period is supported for on-demand SSB.


5. 

3GPP TSG RAN WG1 #121			R1-2504050
St Julian’s, Malta, May 19th – 23th, 2025
Agenda Item:	9.5.1
Source:	China Telecom
Title:	Discussion on on-demand SSB operation for SCell 
Document for:	Discussion and discussion

Conclusion
In this paper, we discuss on-demand SSB operation and have the following observations and proposals.
Observation 1: There is no benefit to support DCI based initial indication for on-demand compared with RRC/MAC CE based signalling for scenario #2 and #2A.
Observation 2: OD-SSB and always-on SSB transmitted close to each other in time domain should also be avoided to save energy. 

Proposal 1: Support DCI based signalling for on-demand SSB indication for scenario #3B.  
Proposal 2: There should be no on-demand SSB and always-on SSB transmitted within a specific time period so that the largest NES gain can be acquired. 
The AO-SSB should be terminated to transmit when such situation happens.
Proposal 3: The value range of od-ssb-nrofBusrt N2 should be 2/4.
Proposal 4: On-demand SSB should be supported to be deactivated via MAC CE if od-ssb-nrofBurst of an on-demand SSB is configured. 
Proposal 5: For the deactivation of on-demand SSB, Option 1, i.e., Explicit indication of deactivation for on-demand SSB via MAC-CE, can be applied to all the scenarios. 
Proposal 6: For the deactivation of on-demand SSB, Option 4 and 4A, i.e., the deactivation of SCell, can be sued as the deactivation signal in addition to Option 2. 
Proposal 7: For the deactivation of on-demand SSB, there is no need to further support to indicate value of N can be implicitly using a timer for Option 2. 
Proposal 8: If a CSI report configuration is associated with both of AO-SSB and OD-SSB, the AO-SSB and OD-SSB can have same/different center frequency, and it is up to UE to measure both SSBs or only OD-SSB.
Proposal 9: The case that CSI report configuration is only associated with OD-SSB can only applied for the case where AO-SSB and OD-SSB can have different center frequency.

3GPP TSG RAN WG1 #121                              	R1-2504075
St Julian’s, Malta, May 19th – 23th, 2025	
	
Agenda item:	9.5.1
Source: 	Sharp
Title: 	Discussion on remaining details of on-demand SSB operation on SCell
Document for:	Discussion

Conclusions
Based on the discussion, we have the following observation and proposals:
If a PDCCH candidate and a transmitted OD-SSB are overlapped in at least one RE, the UE is not required to monitor the PDCCH candidate.
If a PDSCH resource allocation overlaps with PRBs containing OD-SSB transmission resources, the UE shall assume that the PRBs containing the OD-SSB are not available for the PDSCH reception.
Support that OD-SSB can be used as a QCL source of a TCI state at least for Case #1.

3GPP TSG RAN WG1 #121	R1- 2504092
St. Julians, Malta, May 19th – 23rd, 2025
Agenda Item:	9.5.1
Source: 	Fujitsu
Title:	Discussion on on-demand SSB SCell operation
Document for:	Discussion/Decision

Conclusions
In this contribution, we discussed on-demand SSB for SCell. The following observations and proposals are provided.
Proposal 1: For the case where the center frequency locations of AO-SSB and OD-SSB are same, half frame index can be the same or different for AO-SSB and OD-SSB.
Proposal 2: When the center frequency locations of AO-SSB and OD-SSB are different, the PBCH payload for the same SSB index may be different for AO-SSB and OD-SSB.
Proposal 3: If od-ssb-nrofBurst for an on-demand SSB is configured, the on-demand SSB can be deactivated via MAC CE.
Observation 1: Option 3 (simultaneous CD-SSB and NCD-SSB configuration as shown in Figure 3) requires BWP-specific on-demand SSB configuration to enable on-demand SSB operation for Redcap UEs. However, whether to support this option requires further discussion.
Proposal 4: RAN1 to clarify whether to support Option 3 (simultaneous CD-SSB and NCD-SSB transmission as shown in Figure 3) to enable on-demand SSB SCell operation for both non-RedCap UEs and RedCap UEs. 
Proposal 5:  For a CSI report configuration associated with both AO-SSB and OD-SSB, if the higher layer timeRestrictionForChannelMeasurements in CSI-ReportConfig is set to “Configured”, the UE shall measure the most recent SSB between OD-SSB and AO-SSB.  
Proposal 6: Support that a CSI report configuration associated with only OD-SSB is applied at least for the case where AO-SSB and OD-SSB have different center frequency location.
Proposal 7: Support a CSI report configuration associated with only AO-SSB, particularly when AO-SSB and OD-SSB have different center frequency locations (i.e., AO-SSB is CD-SSB while OD-SSB is NCD-SSB). 
A CSI report configuration associated with OD-SSB for a short time to enable fast SCell activation, and another CSI report configuration associated with AO-SSB for long-term beam management and measurement.
Observation 2: In the scenario where AO-SSB and OD-SSB have different center frequency locations (i.e., AO-SSB is CD-SSB while OD-SSB is NCD-SSB), if a CSI report configuration associated with only AO-SSB is supported, it is essential for a UE to determine whether a configured CSI report configuration is associated with AO-SSB or OD-SSB. 
Proposal 8: In the scenario where AO-SSB and OD-SSB have different center frequency locations (i.e., AO-SSB is CD-SSB while OD-SSB is NCD-SSB), if a CSI report configuration associated with only AO-SSB is supported: 
The CSI resource configuration enhancement can be introduced to differentiate on-demand SSB and always-on SSB.
Proposal 9: For CSI resource configuration enhancement for on-demand SSB associated with CSI report configuration, the following two options can be considered. 
Option A: CSI resource enhancement at the level of the resource set list
 To specify a dedicated resource set list for on-demand SSB.
Option B: CSI resource enhancement at the level of CSI-SSB resource set
To introduce an on-demand SSB indicator within the CSI-SSB-ResoureSet.
Proposal 10: If a newly defined resource set parameter, e.g., CSI-OD-SSB-ResourceSet, is supported, the corresponding enhancement in the aperiodic trigger state list should be considered as well.
E.g., CSI-OD-SSB-ResourceSet should be included in CSI-AperiodicTriggerStateList.
Proposal 11: For a CSI report configuration configured with reportConfigType set to periodic, support Alt 1 which aligns with the legacy CSI configuration mechanism.
The CSI report configuration can be associated with on-demand SSB indicated by RRC and cannot be associated with on-demand SSB indicated by MAC CE.
Proposal 12: None of the following configurations are considered as on-demand SSB indicated by RRC:
Option 1: an on-demand SSB configuration comprising od-ssb-nrofBurst.
Option 2: an on-demand SSB configuration activated by RRC (via an ‘active’ state) while deactivated by MAC CE.
Option 3: an on-demand SSB configuration activated by MAC CE while deactivated by RRC.
Observation 3: In the existing spec on SCell, only periodic CSI-RS can be configured for beam failure detection purposes, while either SSB or periodic CSI-RS can be configured for beam failure recovery.
Proposal 13: Support candidate beam selection based on on-demand SSB in Case#1.
Proposal 14: In case#1, when on-demand SSB is activated,
The downlink SS/PBCH SSS EPRE can be derived from the on-demand SSB downlink transmit power given by the parameter od-ss-PBCH-BlockPower.
The downlink CSI-RS EPRE can be derived from the on-demand SSB downlink transmit power given by the parameter od-ss-PBCH-BlockPower and CSI-RS power offset given by the parameter powerControlOffsetSS.

3GPP TSG RAN WG1 #121	R1-2504107
St Julian’s, Malta, May 19th – 23rd, 2025
Agenda item:	9.5.1
Source: 	Lenovo
Title: 	On-demand SSB SCell operation
Document for:	Discussion and Decision

Conclusion
In summary, we have following proposals for on-demand SSB for SCell:
Proposal 1: Adopt the following TP for TS38.213.
Proposal 2: If od-ssb-nrofBurst for an on-demand SSB is configured, the on-demand SSB is deactivated only based on the configured value for od-ssb-nrofBurst. 
Proposal 3: Do not support Option 4 and Option 4a on top of Option 2 for deactivation of OD-SSB. 

3GPP TSG RAN WG1 Meeting #121			    			             R1-2504141
St Julian’s, Malta, May 19th – 23th, 2025

Source:	ETRI
Title:		Discussion on On-demand SSB SCell operation
Agenda item:	9.5.1
Document for:	Discussion/Decision

Summary
In this contribution, we made the following proposals on on-demand SSB SCell operation.

General aspects
Proposal 1: Regarding whether on-demand SSB is cell-defining or not, additional support for configuring the on-demand SSB as a CD-SSB located on the synchronization raster is not necessary.

Signaling methods for on-demand SSB TX indication
Proposal 2: It is proposed not to support DCI-based indication for indicating on-demand SSB transmission.

Contents of on-demand SSB configuration/indication
Proposal 3: It is proposed to specify that on-demand SSB configuration is cell-specific, rather than BWP-specific.

TX behavior of on-demand SSB burst
Proposal 4: It is proposed to discuss whether the UE is required to support BWP switching on the SCell with on-demand SSB for Case #1.
If BWP switching is supported, the switched BWP shall include on-demand SSB.
Alternatively, BWP switching is not supported with on-demand SSB operation.

Time/Frequency/Spatial relation between always-on SSB and on-demand SSB
Proposal 5: For the case when the center frequency locations of always-on SSB and on-demand SSB are same,
It is up to gNB implementation whether half frame index is the same or different for always-on SSB and on-demand SSB
Proposal 6: For the case where the center frequency locations of the always-on SSB and the on-demand SSB are different:
It is up to gNB implementation whether on-demand SSB is configured as a CD-SSB.
It is up to gNB implementation whether PBCH payload for the same SSB index (excluding SFN index and half frame index) is the same or different between always-on SSB and on-demand SSB.
Proposal 7: It is proposed that when a conflict occurs due to overlapping of always-on SSB and on-demand SSB in both time and frequency domains, the network should prioritize the transmission of the always-on SSB and drop the on-demand SSB.
Proposal 8: It is proposed to specify a configuration limitation that the periodicity of on-demand SSB shall be equal to or smaller than that of always-on SSB.
Proposal 9: It is proposed not to support the case where the SSB indices within on-demand SSB burst are a subset of those within always-on SSB burst.
Proposal 10: It is proposed not to support the case where the SSB indices within on-demand SSB burst can be separately configured from SSB indices within always-on SSB burst.

Issue on Draft CR for TS 38.213
Proposal 11: It is proposed to reflect the configuration limitation (i.e., whether on-demand SSB can be configured on the same frequency location as always-on SSB depending on CD-SSB status) in TS 38.331 rather than TS 38.213.

3GPP TSG RAN WG1 #121		                        R1-2504176
St Julian’s, Malta, May 19th-23th, 2025
Source: 	Transsion Holdings
Title:	Discussion on on-demand SSB SCell operation
Agenda item:	9.5.1
Document for:	Discussion & Decision

Conclusions
In this contribution,some views about on-demand SSB SCell operation are discussed, and the following proposals are made.
Proposal 1  On-demand SSB for CD-SSB located on synchronization raster cannot be supported.
Proposal 2  It is recommended to support Alt C: Do not support the case where always-on SSB is CD-SSB and not on a synchronization raster.
Proposal 3  DCI based signaling to indicate on-demand SSB transmission can be supported.
Proposal 4  If DCI based signaling support on-demand SSB transmission, DCI is UE-specific.
Proposal 5  Option 4, 4A can be used to deactivate on-demand SSB transmission.
Proposal 6  For case #2, using time offset between always-on SSB and on-demand SSB to define time domain location of on-demand SSB should be supported.

3GPP TSG RAN WG1 #121		R1-2504192
St Julian’s, Malta, May 19th - 23th, 2025 

Source:	OPPO
Title:	Discussion on the enhancement to support on demand SSB SCell operation
Agenda Item:	9.5.1
Document for:	Discussion and Decision

Conclusion
In this contribution, we provide our views on OD-SSB SCell operation for Rel-19 NES. The following proposals are listed.
Proposal 1: If no AO-SSB on the cell, the SSB indexes for RO mapping should be the union of all the configured candidate SSB indexes for OD-SSB bursts.
Proposal 2: If AO-SSB is periodically transmitted on the cell, OD-SSB indexes should be same or a subset of AO-SSB indexes, and the legacy SSB-RO mapping relationship is reused.
Proposal 3: Support the same half frame index for AO-SSB and OD-SSB for the case when the center frequency locations of AO-SSB and OD-SSB are same.
Proposal 4: PBCH payload for the same SSB index (other than SFN index, half frame index) can be different for AO-SSB and OD-SSB for the case when the center frequency locations of AO-SSB and OD-SSB are different. 
Proposal 5: Send an LS to RAN2 to request it to capture the following restrictions in TS 38.331, and remove the following draft CR from TS 28.213. 

3GPP TSG RAN WG1 #121			R1-2504235
St Julian’s, Malta, May 19th – 23th, 2025

Agenda Item:	9.5.1
Source:	Panasonic
Title:	Discussion on on-demand SSB SCell operation
Document for:	Discussion/Decision

Conclusion
Based on the discussion, the following proposals are highlighted: 
Proposal 1: L3 measurement based on on-demand SSB should be supported in general for all Scenarios.  
Proposal 2: L1 measurement when on-demand SSB is ON should be supported at least for Scenario 2A, 3A and 3B i.e., after the SCell activation command is received. On Scenario 2, on-demand SSB based L1 measurement for LTM is not supported.
Proposal 3: For RRC triggered/indicated on-demand SSB, the periodic, semi-persistent and aperiodic CSI report should be supported with current CSI mechanism.
Proposal 4: For MAC CE triggered/indicated on-demand SSB, semi-persistent and aperiodic CSI report should be supported with enhancement that on-demand SSB is expected to be available when CSI report is active. On periodic CSI report, although our first preference is not to support, we can be flexible if the specification impact can be minimized. 
Proposal 5: For group common DCI triggered/indicated on-demand SSB, if supported, only semi-persistent and aperiodic CSI report should be supported.
Proposal 6: On-demand SSB for time/frequency synchronization and TCI state reference resource should be supported in Scenario #3B and Case#1.
Proposal 7: For a cell supporting on-demand SSB SCell operation, for configuring the number N of on-demand SSB bursts to be transmitted after on-demand SSB is indicated (i.e., od-ssb-nrofBurst), if od-ssb-nrofBurst for an on-demand SSB is configured, the on-demand SSB is deactivated based on the configured value for od-ssb-nrofBurst or via MAC CE.
Proposal 8: In addition to RRC and MAC CE based SSB trigging, DCI-based on-demand SSB triggering and deactivation indication is supported by the DCI format 2_9 framework defined in 9.5.3.
Proposal 9: On whether/how to indicate time offset between always-on SSB and on-demand SSB, we can see the on-demand SSB feature can work without supporting new pattern for sake of progress. If a new pattern is to be supported, the specification efforts and impact need to be minimized.
Proposal 10: O_cpu for L1-RSRP measurement should be counted as 1, despite whether both or one of AO-SSB and OD-SSB are/is measured.
Proposal 11: When a CSI report is associated with both AO-SSB and OD-SSB, the CPU occupied OFDM symbols should be from the first symbol of either AO-SSB or OD-SSB resource, respective latest SSB occasion no later than the corresponding CSI reference resource, despite whether both or one of AO-SSB and OD-SSB are/is measured.
Proposal 12: When both AO-SSB and OD-SSB are configured and associated with a CSI report, and if the SSB beams in a burst are different, and if the higher layer timeRestrictionForChannelMeasurements in CSI-ReportConfig is set to “Configured”, legacy UE behaviour is reused to determine which set of SSB to measure and select the reported SSBRI for the best beam.
Proposal 13: When both AO-SSB and OD-SSB are configured and associated with a CSI report, and if the SSB beams in a burst are different, to consider below two alternatives:
Alt 1 (preferable): Both sets of SSBs are measured. The best beam SSBRI is selected from the beams of the union of AO-SSB and OD-SSB. For the measurement of the beams with the same SSB indices (i.e., QCLed) between two sets of SSB, it is allowed and up to UE implementation to measure one of or both QCLed SSB beams.
Alt 2: Only OD-SSB is measured. The best beam SSBRI is selected from the beams of OD-SSB.

3GPP TSG RAN WG1 #121     		                 R1-2504247
St Julian’s, Malta, May 19th – 23rd, 2025

Agenda Item:	9.5.1
Source: 	LG Electronics
Title: 	On-demand SSB SCell operation
Document for:	Discussion and decision

Conclusions

In this contribution, on-demand SSB SCell operation for NES was discussed, and the followings were proposed.

Proposal #1: For a cell supporting on-demand SSB SCell operation and for Case #2 (i.e., Always-on SSB is periodically transmitted on the cell), if AO-SSB and OD-SSB have the different center frequencies,
A CSI report configuration can be associated with OD-SSB only,
In addition, considering the case where OD-SSB is deactivated during Scenario #3B,
Alt 1: A CSI report configuration can be associated with both of AO-SSB and OD-SSB.
Alt 2: A CSI report configuration can be associated with AO-SSB only.

Proposal #2: Introduce new higher layer parameters ‘od-ssb-Index-RSRP’, ‘od-ssb-Index-SINR’, ‘od-ssb-Index-RSRP-Index’ and ‘od-ssb-Index-SINR-Index’ as components of reportQuantity-r19 for a CSI report configuration.
If reportQuantity for a CSI report configuration is set to ‘od-ssb-Index-RSRP’, ‘od-ssb-Index-SINR’, ‘od-ssb-Index-RSRP-Index’ or ‘od-ssb-Index-SINR-Index’, the CSI report configuration is associated with OD-SSB only.
Otherwise, if reportQuantity for a CSI report configuration is set to ‘ssb-Index-RSRP’, ‘ssb-Index-SINR’, ‘ssb-Index-RSRP-Index’ or ‘ssb-Index-SINR-Index’, the CSI report configuration is associated with both of AO-SSB and OD-SSB.

Proposal #3: For a cell supporting on-demand SSB SCell operation and for Case #2 (i.e., Always-on SSB is periodically transmitted on the cell), if the higher layer parameter timeRestrictionForChannelMeasurements in CSI-ReportConfig is set to "Configured",
If OD-SSB is activated for the SCell,
The UE shall derive the channel measurements for computing L1-RSRP or L1 SINR reported in uplink slot n based on only the most recent, no later than the CSI reference resource, occasion of “OD-SSB” associated with the CSI resource setting.
Otherwise, if OD-SSB is deactivated for the SCell,
The UE shall derive the channel measurements for computing L1-RSRP or L1 SINR reported in uplink slot n based on only the most recent, no later than the CSI reference resource, occasion of “AO-SSB” associated with the CSI resource setting.

Proposal #4: For a CSI report configuration configured with reportConfigType set to periodic, support Alt 2 (i.e., The CSI report configuration can be associated with OD-SSB regardless of signaling mechanism for indicating OD-SSB transmission).

Proposal #5: Before OD-SSB is indicated to be transmitted or after on-demand SSB transmission is deactivated, the UE is not required to perform L1 measurement or CSI reporting even though it has received the CSI report configuration for L1 measurement and reporting based on OD-SSB.

Proposal #6: For Case #1, following is supported for QCL between the first OD-SSB and the second OD-SSB.
SS/PBCH blocks with the same SSB indexes for the first OD-SSB and the second OD-SSB are quasi co-located with respect to Doppler spread, Doppler shift, average gain, average delay, delay spread, and when applicable, spatial RX parameters. 

Proposal #7: When on-demand SSB transmission is indicated by a RRC, UE expects that the value of N is NOT provided by the RRC.  
The on-demand SSB activated by RRC signaling can be deactivated by applying Option 1 (Explicit indication of deactivation for on-demand SSB via MAC-CE for on-demand SSB transmission indication) and cannot be deactivated by applying Option 2 (Configuration/indication of the number N of on-demand SSB bursts to be transmitted after on-demand SSB is indicated). 

Proposal #8: RAN1 to discuss the following values for od-ssb-nrofBurst as the starting point and send an LS to RAN4 to confirm whether those values are feasible or not.
For FR1, the value range of od-ssb-nrofBurst is {5, 10, 15, 20, 25, 30, 40, 50}.
For FR2, the value range of od-ssb-nrofBurst is {25, 30, 40, 50, 75, 100, 150, 200}.

Proposal #9: For two options to deactivate on-demand SSB transmission from a UE perspective, Option 1 (Explicit indication of deactivation for on-demand SSB via MAC-CE for on-demand SSB transmission indication) and Option 2 (Configuration/indication of the number N of on-demand SSB bursts to be transmitted after on-demand SSB is indicated) should be used/adopted exclusively. Update the previous agreement as follows.

Proposal #10: Support on-demand SSB configuration per BWP similar to NCD-SSB configured with the higher layer parameter nonCellDefiningSSB. 

Proposal #11: Adopt Alt A.
Alt A: If always-on SSB is CD-SSB and not on a synchronization raster, the frequency location of on-demand SSB can be same or different from the frequency location of always-on SSB, subject to its configuration.

Proposal #12: For the following parameter, multiple candidate values can be configured (including the case where no candidate values are configured) by RRC and the applicable value can be indicated by MAC CE for on-demand SSB transmission indication for the cell. 
Frequency of the on-demand SSB (i.e., od-ssb-absoluteFrequency)

Proposal #13: For Case #2, the periodicity of OD-SSB (i.e., od-ssb-Periodicity) can be absent within od-ssb-config.
If absent, the periodicity of OD-SSB is the same as that of AO-SSB (i.e., ssb-Periodicity).

Proposal #14: Adopt the following TP in TS 38.213 Section 4.4.

Proposal #15: For Case #1, and for Case #2 where AO-SSB and OD-SSB have the same center frequency, OD-SSB can be used for the following purposes.
Beam failure recovery
Path-loss estimation reference signal
QCL reference signal

Proposal #16: For Case #1, RO validation before SSB-to-RO mapping is performed by assuming that no OD-SSB is activated.

Proposal #17: For Case #2, RO validation before SSB-to-RO mapping is performed based on only AO-SSB, as in legacy.

Proposal #18: For Case #1, SSB-to-RO mapping is performed based on the union of od-ssb-PositionsInBurst parameters configured by od-ssb-config.

Proposal #19: For Case #2, SSB-to-RO mapping is performed based on only AO-SSB, as in legacy.

Proposal #20: After SSB-to-RO mapping, if an RO is collided with activated OD-SSB or located within  symbols after a last symbol of activated OD-SSB, UE does not transmit PRACH within the RO.

Proposal #21: If at least one RE for a PDCCH candidate overlaps with at least one RE of a candidate activated OD-SSB corresponding to parameters indicated in od-ssb-config, the UE is not required to monitor the PDCCH candidate.

Proposal #22: The UE shall assume that the PRBs containing activated OD-SSB transmission resources are not available for PDSCH in the OFDM symbols where activated OD-SSB is transmitted.

3GPP TSG RAN WG1 #121           	                                  R1-2504262
St Julian’s, Malta, May 19th – 23th, 2025
Agenda Item: 9.5.1
Source: MediaTek Inc.
Title: On-demand SSB SCell operation
Document for: Discussion and decision

Conclusion
In this contribution, we focus on the discussions of on-demand SSB SCell operation and have the following proposals: 

Proposal 1: When there is always-on SSB transmitted in the cell, use "SFN offset" and "half frame index" to indicate the time domain position of on-demand SSB. No need to indicate time offset between always-on SSB and on-demand SSB.

Proposal 2: At least ssb-SubcarrierOffset (k_ssb, see Fig. 1) inside MIB would be different for AO-SSB and OD-SSB when center frequency locations of always-on SSB and on-demand SSB are different.

3GPP TSG RAN WG1 #121		R1-2504325
St Julian’s, Malta, May 19th – 23th, 2025

Agenda Item:	9.5.1
Source:	Apple
Title:	On-demand SSB SCell Operation
Document for:	Discussion/Decision
 

ConclusionAgreement
The following combination of scenarios and cases for indicating OD-SSB are not supported in Rel-19
Scenario #3A and Case #1
Scenario #3A and Case #2
Proposed wording: UE shall not assume OD-SSB indication is received after receiving SCell activation command and before SCell activation is completed.
Above does not impact discussion on SSB periodicity adaptation in time domain

 

3GPP TSG RAN WG1 #121			            R1-2504398
St Julian’s, Malta, May 19th – 23rd, 2025
Agenda item:	9.5.1
Source: 	Qualcomm Incorporated
Title: 	On-demand SSB operation for Scell
Document for:	Discussion/Decision

Conclusion
The contribution has discussed our views on remaining aspects to support on-demand SSB operation for Scell. In particular, we make the following observations and proposals:
Observation 1: Having on-demand SSB configured as cell-defining SSB has negative impact to both legacy idle/inactive UEs and R19 idle/inactive UEs.
Observation 2: At least for Case #2, the adaptation of SSB burst periodicity via DCI 2_9 in AI 9.5.3 can already achieve the same purpose of DCI based signaling to indicate on-demand SSB transmission.

Proposal 1: On-demand SSB for cell defining SSB located on synchronization raster is not supported
Proposal 2: DCI based signaling to indicate on-demand SSB transmission on the cell is not supported.
Proposal 3: For the case when the center frequency locations of always-on SSB and on-demand SSB are same,
For Alt Time C-1, the half-frame index is different for AO-SSB and OD-SSB if the union of AO-SSB transmission and OD-SSB transmission has a periodic time domain pattern of 5ms periodicity. Otherwise, the half-frame index is identical for AO-SSB and OD-SSB.
For Alt Time C-2, the half-frame index may be different for AO-SSB and OD-SSB.
Proposal 4: For the case when the center frequency locations of always-on SSB and on-demand SSB are different, PBCH payload (other than SFN index, half frame index) is the same for AO-SSB and OD-SSB for the same SSB index.
Proposal 5: The case where always-on SSB is CD-SSB that is not on sync raster (Alt. C) is not supported.
Proposal 6: When a CSI report configuration is associated with both AO-SSB and OD-SSB, it is up to UE to measure both SSBs or one of them if the higher layer timeRestrictionForChannelMeasurements in CSI-ReportConfig is set to “Configured”.
Proposal 7: For OD-SSB Case #1, the following is considered for PRACH occasion validation rules and SSB-RO mapping rules:
For RRC based indication of OD-SSB transmission, the PRACH occasion validation rules and SSB-RO mapping rules are determined based on OD-SSB configuration in the RRC.
For MAC-CE based indication of OD-SSB transmission, the PRACH occasion validation rules and SSB-RO mapping rules are determined based on OD-SSB configuration in RRC and the latest MAC-CE indicating OD-SSB transmission at or before the time UE receives Scell activation command.
Proposal 8: For OD-SSB Case #2, PRACH occasion validation rules and SSB-RO mapping rules are not impacted by OD-SSB transmission.
Proposal 9: For OD-SSB Scell operation, the UE is not expected to transmit PRACH in a valid PRACH occasion if the occasion precedes a SS/PBCH block in the PRACH slot and does not start at least  symbols after a last SS/PBCH block reception symbol where 
 is provided in Table 8.1-2 of TS 38.213, and 
SS/PBCH block is the SS/PBCH block that is transmitted in response to RRC/MAC-CE based indication of OD-SSB transmission.
Proposal 10: Adopt the following update to Clause 10 of TS 38.213 for PDCCH monitoring.


Proposal 11: Adopt the following update to Clause 5.1.4 of TS 38.214 for PDSCH resource mapping.


Proposal 12: The maximum number of SSB burst periodicities to be configured as part of OD-SSB configuration is 2.

Proposal 13: The reference for determining the MAC-CE based indication/deactivation timeline of OD-SSB transmission is slots for the PUCCH transmission (similar to legacy Scell activation/deactivation timeline). In particular, adopt the following update to TS 38.213.

3GPP TSG RAN WG1 #121			R1-2504505
St Julian’s, Malta, May 19th – 23rd, 2025

Source:	NTT DOCOMO, INC.
Title:	Discussion on on-demand SSB SCell operation
Agenda Item:	9.5.1
Document for:  Discussion and Decision

Conclusions
In this contribution, we provided the following observations and proposals of on-demand SSB SCell operation for network energy saving.
Proposal 1:
Support OD-SSB for CD-SSB located on sync-raster. 
Proposal 2:
Support, half frame index can be the same or different for AO-SSB and OD-SSB. It is up to NW implementation.
Proposal 3:
In terms of the content of PBCH payload for both OD-SSB and AO-SSB with same or different center frequency,
We do not support the restriction that the PBCH payload for the same SSB index (other than SFN index, half frame index) should be the same for AO-SSB and OD-SSB
E.g., the value of PDCCH-ConfigSIB1, k_ssb and cell barring information can be different. 
Proposal 4:
When AO-SSB is CD-SSB, 
No additional condition should be added to the Alt. 1
We support Alt. A for the case when
OD-SSB and AO-SSB are located on the same frequency.
OD-SSB and AO-SSB are not located on the same frequency with the restriction that UE does not require to do RF tuning.
Observation 1: 
It seems unclear which combinations b/w AO and OD-SSB are supported when AO-SSB is NCD-SSB in case #2.
Proposal 5:
Support the following combinations when AO-SSB is NCD-SSB in case #2.
Table. 1 combination for the case when AO-SSB is NCD-SSB
Same restriction that was already agreed for the case of Alt. 1 should be applied to the supported combinations.
Proposal 6:
For the applicable SSB-index arrangements for OD-SSB in case #2, we support at least following options.
Option 1: The set of SSB indices of AO-SSB and those of OD-SSB are identical. 
Option 2: The set of SSB indices of OD-SSB becomes a subset of the set of SSB indices of AO-SSB. 
Proposal 7:
For the spatial relationship between AO-SSB and OD-SSB,
When AO-SSB and OD-SSB have the same center frequency, support the QCL assumption for the same SSB-index regardless of whether the SSB indices within OD-SSB burst are identical to those within AO-SSB or not.
When AO-SSB and OD-SSB do not have the same center frequency, QCL assumption should not always be assumed.
Study whether/how to use OD-SSB as QCL source RS on behalf of/in addition to AO-SSB in case #1 and case #2.
Proposal 8:
For the value range of od-ssb-nrofBurst, 
The minimum value can be considered based on the current RRM requirement on L3 measurement for unknown cell, or it is up to RAN4.
Observation 2:
When NW provides a finite number of N transmission, it is likely that large N can be configured and transmitted, resulting in an exceeding the number of OD-SSB transmissions even after the intended operation using OD-SSB is completed.
Proposal 9:
For deactivation mechanism, we support either one from following directions.
1. if od-ssb-nrofBurst for an OD-SSB is configured, the OD-SSB can be deactivated via MAC CE
2. deactivation mechanism of option 4/4a should be supported.
Observation 3:
It is important for NW to know which RS to be used for the measurement when the timeRestrictionForChannelMeasurement is set to “configured”. 
Proposal 10:
For a CSI report configuration that can be associated with both AO-SSB and OD-SSB, 
We support not to let UE implementation for which SSBs to be used when timeRestrictionForChannelMeasurement is set to “configured”.
Proposal 11:
For a CSI report configuration that can be associated with OD-SSB only,
Support this regardless of the frequency location between AO-SSB and OD-SSB are the same or different.
Observation 4:
In order for NW to know which configured SCell and beam is best to be activated with minimizing NW TX, L1 measurement based on OD-SSB is beneficial.

Proposal 12:
Support L1 measurement based on OD-SSB in scenario #2/case #1 by reusing the existing LTM mechanism.

TDoc file reading error

3GPP TSG RAN WG1 #121	R1-2504554
St Julian’s, Malta, May 19th – 23rd, 2025

Agenda Item:	9.5.1
Source:	KDDI
Title:	Discussion on on-demand SSB SCell operation
Document for:	Discussion and decision

Conclusion
In this contribution, we discussed remaining issues that should be considered in this work item regarding on-demand SSB SCell operation. Based on the discussion above, we made the following proposals.
Proposal 1: If the higher layer parameter timeRestrictionForChannelMeasurements in CSI-ReportConfig is set to "Configured", the UE shall derive the channel measurements based on only the most recent, no later than the CSI reference resource, occasion of AO-SSB or OD-SSB.
Proposal 2: A CSI report configuration associated with OD-SSB only applies at least for the case where AO-SSB and OD-SSB have the different center frequencies.
Proposal 3: CSI report configuration configured with reportConfigType set to periodic can be associated with on-demand SSB indicated by RRC.
Proposal 4: DCI based signaling to indicate on-demand SSB transmission on the cell is not supported.
Proposal 5: A UE shall assume that the PRBs containing SS/PBCH block transmission resources are not available for PDSCH from time instance A when the UE receives on-demand SSB activation signaling until time instance B when the UE receives on-demand SSB deactivation signaling or after the number N of on-demand SSB bursts if configured/indicated.
Proposal 6: PDSCH for which rate-matching is performed by UE for on-demand SSB is the PDSCH scheduled UE-dedicatedly.
Proposal 7: Study whether UE transmits PUSCH, PUCCH or PRACH in cells other than the cell transmitting OD-SSB in the slot if the transmission would overlap with any symbol from the set of symbols corresponding to the OD-SSB in case of directional collision handling on half-duplex operation in TDD CA with same SCS.

TDoc file reading error

3GPP TSG RAN WG1 Meeting #121	                                  R1-2504602
St Julian’s, Malta, May 19th – 23th, 2025

Agenda Item:	9.5.1
Source:	CEWiT
Title:	Discussion on on-demand SSB Scell operation.
Document for:	Discussion 

Conclusion
In this contribution, we discussed the techniques required for on-demand SSB SCell operation and following proposals are made,
Observation 1: SSB indices within on-demand SSB equal to SSB indices within always-on SSB burst cause unnecessary SSB transmissions in areas with non uniform UE density.
Observation 2: If both AO-SSB and on-demand SSB are configured for L1 measurement, the UE generates a single tracking process to determine SSB locations based on legacy starting symbol indices.
Proposal 1: Support “Alt 1: It is supported that SSB indices within on-demand SSB burst can be subset of SSB indices within always-on SSB burst” for spatial relation between the always-on SSB and on-demand SSB.
Proposal 2: Support allowing the half-frame index to be either the same or different, without restriction.
Proposal 3: Support MAC CE-based deactivation as an optional enhancement on top of od-ssb-nrofBurst when configured.
Observation 4: On-demand SSB impacts the need and validity of periodic RACH occasions and their association with SSBs, requiring adjustments to ensure efficient RRC connection establishment.
Proposal 4: Support handling the impacts of on-demand SSB on RACH occasions for RRC connection establishment.
Observation 5: UE not receiving the SSB after on-demand SSB operation leads to unnecessary monitoring by the UE and negative impacts on performance.
Proposal 5: Support handling of the case where the UE cannot receive SSB after the on-demand SSB operation.

3GPP TSG RAN WG1 #121			R1- 2504744
St Julian’s, Malta, May 19th – 23rd, 2025

Agenda Item:	9.5.1
Source: 	Moderator (LG Electronics)
Title: 	Summary #1 of on-demand SSB for NES
Document for:	Discussion and decision

Conclusion
The following combination of scenarios and cases for indicating OD-SSB are not supported in Rel-19
Scenario #3A and Case #1
Scenario #3A and Case #2
Above does not impact discussion on SSB periodicity adaptation in time domain

Agreement
Regarding the relation in terms of frequency location (i.e., center frequency) between the always-on SSB and on-demand SSB,
Alt 1: If always-on SSB is CD-SSB on a synchronization raster, the frequency location of on-demand SSB is different from the frequency location of always-on SSB.
On-demand SSB is not on sync raster
AO-SSB and OD-SSB are located in the same BWP
FFS: Additional conditions
Subject to separate UE capability
Note: UE is not required to measure both AO-SSB and OD-SSB

Agreement
Regarding the relation in terms of time location between the always-on SSB and on-demand SSB,
For the case when the center frequency locations of always-on SSB and on-demand SSB are same,
Alt Time-C: RAN1 specification has no restriction with regards to overlapping
From RAN1 perspective,
Alt Time-C1: The case that, during OD-SSB transmission, the union of AO-SSB transmission and OD-SSB transmission has a periodic time domain pattern is supported (the interval between SSB bursts is even and supported in legacy specification).
Alt Time-C2: The case that, during OD-SSB transmission, the union of AO-SSB transmission and OD-SSB transmission has a non-periodic time domain pattern is supported.
It is up to RAN4 to define requirements, if any, corresponding to both or either of Alt Time-C1 or Alt Time-C2
At least the following is supported: PBCH payload for the same SSB index (other than SFN index, half frame index) is the same for AO-SSB and OD-SSB 
FFS: Whether half frame index is the same or different for AO-SSB and OD-SSB
For the case when the center frequency locations of always-on SSB and on-demand SSB are different,
Alt Time-C: RAN1 specification has no restriction with regards to overlapping
UE assumes that frequency resources of always-on SSB are not overlapped with those of on-demand SSB in frequency domain.
AO-SSB and OD-SSB are located in the same BWP
FFS: PBCH payload for the same SSB index (other than SFN index, half frame index) should be the same for AO-SSB and OD-SSB 
NOTE: AO-SSB periodicity is not adapted
Send an LS to RAN4 to inform them of the above agreement. Final LS in R1-2501633.

Agreement
For the case where SCell with on demand SSB transmission and cell with signalling transmission have different numerology, when UE determines time instance A, the SCS to determine the value of T is down selected among the following options
Option 1: the SCS of the active DL BWP where UE receives MAC CE for on-demand SSB transmission indication
Option 2: the minimum of “the SCS of the active DL BWP where UE receives MAC CE for on-demand SSB transmission indication” and “the SCS of the active DL BWP where UE receives on-demand SSB”
Option 3: the SCS of the active UL BWP where the UE transmits ACK corresponding to the MAC-CE for on-demand SSB transmission indication

RAN1#120bis

Agreement
For the case where SCell with on demand SSB transmission and cell with signalling transmission have different numerology, adopt Option 3 to determine SCS for  for determining T
Option 3: the SCS of the active UL BWP where the UE transmits ACK corresponding to the MAC-CE for on-demand SSB transmission indication

Agreement
For the case when the center frequency locations of always-on SSB and on-demand SSB are different, at least the following is supported for QCL between AO-SSB and OD-SSB
SS/PBCH blocks with the same SSB indexes for always-on SSB and on-demand SSB are quasi co-located with respect to Doppler spread, Doppler shift, average gain, average delay, delay spread, and when applicable, spatial RX parameters.
When a signal/channel is configured to be QCLed with a SSB index, the signal/channel is QCLed with the same SSB index of always-on SSB and on-demand SSB (if transmitted) with the same QCL parameters according to existing specifications

Agreement
For a cell supporting on-demand SSB SCell operation, for configuring the number N of on-demand SSB bursts to be transmitted after on-demand SSB is indicated (i.e., od-ssb-nrofBurst),
Alt 2: The value range of od-ssb-nrofBurst is {N2 integer values}
N2= [8]
If od-ssb-nrofBurst for an on-demand SSB is NOT configured, the on-demand SSB is deactivated via MAC CE. 
If od-ssb-nrofBurst for an on-demand SSB is configured, the on-demand SSB is deactivated based on the configured value for od-ssb-nrofBurst [or via MAC CE]. 

Agreement
Upon the reception of MAC CE for deactivating on-demand SSB, UE expects that on-demand SSB is NOT transmitted from time instance B.
Time instance B’ is T slots after the slot where UE receives a signalling from gNB to deactivate on-demand SSB. If time instance B’ falls within an on-demand SSB burst, time instance B is the ending of the slot containing the last actually transmitted SSB index within the on-demand SSB burst, otherwise, time instance B = time instance B’.
As agreed in previous RAN1 meeting, the SSB time domain positions of on-demand SSB burst are configured by gNB.
As agreed in previous RAN1 meeting, the location(s) (e.g., SFN offset, half frame index) in the time domain of “possible” on-demand SSB burst and SSB position within the burst should be configured by the gNB
(Working assumption) T is not less than T_min=+1 where slot n+m is a slot indicated for PUCCH transmission with HARQ-QCK information when the UE receives MAC CE signaling to deactivate on-demand SSB ending in slot n, and  is as defined in current specification.
(Working assumption) T=T_min
RAN4 to confirm the above two working assumptions
 is based on the SCS of the active UL BWP where the UE transmits ACK corresponding to the MAC-CE for on-demand SSB transmission indication

Agreement
For a cell supporting on-demand SSB SCell operation, at least for the following parameter(s) (in addition to agreed ones), multiple candidate values can be configured (includes the case where no candidate values are configured) by RRC and the applicable value can be indicated by MAC CE for on-demand SSB transmission indication for the cell.
SSB positions within an on-demand SSB burst by using signaling similar to ssb-PositionsInBurst (i.e., od-ssb-PositionsInBurst) for the following cases
The case where center frequency of AO-SSB and OD-SSB are different
Case 1
Number N of on-demand SSB bursts to be transmitted after on-demand SSB is indicated (i.e., od-ssb- nrofBurst)
FFS: Additional restrictions

Agreement
LS to RAN4 on time instance B for on-demand SSB SCell operation is agreed. Final LS in R1-2503108.

Agreement
For a cell supporting on-demand SSB SCell operation,
Frequency of the on-demand SSB (i.e., od-ssb-absoluteFrequency) can be absent for Case #2
If absent, the center frequency of on-demand SSB is the same as that of always-on SSB.
od-ssb-PositionsInBurst, if provided, has the same bitmap structure as ssb-PositionsInBurst provided in ServingCellConfigCommon, that is od-ssb-PositionsInBurst is choice of 4-bit shortBitmap, 8-bit mediumBitmap, or 64-bit longBitmap.
od-ssb-PositionsInBurst can be absent for Case #2
If absent, od-ssb-PositionsInBurst is the same as ssb-PositionsInBurst provided in ServingCellConfigCommon.

Agreement
For a cell supporting on-demand SSB SCell operation, the following combinations of scenarios and cases are supported for indicating OD-SSB using a MAC-CE.
Scenario #3B and Case #1
In the above combinations of scenarios and cases, the MAC-CE is used only for updating the transmission parameter of a transmitted OD-SSB for the cell since the OD-SSB has been transmitted according to NW indication.
Scenario #3B and Case #2
In the above combinations of scenarios and cases, the MAC-CE is used only for updating the transmission parameter of a transmitted OD-SSB for the cell since the OD-SSB has been transmitted according to NW indication.

Agreement
For a cell supporting on-demand SSB SCell operation, for Case #1 (i.e., No always-on SSB on the cell)
UE does not expect the OD-SSB transmission indicated by RRC/MAC-CE to be deactivated while the SCell is activated.

Agreement
For a cell supporting on-demand SSB SCell operation and for Case #2 (i.e., Always-on SSB is periodically transmitted on the cell),
A CSI report configuration can be associated with 
both of AO-SSB and OD-SSB 
Which SSB to measure is up to UE implementation as long as RAN4 requirements are met
Applies at least for the case where AO-SSB and OD-SSB have the same center frequency and the same positions in the same SSB burst
FFS: It is up to UE to measure both SSBs or one of them if the higher layer timeRestrictionForChannelMeasurements in CSI-ReportConfig is set to “Configured”.
OD-SSB only
FFS: Applies at least for the case where AO-SSB and OD-SSB have the different center frequencies

3GPP TSG RAN WG1 #121			R1-2504745
St Julian’s, Malta, May 19th – 23rd, 2025

Agenda Item:	9.5.1
Source: 	Moderator (LG Electronics)
Title: 	Summary #2 of on-demand SSB for NES
Document for:	Discussion and decision

Conclusion
The following combination of scenarios and cases for indicating OD-SSB are not supported in Rel-19
Scenario #3A and Case #1
Scenario #3A and Case #2
Above does not impact discussion on SSB periodicity adaptation in time domain

Agreement
Regarding the relation in terms of frequency location (i.e., center frequency) between the always-on SSB and on-demand SSB,
Alt 1: If always-on SSB is CD-SSB on a synchronization raster, the frequency location of on-demand SSB is different from the frequency location of always-on SSB.
On-demand SSB is not on sync raster
AO-SSB and OD-SSB are located in the same BWP
FFS: Additional conditions
Subject to separate UE capability
Note: UE is not required to measure both AO-SSB and OD-SSB

Agreement
Regarding the relation in terms of time location between the always-on SSB and on-demand SSB,
For the case when the center frequency locations of always-on SSB and on-demand SSB are same,
Alt Time-C: RAN1 specification has no restriction with regards to overlapping
From RAN1 perspective,
Alt Time-C1: The case that, during OD-SSB transmission, the union of AO-SSB transmission and OD-SSB transmission has a periodic time domain pattern is supported (the interval between SSB bursts is even and supported in legacy specification).
Alt Time-C2: The case that, during OD-SSB transmission, the union of AO-SSB transmission and OD-SSB transmission has a non-periodic time domain pattern is supported.
It is up to RAN4 to define requirements, if any, corresponding to both or either of Alt Time-C1 or Alt Time-C2
At least the following is supported: PBCH payload for the same SSB index (other than SFN index, half frame index) is the same for AO-SSB and OD-SSB 
FFS: Whether half frame index is the same or different for AO-SSB and OD-SSB
For the case when the center frequency locations of always-on SSB and on-demand SSB are different,
Alt Time-C: RAN1 specification has no restriction with regards to overlapping
UE assumes that frequency resources of always-on SSB are not overlapped with those of on-demand SSB in frequency domain.
AO-SSB and OD-SSB are located in the same BWP
FFS: PBCH payload for the same SSB index (other than SFN index, half frame index) should be the same for AO-SSB and OD-SSB 
NOTE: AO-SSB periodicity is not adapted
Send an LS to RAN4 to inform them of the above agreement. Final LS in R1-2501633.

Agreement
For the case where SCell with on demand SSB transmission and cell with signalling transmission have different numerology, when UE determines time instance A, the SCS to determine the value of T is down selected among the following options
Option 1: the SCS of the active DL BWP where UE receives MAC CE for on-demand SSB transmission indication
Option 2: the minimum of “the SCS of the active DL BWP where UE receives MAC CE for on-demand SSB transmission indication” and “the SCS of the active DL BWP where UE receives on-demand SSB”
Option 3: the SCS of the active UL BWP where the UE transmits ACK corresponding to the MAC-CE for on-demand SSB transmission indication

RAN1#120bis

Agreement
For the case where SCell with on demand SSB transmission and cell with signalling transmission have different numerology, adopt Option 3 to determine SCS for  for determining T
Option 3: the SCS of the active UL BWP where the UE transmits ACK corresponding to the MAC-CE for on-demand SSB transmission indication

Agreement
For the case when the center frequency locations of always-on SSB and on-demand SSB are different, at least the following is supported for QCL between AO-SSB and OD-SSB
SS/PBCH blocks with the same SSB indexes for always-on SSB and on-demand SSB are quasi co-located with respect to Doppler spread, Doppler shift, average gain, average delay, delay spread, and when applicable, spatial RX parameters.
When a signal/channel is configured to be QCLed with a SSB index, the signal/channel is QCLed with the same SSB index of always-on SSB and on-demand SSB (if transmitted) with the same QCL parameters according to existing specifications

Agreement
For a cell supporting on-demand SSB SCell operation, for configuring the number N of on-demand SSB bursts to be transmitted after on-demand SSB is indicated (i.e., od-ssb-nrofBurst),
Alt 2: The value range of od-ssb-nrofBurst is {N2 integer values}
N2= [8]
If od-ssb-nrofBurst for an on-demand SSB is NOT configured, the on-demand SSB is deactivated via MAC CE. 
If od-ssb-nrofBurst for an on-demand SSB is configured, the on-demand SSB is deactivated based on the configured value for od-ssb-nrofBurst [or via MAC CE]. 

Agreement
Upon the reception of MAC CE for deactivating on-demand SSB, UE expects that on-demand SSB is NOT transmitted from time instance B.
Time instance B’ is T slots after the slot where UE receives a signalling from gNB to deactivate on-demand SSB. If time instance B’ falls within an on-demand SSB burst, time instance B is the ending of the slot containing the last actually transmitted SSB index within the on-demand SSB burst, otherwise, time instance B = time instance B’.
As agreed in previous RAN1 meeting, the SSB time domain positions of on-demand SSB burst are configured by gNB.
As agreed in previous RAN1 meeting, the location(s) (e.g., SFN offset, half frame index) in the time domain of “possible” on-demand SSB burst and SSB position within the burst should be configured by the gNB
(Working assumption) T is not less than T_min=+1 where slot n+m is a slot indicated for PUCCH transmission with HARQ-QCK information when the UE receives MAC CE signaling to deactivate on-demand SSB ending in slot n, and  is as defined in current specification.
(Working assumption) T=T_min
RAN4 to confirm the above two working assumptions
 is based on the SCS of the active UL BWP where the UE transmits ACK corresponding to the MAC-CE for on-demand SSB transmission indication

Agreement
For a cell supporting on-demand SSB SCell operation, at least for the following parameter(s) (in addition to agreed ones), multiple candidate values can be configured (includes the case where no candidate values are configured) by RRC and the applicable value can be indicated by MAC CE for on-demand SSB transmission indication for the cell.
SSB positions within an on-demand SSB burst by using signaling similar to ssb-PositionsInBurst (i.e., od-ssb-PositionsInBurst) for the following cases
The case where center frequency of AO-SSB and OD-SSB are different
Case 1
Number N of on-demand SSB bursts to be transmitted after on-demand SSB is indicated (i.e., od-ssb- nrofBurst)
FFS: Additional restrictions

Agreement
LS to RAN4 on time instance B for on-demand SSB SCell operation is agreed. Final LS in R1-2503108.

Agreement
For a cell supporting on-demand SSB SCell operation,
Frequency of the on-demand SSB (i.e., od-ssb-absoluteFrequency) can be absent for Case #2
If absent, the center frequency of on-demand SSB is the same as that of always-on SSB.
od-ssb-PositionsInBurst, if provided, has the same bitmap structure as ssb-PositionsInBurst provided in ServingCellConfigCommon, that is od-ssb-PositionsInBurst is choice of 4-bit shortBitmap, 8-bit mediumBitmap, or 64-bit longBitmap.
od-ssb-PositionsInBurst can be absent for Case #2
If absent, od-ssb-PositionsInBurst is the same as ssb-PositionsInBurst provided in ServingCellConfigCommon.

Agreement
For a cell supporting on-demand SSB SCell operation, the following combinations of scenarios and cases are supported for indicating OD-SSB using a MAC-CE.
Scenario #3B and Case #1
In the above combinations of scenarios and cases, the MAC-CE is used only for updating the transmission parameter of a transmitted OD-SSB for the cell since the OD-SSB has been transmitted according to NW indication.
Scenario #3B and Case #2
In the above combinations of scenarios and cases, the MAC-CE is used only for updating the transmission parameter of a transmitted OD-SSB for the cell since the OD-SSB has been transmitted according to NW indication.

Agreement
For a cell supporting on-demand SSB SCell operation, for Case #1 (i.e., No always-on SSB on the cell)
UE does not expect the OD-SSB transmission indicated by RRC/MAC-CE to be deactivated while the SCell is activated.

Agreement
For a cell supporting on-demand SSB SCell operation and for Case #2 (i.e., Always-on SSB is periodically transmitted on the cell),
A CSI report configuration can be associated with 
both of AO-SSB and OD-SSB 
Which SSB to measure is up to UE implementation as long as RAN4 requirements are met
Applies at least for the case where AO-SSB and OD-SSB have the same center frequency and the same positions in the same SSB burst
FFS: It is up to UE to measure both SSBs or one of them if the higher layer timeRestrictionForChannelMeasurements in CSI-ReportConfig is set to “Configured”.
OD-SSB only
FFS: Applies at least for the case where AO-SSB and OD-SSB have the different center frequencies

3GPP TSG RAN WG1 #121			R1-2504746
St Julian’s, Malta, May 19th – 23rd, 2025

Agenda Item:	9.5.1
Source: 	Moderator (LG Electronics)
Title: 	Summary #3 of on-demand SSB for NES
Document for:	Discussion and decision

Conclusion
The following combination of scenarios and cases for indicating OD-SSB are not supported in Rel-19
Scenario #3A and Case #1
Scenario #3A and Case #2
Above does not impact discussion on SSB periodicity adaptation in time domain

Agreement
Regarding the relation in terms of frequency location (i.e., center frequency) between the always-on SSB and on-demand SSB,
Alt 1: If always-on SSB is CD-SSB on a synchronization raster, the frequency location of on-demand SSB is different from the frequency location of always-on SSB.
On-demand SSB is not on sync raster
AO-SSB and OD-SSB are located in the same BWP
FFS: Additional conditions
Subject to separate UE capability
Note: UE is not required to measure both AO-SSB and OD-SSB

Agreement
Regarding the relation in terms of time location between the always-on SSB and on-demand SSB,
For the case when the center frequency locations of always-on SSB and on-demand SSB are same,
Alt Time-C: RAN1 specification has no restriction with regards to overlapping
From RAN1 perspective,
Alt Time-C1: The case that, during OD-SSB transmission, the union of AO-SSB transmission and OD-SSB transmission has a periodic time domain pattern is supported (the interval between SSB bursts is even and supported in legacy specification).
Alt Time-C2: The case that, during OD-SSB transmission, the union of AO-SSB transmission and OD-SSB transmission has a non-periodic time domain pattern is supported.
It is up to RAN4 to define requirements, if any, corresponding to both or either of Alt Time-C1 or Alt Time-C2
At least the following is supported: PBCH payload for the same SSB index (other than SFN index, half frame index) is the same for AO-SSB and OD-SSB 
FFS: Whether half frame index is the same or different for AO-SSB and OD-SSB
For the case when the center frequency locations of always-on SSB and on-demand SSB are different,
Alt Time-C: RAN1 specification has no restriction with regards to overlapping
UE assumes that frequency resources of always-on SSB are not overlapped with those of on-demand SSB in frequency domain.
AO-SSB and OD-SSB are located in the same BWP
FFS: PBCH payload for the same SSB index (other than SFN index, half frame index) should be the same for AO-SSB and OD-SSB 
NOTE: AO-SSB periodicity is not adapted
Send an LS to RAN4 to inform them of the above agreement. Final LS in R1-2501633.

Agreement
For the case where SCell with on demand SSB transmission and cell with signalling transmission have different numerology, when UE determines time instance A, the SCS to determine the value of T is down selected among the following options
Option 1: the SCS of the active DL BWP where UE receives MAC CE for on-demand SSB transmission indication
Option 2: the minimum of “the SCS of the active DL BWP where UE receives MAC CE for on-demand SSB transmission indication” and “the SCS of the active DL BWP where UE receives on-demand SSB”
Option 3: the SCS of the active UL BWP where the UE transmits ACK corresponding to the MAC-CE for on-demand SSB transmission indication

RAN1#120bis

Agreement
For the case where SCell with on demand SSB transmission and cell with signalling transmission have different numerology, adopt Option 3 to determine SCS for  for determining T
Option 3: the SCS of the active UL BWP where the UE transmits ACK corresponding to the MAC-CE for on-demand SSB transmission indication

Agreement
For the case when the center frequency locations of always-on SSB and on-demand SSB are different, at least the following is supported for QCL between AO-SSB and OD-SSB
SS/PBCH blocks with the same SSB indexes for always-on SSB and on-demand SSB are quasi co-located with respect to Doppler spread, Doppler shift, average gain, average delay, delay spread, and when applicable, spatial RX parameters.
When a signal/channel is configured to be QCLed with a SSB index, the signal/channel is QCLed with the same SSB index of always-on SSB and on-demand SSB (if transmitted) with the same QCL parameters according to existing specifications

Agreement
For a cell supporting on-demand SSB SCell operation, for configuring the number N of on-demand SSB bursts to be transmitted after on-demand SSB is indicated (i.e., od-ssb-nrofBurst),
Alt 2: The value range of od-ssb-nrofBurst is {N2 integer values}
N2= [8]
If od-ssb-nrofBurst for an on-demand SSB is NOT configured, the on-demand SSB is deactivated via MAC CE. 
If od-ssb-nrofBurst for an on-demand SSB is configured, the on-demand SSB is deactivated based on the configured value for od-ssb-nrofBurst [or via MAC CE]. 

Agreement
Upon the reception of MAC CE for deactivating on-demand SSB, UE expects that on-demand SSB is NOT transmitted from time instance B.
Time instance B’ is T slots after the slot where UE receives a signalling from gNB to deactivate on-demand SSB. If time instance B’ falls within an on-demand SSB burst, time instance B is the ending of the slot containing the last actually transmitted SSB index within the on-demand SSB burst, otherwise, time instance B = time instance B’.
As agreed in previous RAN1 meeting, the SSB time domain positions of on-demand SSB burst are configured by gNB.
As agreed in previous RAN1 meeting, the location(s) (e.g., SFN offset, half frame index) in the time domain of “possible” on-demand SSB burst and SSB position within the burst should be configured by the gNB
(Working assumption) T is not less than T_min=+1 where slot n+m is a slot indicated for PUCCH transmission with HARQ-QCK information when the UE receives MAC CE signaling to deactivate on-demand SSB ending in slot n, and  is as defined in current specification.
(Working assumption) T=T_min
RAN4 to confirm the above two working assumptions
 is based on the SCS of the active UL BWP where the UE transmits ACK corresponding to the MAC-CE for on-demand SSB transmission indication

Agreement
For a cell supporting on-demand SSB SCell operation, at least for the following parameter(s) (in addition to agreed ones), multiple candidate values can be configured (includes the case where no candidate values are configured) by RRC and the applicable value can be indicated by MAC CE for on-demand SSB transmission indication for the cell.
SSB positions within an on-demand SSB burst by using signaling similar to ssb-PositionsInBurst (i.e., od-ssb-PositionsInBurst) for the following cases
The case where center frequency of AO-SSB and OD-SSB are different
Case 1
Number N of on-demand SSB bursts to be transmitted after on-demand SSB is indicated (i.e., od-ssb- nrofBurst)
FFS: Additional restrictions

Agreement
LS to RAN4 on time instance B for on-demand SSB SCell operation is agreed. Final LS in R1-2503108.

Agreement
For a cell supporting on-demand SSB SCell operation,
Frequency of the on-demand SSB (i.e., od-ssb-absoluteFrequency) can be absent for Case #2
If absent, the center frequency of on-demand SSB is the same as that of always-on SSB.
od-ssb-PositionsInBurst, if provided, has the same bitmap structure as ssb-PositionsInBurst provided in ServingCellConfigCommon, that is od-ssb-PositionsInBurst is choice of 4-bit shortBitmap, 8-bit mediumBitmap, or 64-bit longBitmap.
od-ssb-PositionsInBurst can be absent for Case #2
If absent, od-ssb-PositionsInBurst is the same as ssb-PositionsInBurst provided in ServingCellConfigCommon.

Agreement
For a cell supporting on-demand SSB SCell operation, the following combinations of scenarios and cases are supported for indicating OD-SSB using a MAC-CE.
Scenario #3B and Case #1
In the above combinations of scenarios and cases, the MAC-CE is used only for updating the transmission parameter of a transmitted OD-SSB for the cell since the OD-SSB has been transmitted according to NW indication.
Scenario #3B and Case #2
In the above combinations of scenarios and cases, the MAC-CE is used only for updating the transmission parameter of a transmitted OD-SSB for the cell since the OD-SSB has been transmitted according to NW indication.

Agreement
For a cell supporting on-demand SSB SCell operation, for Case #1 (i.e., No always-on SSB on the cell)
UE does not expect the OD-SSB transmission indicated by RRC/MAC-CE to be deactivated while the SCell is activated.

Agreement
For a cell supporting on-demand SSB SCell operation and for Case #2 (i.e., Always-on SSB is periodically transmitted on the cell),
A CSI report configuration can be associated with 
both of AO-SSB and OD-SSB 
Which SSB to measure is up to UE implementation as long as RAN4 requirements are met
Applies at least for the case where AO-SSB and OD-SSB have the same center frequency and the same positions in the same SSB burst
FFS: It is up to UE to measure both SSBs or one of them if the higher layer timeRestrictionForChannelMeasurements in CSI-ReportConfig is set to “Configured”.
OD-SSB only
FFS: Applies at least for the case where AO-SSB and OD-SSB have the different center frequencies

3GPP TSG RAN WG1 #121			R1-2504747
St Julian’s, Malta, May 19th – 23rd, 2025

Agenda Item:	9.5.1
Source: 	Moderator (LG Electronics)
Title: 	Summary #4 of on-demand SSB for NES
Document for:	Discussion and decision

Conclusion
The following combination of scenarios and cases for indicating OD-SSB are not supported in Rel-19
Scenario #3A and Case #1
Scenario #3A and Case #2
Above does not impact discussion on SSB periodicity adaptation in time domain

Agreement
Regarding the relation in terms of frequency location (i.e., center frequency) between the always-on SSB and on-demand SSB,
Alt 1: If always-on SSB is CD-SSB on a synchronization raster, the frequency location of on-demand SSB is different from the frequency location of always-on SSB.
On-demand SSB is not on sync raster
AO-SSB and OD-SSB are located in the same BWP
FFS: Additional conditions
Subject to separate UE capability
Note: UE is not required to measure both AO-SSB and OD-SSB

Agreement
Regarding the relation in terms of time location between the always-on SSB and on-demand SSB,
For the case when the center frequency locations of always-on SSB and on-demand SSB are same,
Alt Time-C: RAN1 specification has no restriction with regards to overlapping
From RAN1 perspective,
Alt Time-C1: The case that, during OD-SSB transmission, the union of AO-SSB transmission and OD-SSB transmission has a periodic time domain pattern is supported (the interval between SSB bursts is even and supported in legacy specification).
Alt Time-C2: The case that, during OD-SSB transmission, the union of AO-SSB transmission and OD-SSB transmission has a non-periodic time domain pattern is supported.
It is up to RAN4 to define requirements, if any, corresponding to both or either of Alt Time-C1 or Alt Time-C2
At least the following is supported: PBCH payload for the same SSB index (other than SFN index, half frame index) is the same for AO-SSB and OD-SSB 
FFS: Whether half frame index is the same or different for AO-SSB and OD-SSB
For the case when the center frequency locations of always-on SSB and on-demand SSB are different,
Alt Time-C: RAN1 specification has no restriction with regards to overlapping
UE assumes that frequency resources of always-on SSB are not overlapped with those of on-demand SSB in frequency domain.
AO-SSB and OD-SSB are located in the same BWP
FFS: PBCH payload for the same SSB index (other than SFN index, half frame index) should be the same for AO-SSB and OD-SSB 
NOTE: AO-SSB periodicity is not adapted
Send an LS to RAN4 to inform them of the above agreement. Final LS in R1-2501633.

Agreement
For the case where SCell with on demand SSB transmission and cell with signalling transmission have different numerology, when UE determines time instance A, the SCS to determine the value of T is down selected among the following options
Option 1: the SCS of the active DL BWP where UE receives MAC CE for on-demand SSB transmission indication
Option 2: the minimum of “the SCS of the active DL BWP where UE receives MAC CE for on-demand SSB transmission indication” and “the SCS of the active DL BWP where UE receives on-demand SSB”
Option 3: the SCS of the active UL BWP where the UE transmits ACK corresponding to the MAC-CE for on-demand SSB transmission indication

RAN1#120bis

Agreement
For the case where SCell with on demand SSB transmission and cell with signalling transmission have different numerology, adopt Option 3 to determine SCS for  for determining T
Option 3: the SCS of the active UL BWP where the UE transmits ACK corresponding to the MAC-CE for on-demand SSB transmission indication

Agreement
For the case when the center frequency locations of always-on SSB and on-demand SSB are different, at least the following is supported for QCL between AO-SSB and OD-SSB
SS/PBCH blocks with the same SSB indexes for always-on SSB and on-demand SSB are quasi co-located with respect to Doppler spread, Doppler shift, average gain, average delay, delay spread, and when applicable, spatial RX parameters.
When a signal/channel is configured to be QCLed with a SSB index, the signal/channel is QCLed with the same SSB index of always-on SSB and on-demand SSB (if transmitted) with the same QCL parameters according to existing specifications

Agreement
For a cell supporting on-demand SSB SCell operation, for configuring the number N of on-demand SSB bursts to be transmitted after on-demand SSB is indicated (i.e., od-ssb-nrofBurst),
Alt 2: The value range of od-ssb-nrofBurst is {N2 integer values}
N2= [8]
If od-ssb-nrofBurst for an on-demand SSB is NOT configured, the on-demand SSB is deactivated via MAC CE. 
If od-ssb-nrofBurst for an on-demand SSB is configured, the on-demand SSB is deactivated based on the configured value for od-ssb-nrofBurst [or via MAC CE]. 

Agreement
Upon the reception of MAC CE for deactivating on-demand SSB, UE expects that on-demand SSB is NOT transmitted from time instance B.
Time instance B’ is T slots after the slot where UE receives a signalling from gNB to deactivate on-demand SSB. If time instance B’ falls within an on-demand SSB burst, time instance B is the ending of the slot containing the last actually transmitted SSB index within the on-demand SSB burst, otherwise, time instance B = time instance B’.
As agreed in previous RAN1 meeting, the SSB time domain positions of on-demand SSB burst are configured by gNB.
As agreed in previous RAN1 meeting, the location(s) (e.g., SFN offset, half frame index) in the time domain of “possible” on-demand SSB burst and SSB position within the burst should be configured by the gNB
(Working assumption) T is not less than T_min=+1 where slot n+m is a slot indicated for PUCCH transmission with HARQ-QCK information when the UE receives MAC CE signaling to deactivate on-demand SSB ending in slot n, and  is as defined in current specification.
(Working assumption) T=T_min
RAN4 to confirm the above two working assumptions
 is based on the SCS of the active UL BWP where the UE transmits ACK corresponding to the MAC-CE for on-demand SSB transmission indication

Agreement
For a cell supporting on-demand SSB SCell operation, at least for the following parameter(s) (in addition to agreed ones), multiple candidate values can be configured (includes the case where no candidate values are configured) by RRC and the applicable value can be indicated by MAC CE for on-demand SSB transmission indication for the cell.
SSB positions within an on-demand SSB burst by using signaling similar to ssb-PositionsInBurst (i.e., od-ssb-PositionsInBurst) for the following cases
The case where center frequency of AO-SSB and OD-SSB are different
Case 1
Number N of on-demand SSB bursts to be transmitted after on-demand SSB is indicated (i.e., od-ssb- nrofBurst)
FFS: Additional restrictions

Agreement
LS to RAN4 on time instance B for on-demand SSB SCell operation is agreed. Final LS in R1-2503108.

Agreement
For a cell supporting on-demand SSB SCell operation,
Frequency of the on-demand SSB (i.e., od-ssb-absoluteFrequency) can be absent for Case #2
If absent, the center frequency of on-demand SSB is the same as that of always-on SSB.
od-ssb-PositionsInBurst, if provided, has the same bitmap structure as ssb-PositionsInBurst provided in ServingCellConfigCommon, that is od-ssb-PositionsInBurst is choice of 4-bit shortBitmap, 8-bit mediumBitmap, or 64-bit longBitmap.
od-ssb-PositionsInBurst can be absent for Case #2
If absent, od-ssb-PositionsInBurst is the same as ssb-PositionsInBurst provided in ServingCellConfigCommon.

Agreement
For a cell supporting on-demand SSB SCell operation, the following combinations of scenarios and cases are supported for indicating OD-SSB using a MAC-CE.
Scenario #3B and Case #1
In the above combinations of scenarios and cases, the MAC-CE is used only for updating the transmission parameter of a transmitted OD-SSB for the cell since the OD-SSB has been transmitted according to NW indication.
Scenario #3B and Case #2
In the above combinations of scenarios and cases, the MAC-CE is used only for updating the transmission parameter of a transmitted OD-SSB for the cell since the OD-SSB has been transmitted according to NW indication.

Agreement
For a cell supporting on-demand SSB SCell operation, for Case #1 (i.e., No always-on SSB on the cell)
UE does not expect the OD-SSB transmission indicated by RRC/MAC-CE to be deactivated while the SCell is activated.

Agreement
For a cell supporting on-demand SSB SCell operation and for Case #2 (i.e., Always-on SSB is periodically transmitted on the cell),
A CSI report configuration can be associated with 
both of AO-SSB and OD-SSB 
Which SSB to measure is up to UE implementation as long as RAN4 requirements are met
Applies at least for the case where AO-SSB and OD-SSB have the same center frequency and the same positions in the same SSB burst
FFS: It is up to UE to measure both SSBs or one of them if the higher layer timeRestrictionForChannelMeasurements in CSI-ReportConfig is set to “Configured”.
OD-SSB only
FFS: Applies at least for the case where AO-SSB and OD-SSB have the different center frequencies