3GPP TSG-RAN WG1 Meeting #121	R1-2503220
Malta, MT, May 19th – May 23rd, 2025

Agenda Item:	9.4.1
Source:	Ericsson
Title:	Modulation aspects for Ambient IoT
Document for:	Discussion, Decision
1	

Conclusion
In the previous sections we made the following observations:
Observation 1	It is feasible to generate OOK-4 using either CP-OFDM (with an optimization algorithm, e.g., LS) or DFT-S-OFDM (with DFT precoding) for any given M value.

Based on the discussion in the previous sections we propose the following:
Proposal 1	The specification needs to avoid imposing unnecessary restrictions on reader implementation choices. For example, Step 3 could be implemented using an N-point DFT/LS equation.
Proposal 2	The content of padding is up to reader implementation and transparent to device.
Note: The timeline determination of any timing relationship refers to the start of the padding.
Proposal 3	Method Type 2 Alt 1-1 (Candidate 3) is not supported (since it restricts scheduling and degrades spectral efficiency due to parity chips).
Proposal 4	Support Method Type 1 for PRDCH. There is no need to pursue any additional CP handling design.
Proposal 5	M chips correspond to M ON/OFF segments within one A-IoT OFDM symbol before CP insertion.
Proposal 6	For M values of {2, 6, 12, 24} in the Table 6.1.1.4-1 (as per TR38.769), the associated minimum Btx,R2D value of PRBs is updated as followings:

3GPP TSG RAN WG1 Meeting #121	R1-2503224
St. Julian’s, Malta, May 19 – May 23, 2025
Agenda Item:	9.4.1
Source:	Futurewei
Title:	Discussion on modulation aspects for A-IoT physical channel
Document for:	Discussion and Decision 

Conclusion

Observation 1: Compared to Option3, Option 1 provides the detection performance improvement of about 2 dB for M=24, and over 10 dB for M=32.
Observation 2: Option 1 with the last two chips set to “OFF” provides better performance compared to setting the last two chips to “ON”.
Observation 3: No CP handling is needed for SIP.
Observation 4: CAP provides two low-to-high transitions and two high-to-low transitions. 
Observation 5: The OFDM symbol that has CAP will need CP handling. 
Observation 6: For M=2 no CP handling is needed. 
Observation 7: For M=6, 12 and 24, the CP insertion part must be OFF to maintain the transition timing accuracy for CAP.  
Observation 8: For the padding Alt 1b is preferred over Alt 1a. 
Observation 9: For the padding it is beneficial to the device if Alt 2 can be agreed.  

Proposal 1: For supported M values > 12, adopt M2-1-1 Candidate 3 for CP handling for at least PRDCH.
Proposal 2: The M value derived from CAP is at least used for the beginning of PRDCH 
Proposal 3: For the OFDM symbol where the CAP is present, the last two chips are set to be OFF for M=6, 12 and 24.
Proposal 4: Consider  chips with equal durations  within the OFDM symbol, not including the CP duration, i.e.,  .

3GPP TSG-RAN WG1 Meeting #121	R1-2503294
St Julian’s, Malta, May 19-23, 2025

Agenda Item:	9.4.1
Source:	Huawei, HiSilicon
Title:	Physical channels design on modulation
Document for:	Discussion and Decision 

Conclusions
In this contribution, the physical channels design on modulation for Ambient IoT are discussed and following observations and proposals are made accordingly.
Observation 1: For M = 2, 6 and 12, additional CP handling design is not needed for the OFDM symbol contains CAP. Negligible performance impacts are expected for the SIP and CAP detection. 
Observation 2: For M = 24, additional CP handling design Candidate 3 of M2-1-1 is needed for the OFDM symbol containing CAP. It will avoid the problem of misunderstanding the CP part as the CAP and the false detection of the PRDCH start time. 
Observation 3: At least the last transition edge (one pair of [ON OFF] or [OFF ON]) with a fixed position is required in the last OFDM symbol including the padding content in order to provide a reference transition edge to ensure the OFDM symbol boundary with a limited time error.
Observation 4: At least the last transition edge with a fixed position is provided by the end chips of the last OFDM symbol to enable the smallest timing error accumulated for the timeline.
The end 3 chips of the last OFDM symbol are [OFF ON ON] for M = 24 
The end 2 chips of the last OFDM symbol are [OFF ON] or [ON OFF] for M = 2, 6, 12
Proposal 1: For PRDCH CP handling of M = 24, Candidate 3 of M2-1-1 is supported.
Proposal 2: For R2D, the chip duration is equal to one OFDM symbol length without CP divided by M i.e. (1/SCS)/M. For SIP, the number of (effective) chips is used, instead of M (decided in 9.4.3).
Proposal 3: For R2D padding, the end chip(s) of the padding content shall follow the CP handling method determined in section 2.1. For M = 24, the end 2 chips of the padding content shall be two “ON” chips.
Proposal 4: The timeline determination of any relationship refers to the end of padding (if any) or the end of the last OFDM symbol of R2D transmission.
Proposal 5: R2D padding with Alt 1a or with Alt 2 in RAN1#120bis agreement is supported. 
If Alt 1a is supported, constraints need to be added that at least the provided last transition edge is required with a fixed position which is located in the last 1 or 1/2 OFDM symbol including the padding content, as well as to require the last two chips are [ON ON] for CP handling Option 3 when M = 24.
If Alt 2 is supported, the end chips of the last OFDM symbol including the padding content is [OFF ON ON] for M = 24 and [OFF ON] or [ON OFF] for M = 2, 6 and 12. Note: The other chips of padding do not require specification.

3GPP TSG RAN WG1 #121	R1-2503299
St Julian's, Malta, May 19th - 23rd, 2025

Source:	Nokia
Title:	AIoT Physical channels design - modulation aspects
Agenda item:	9.4.1
Document for:	Discussion and Decision

Conclusion
In this contribution we have made the following observations and proposals:

3GPP TSG RAN WG1 meeting #121                                   R1-2503311
St Julian's, Malta, May 19th - 23rd, 2025

Source: 	ZTE Corporation, Sanechips
Title:	Discussion on Ambient IoT modulation
Agenda Item:	9.4.1
Document for:	Discussion and decision

Conclusion
In this contribution, we discuss the Ambient IoT modulation and have the following observations and proposals.
Observation 1: It is observed that for supported M values > 12, i.e. M=24, a false transition edge is introduced during the CP if no additional CP handling design, while a constant power level is kept during the CP if the candidate 3 of M2-1-1 is used as the additional CP handling design. 
Observation 2: Under the case of TBS=96bits, for M=24, Candidate 3 of M2-1-1 achieves BLER performance of SNR=21dB@10% BLER, while Alt M1-1 has an error floor.
Observation 3: For R2D, the chip duration is not an integer of the time unit. The reason is that IDFT points of  can not be evenly divided by the supported M values, i.e. 6, 12 and 24.
Observation 4: For R2D, the IDFT size (N=2^n) can not be divided by M values, i.e. M=6, 12 and 24. For example, assuming N=128 and M=24, the number of samples of each chip is 5 or 6, where slight sample errors can lead to an additional transition edge or a chip deletion.

Proposal 1: Candidate 3 of M2-1-1 is proposed to be used for CP handling for M=24. 
Proposal 2: Alt 1b is adopted due to less latency.
Proposal 3: Considering the R2D detection performance and the relationship between  and , there are  consecutive chips each of duration  and  consecutive chips each of duration  in an OFDM symbol. 

3GPP TSG RAN WG1 #121	R1-2503358
St Julian’s, Malta, May 19th – 23rd, 2025

Source:	vivo
Title:	Remaining issues on Modulation Aspects of Physical Channels Design
Agenda Item:	9.4.1
Document for:	Discussion and Decision

Conclusion
In this contribution, we discuss the remaining issue for modulation aspects of physical channels design. And we have the following observations and proposals.
Observation 1: Candidate 3 of method type 2 does not provide performance gain compared with method type 1, while still requires higher overhead and increases additional reception complexity.
Observation 2: From AIoT device perspective, device can identify the end of PRDCH transmission per RAN2 agreements by the MAC header, which is neither encrypt nor channel coded, before the end of PRDCH transmission.
Observation 3: How accurately the device can determine the last OFDM symbol boundary is not a big issue, additional time accuracy caused by determining the last OFDM symbol boundary is marginal in timeline determination.
Observation 4: To ensure the same chip length from signal generation perspective, it is preferred to use N’=M*L. 
Observation 5: For simplified signal generation based on DFT-S-OFDM, it is preferred to use .
Observation 6: Larger pre-DFT size with truncation can achieve more flattened ON/OFF chips compared with small pre-DFT size without truncation.
Observation 7: The pre-DFT output length N’ can be greater than X, and the output of the pre-DFT can be truncated to fit Tx BW with X subcarriers in step 4.
Observation 8: If the output of the pre-DFT is directly mapped to subcarriers without reordering, the ‘center frequency component’ is actually mapped to lowest frequency of the RB resource, which may lead to the OOK chip not flattened, and not desired for edge detection for Manchester coded R2D transmission.
Observation 9: Re-ordering of the pre-DFT/truncation (if used) output, i.e., DFT shift, is needed in step 4 to make sure the direct current in baseband shifted to the center of frequency resource.
Proposal 1: M value for PRDCH is same as that for CAP part in R2D preamble.
Proposal 2: For M=24, support option 3 that is RAN1 will not further pursue additional CP handling design.
Proposal 3: R2D chip length is defined as .
Proposal 4: Alt 1a is supported, when the generated number of chips for the R2D transmission does not fully occupy the last OFDM symbol, and the timeline determination of any timing relationship refers to the end of padding.
Proposal 5: In an information Annex of specification, all five steps can be captured with further detailed description for Step 3, Step 4 and Step 5, and Annex is not considered as normative specification.
In step 3, Annex reflects N’ = M*L which fulfills 
In step 4, Annex reflects following
Step 4.1: FFT shift operation for output of step 3, i.e., reordering of output of step 3
Step 4.2: Truncate N’ to X, i.e., first and last (N’-X)/2 elements are dropped if N’>X
Adopt the TP for information Annex in TS 38.291 in R1-2503358.

3GPP TSG RAN WG1 #121                                                                R1-2503515
St Julian’s, Malta, May 19th – 23rd, 2025

Agenda Item:	9.4.1
Source:	Spreadtrum, UNISOC
Title:	Discussion on modulation aspects of physical channels design for Ambient IoT
Document for:	Discussion and decision

Summary
In the contribution, we provides our view on the ambient IoT device architectures, and propose that,
Proposal 1: Alt 1a for R2D padding should be supported, where the timeline determination of any timing relationship refers to the end of padding.
Observation 1: Ambient IoT device can be aware of the end of padding or the last OFDM symbol boundary by counting the chip, leveraging the inferred M value.
Proposal 2: The limitations for waveform generation, i.e., the sub-bullet of each step in the above agreement, should be considered to be captured into TS, and the exact value of L, N, and N’ should totally up to reader implementation without any spec impact.
Proposal 3: Candidate 3 of M2-1-1 should be supported for R2D CP handling with M = 24.
Proposal 4: if Alt M2-1-1 is supported with M = 24, it should be always to be supported no matter high or low TBS case.
Proposal 5: The pre-processing process for inserting the padding bits between every 22 information bits (after line coding) should be captured into TS.
Proposal 6: The R2D chip length in one OFDM symbol is defined as 1 / (SCS*M).

3GPP TSG RAN WG1 #121                                            R1-2503536
St Julian's, Malta, May 19th-23rd, 2025

Source:	TCL
Title:	Discussion on modulation aspects for Ambient IoT physical design
Agenda Item:	9.4.1
Document for:	Discussion and Decision

Conclusion
In this contribution, we provide our views on the feasibility and required functionalities of physical modulation for AIoT. The observations and proposals are listed as below:

Observation 1: For M=1, OOK-4 can be generated by CP-OFDM and DFT-OFDM, and for M>1, OOK-4 can be generated by DFT-OFDM.

Observation 2: Limited by device 1’s detection capability, before N’-points DFT performed, concentrated frequency spectrum could impact time domain ON/OFF chips with M*L samples , e.g., no flattened waveform or with higher PAPR, which is not suitable edge detection at device side.

Observation 3: Modulation like QAM/pi/2-BPSK/BPSK, scrambling of ON/OFF chips or sampling points, different sequence types or length, and predefined matrix or vector or sequence could be considered for handling concentrated frequency spectrum related problems.

Observation 4: Regardless of CAP length, padding filling may be needed if CAP is also needed to align with OFDM symbol n+1 and ensure SIP duration with one OFDM symbol. 

Observation 5: Padding filling may be needed for CAP if PRDCH transmission needs to align OFDM symbol boundary.

Observation 6: For option 1, it requires the last 2 out of M OOK chip at the end of OFDM symbol are always ON, which may add other efforts in Rel-19 specification phase.



Proposal 1: For R2D, including CAP of R-TAS and PRDCH, the set of M values is {2, 6, 12, 24} in Rel-19. 

Proposal 2: Each ON/OFF chip with randomized amplitude or phase after step 1 could be considered for handling concentrated frequency spectrum related problems.

Proposal 3: Consider potential methods for randomizing amplitude or phase of ON/OFF chip, e.g., modulation like QAM/pi/2-BPSK/BPSK, scrambling of ON/OFF chips or sampling points, different sequence types or length, and predefined matrix or vector or sequence, etc.

Proposal 4: How to solve signal distortion because of truncation operation for DFT-s-OFDM operation should be considered in WI phase.

Proposal 5: Consider combination of scrambling and adding redundant sequence to resist on the impact of truncation. 

Proposal 6: For R2D padding filling, only Alt 1b should be supported in Rel-19.

Proposal 7: Support option 3 when M values>12:
Option 3: RAN1 will not further pursue additional CP handling design

Proposal 8: Support following methods for R2D chip calculation,
 , where C represents a R2D chip duration
, where,  is a floating chip duration and FFS: 

3GPP TSG RAN WG1 #121		R1-2503566
St Julian’s, Malta, May 19th – 23th, 2025 
Agenda item:	9.4.1
Source:	Samsung
Title:	Views on Physical channels design – modulation aspects
Document for:	Discussion and decision

Conclusion
In this contribution, we discussed modulation aspects for physical channel design with the following observations and proposals:
Observation 1: Alt M1-1 is not appropriate for large M values, e.g. M=24. There exists a potential offset between practical CP position and device expected CP position, due to not distinguishing LCP/NCP and also SFO impact. With M=24, a typical sampling offset of 25% ~ 67% of code chip length are observed, which may severely impacts R2D reception performance.
Observation 2: Alt M1-2 is not appropriate for M = 24. The difference between LCP/NCP and two line code chips has only 0.67~1.67 sampling points time length, thus become non-distinguishable at receiver side.
Observation 3: With M=24, the performance of Method type 1 degrades with TBS increasing, due to increased number of residual error of CP removal per OFDM symbol. Compared with small message size of TBS=20 bits, the SNR threshold of TBS=200 bits increases around 7 dB at 10% target BLER, and extremely increases at 1% target BLER.
Observation 4: With M=24, TBS=20 bits, Option 1 outperforms 2.1 dB than Option 3 at 10% BLER target. With M=24, TBS=200 bits, Option 1 outperforms 8.4 dB than Option 3 at 10% BLER target. 
Observation 5: Padding option Alt 1a and Alt 1b are not preferable given that they are self-contradicting. Also, implementation-based option will make the device determination more complex and erroneous compared to a defining padding signal. 
Observation 6: Specifying padding signal is preferable given (i) easiness in device implementation, (ii) clarity in determining the timing relationship, and (iii) testability. 
Observation 7: The remaining issues for D2R modulation including 1) a set of supported D2R chip lengths and 2) a signaling for indicating D2R chip length can be discussed in AI 9.4.2 and AI 9.4.4.
Proposal 1: For supported M values >12, Option 1: the last 2 out of M OOK chips at the end of an OFDM symbol are always ‘ON’ is applied for R2D transmissions at least for PRDCH.
Proposal 2: When the generated number of chips for the R2D transmission do not fully occupy the last OFDM symbol, padding is used based on one of the following options:
Option 1) zero-bit padding or one-bit padding before CRC attachment
Option 2) zero-chip padding or alternation of zero-chip and one-chip padding after CRC attachment
Proposal 3: When PRDCH is attached with postamble and padding is performed, the end of postamble is aligned with the next OFDM symbol boundary. 
Proposal 4: CAP using the same M value as the following PRDCH is the most simple and precise method for a device to acquire chip length without any unnecessary steps. 
Proposal 5: For PRDCH chip duration, 
For non-CP part, chip duration is denoted as . 
Within CP part, the R2D OOK chip duration can be larger or less than  after CP insertion by copying code chip(s) in the end of an OFDM symbol. 
Definition of chip duration for R2D preamble is depending on preamble design and discussed separately.



References:
TR 38.769-201, Study on solutions for ambient IoT (Internet of Things)
RP-250896, New Work Item: Solutions for Ambient IoT (Internet of Things) in NR, 3GPP TSG RAN Meeting #107, Incheon, Korea, March 12th-14th, 2025
RAN1 Chair’s Notes, 3GPP TSG RAN WG1 #120bis, Wuhan, China, April 7th – 11nd, 2025.
RAN1 Chair’s Notes, 3GPP TSG RAN WG1 #120, Athens, Greece, February 17th – 21st, 2025.

3GPP TSG RAN WG1 #121          						R1- 2503703
Malta, Malta, May 19th – 23rd, 2025

Source:	Tejas Networks Ltd.
Title:	Discussion on modulation aspects for A-IoT physical channel
Agenda item:	9.4.1
Document for:     Discussion and Decision

Conclusion
This work includes the modulation aspects of A-IoT Physical Channel, estimation of optimum M-value for R2D signal generation, and CP handling for R2D CAP. We have made the following observations and proposals related to the above-mentioned aspects of A-IoT:

Observation 1: The data rate increases with M value. For M = 24, the data rate is above 100kbps.
Proposal 1: The Core network can provide the data rate and latency as an additional information to the Base station. The M value can be decided based on the required data rate and latency.
Observation 2: CAP duration of 1 OFDM symbol ensures sufficient difference between the PRDCH chip duration and CAP chip duration. CAP chip duration is half of the ON/OF chip duration of PRDCH.  
Proposal 2: We propose a fixed CAP duration of 1 OFDM symbol. 
Proposal 3: The CP part of CAP can be handled in two ways:
Option 1: Add the last part of OFDM symbol to CP
Option 2: Entire CP duration is OFF
Proposal 4: The device my detect the CAP duration between two falling edges or between the first falling edge and next rising edge after the end of SIP.

Conclusion
In this contribution, the following proposals and observations have been made:
Proposal 1: Support only Method Type 1 for all M.
Proposal 2: Define chip duration as  .

3GPP TSG RAN WG1 #121	R1-2503734
St Julian's, Malta, May 19th - 23rd, 2025

Source:	Ofinno
Title:	Views on Physical channels design – modulation aspects for AIoT
Agenda item:	9.4.1
Document for:	Discussion and Decision

Conclusions
In this paper we make the following observations and proposals: 
Observation 1: The A-IoT device determines the M value of the PRDCH based on the corresponding CAP. 
Proposal 1: For the CAP the set of M values is {2, 6, 12, 24} and the M value of the CAP is the same as the M value of the associated PRDCH.  
Observation 2: The ratio between the difference of the normal CP and the long CP length and the chip duration is ~19%. 
Observation 3: Relying on CP handling method type 1 for M > 12 increased the device complexity. 
Proposal 2: For PRDCH, M > 12 support Candidate 3 of M2-1-1.
Proposal 3: Support using Candidate 3 of M2-1-1 for the CAP for all M values.      
Proposal 4: For padding, support Alt 1b: The content of padding is up to reader implementation and transparent to device. 
FFS: impact on Toffset1 and Toffset2. 

3GPP TSG RAN WG1 #121		R1-2503793
St Julian’s, Malta, May 19th – 23rd, 2025
  
Source:             CATT
Title:                  Ambient IoT physical channel design and modulation
Agenda Item:    9.4.1
Document for:  Discussion and Decision	

Conclusion
In this contribution, the general aspects of physical layer design for NR Ambient IoT communication system are discussed. We have the following observations and proposals:
Proposal 1: For M value is larger than 12, the Option 3 that RAN1 will not further pursue additional CP handling design should be supported.
Observation 1: Since the A-IoT D2R does not have the orthogonality for the UL NR signals, NR A-IoT R2D signal should not need to maintain a strict orthogonality with legacy DL NR signal.
Observation 2: For Method Type 2-M2-2, existing mechanisms can resolve or mitigate the inter-system interference between the A-IoT system and the NR system as follows:
Solution 1: The NR DL/UL signal and the A-IoT R2D/D2R signal can be transmitted using TDM.
Solution 2: The legacy NR UE and A-IoT devices can be deployed in different deployment scenarios, such as deploying the A-IoT reader/devices indoor while the NR UEs outdoor.
Solution 3: Using large guard band to mitigate the interference between A-IoT system and NR system.
Solution 4: gNB could utilize some existing mechanisms, such as using the pulse shaping filter, to minimize the interference from the R2D signal/channel to the adjacent NR channels during the transmission.
Observation 3: The comparison and analysis for the candidates of CP handling in following table should be considered for the CP handling method determination.

Proposal 2: Method Type 2-M2-2, which extends the legacy OFDM symbol duration without NR CP operation, should be considered for R2D signal transmission due to its lower complexity and more efficient spectrum resource utilization in Rel-20.
Observation 4: The device can obtain the last OFDM symbol boundary based on the CAP in R-TAS and the TBS indication.
Proposal 3:  The Alt 1a should be supported, in which the content of padding is up to reader implementation and transparent to device. The timeline determination of any timing relationship refers to the end of padding.
Proposal 4: For the CAP of R-TAS, the set of M values should be {2, 6, 12, 24}.
Proposal 5: The chip duration of the R-TAS and the PRDCH should be the same, and the reader only needs to indicate a unique R2D chip duration for the PRDCH derived from the detection of the R-TAS.
Proposal 6: The D2R chip duration of {133.33, 66.67, 33.33, 16.67, 11.11, 8.33, 5.56, 4.17, 2.78, 2.08, 1.39, 1.04, 0.69, 0.52} μs should be supported for Rel-19 A-IoT.
Proposal 7: The D2R bit duration could support both of 1.39μs and 1.04μs for Rel-19 A-IoT. If one D2R bit duration needs to be down-selected between 1.39μs and 1.04μs, D2R bit duration of 1.39μs should be supported.
Observation 5: For the D2R channel by a small frequency shift, the device needs to know any two of the bit duration Tb, D2R chip duration and SFS factor R.
Proposal 8: SFS factor R could be included for the indication of frequency channel in the R2D control information.
Proposal 9: To indicate D2R chip duration Tchip and SFS factor R, there are two schemes can be considered
Option a: The D2R chip duration is implicitly indicated by deriving from the control signaling of bit duration Tb and SFS factor R. 
Option b: The D2R chip duration and SFS factor R are explicitly indicated for the D2R transmission.
Proposal 10: When the D2R chip duration is implicitly indicated by deriving from the control signaling of bit duration Tb and SFS factor R, three potential Options for D2R transmission indication should be considered, and the Option a-3 could be preferable for flexible indication.
Option a-1: The value/index of the bit duration Tb is explicitly indicated based on the pre-defined table, in which it also pre-defines the relationship of the bit duration Tb and corresponding chip duration Tchip and SFS factors R. 
Option a-2: The value/index of the bit duration Tb and the SFS factor R are jointly explicitly indicated for D2R transmission via the control information of PRDCH. The R could be expressed as Rmax for FDMed Msg1 transmission, while it could be the dedicated R value for Msg3 or CFRA.
Option a-3: The value/index of the bit duration Tb is explicitly indicated and the corresponding subset of the R values are also indicated via the control information of PRDCH or based on the pre-defined table.
Proposal 11: When the explicit indication of D2R chip duration is supported, the following two potential options should be considered and Option b-1 is preferable due to simple implementation.
Option b-1: The D2R chip duration index and the SFS factor R are carried in the control information in PRDCH. The D2R bit duration and corresponding R value(s) could be derived via the indicated chip duration and the R value (e.g. maximum/minimum R value) according to the predefined R value set or TBS related information.
Option b-2: The joint indication of the D2R chip duration and subset of R values for D2R transmission is carried in the control information in PRDCH. 
Observation 6: The phase discontinuity issue of OOK demodulation by the reader using the BPSK demodulation method after DC removal would severely degrade the OOK demodulation performance if the reader does not know the D2R waveform is OOK or BPSK.  
Proposal 12: In order not to degrade the OOK demodulation performance, the reader should be aware of the modulation scheme of OOK or BPSK for the D2R transmission.
Proposal 13: For modulation quality, a less stringent EVM requirement should be defined for Device 1 than that in NR, which can be determined in RAN4. 
Proposal 14: The following working assumption could be confirmed: 
For indicating the payload size (i.e. TBS-like) for PDRCH transmission with variable size:
7 bits for byte-level D2R payload size indication
Proposal 15: The TBS tables should be introduced for simple indication of TBS and the corresponding TTI under the different chip duration/data rate, which are aligned with the NR time domain resource assignment, i.e. slot.
Proposal 16: The 3 bits TBS indication table as follows should be considered for PRDCH.

3GPP TSG RAN WG1 #121	R1-2503831  
St Julian’s, Malta, May 19th – 23th, 2025

Source: 	CMCC
Title:	Discussion on modulation aspects of physical channel design
Agenda item:	9.4.1
Document for:	Discussion/Decision

Conclusions 
In this contribution, we give our consideration on modulation aspects of A-IoT physical layer design, and the following proposals and observations are made:
Proposal 1: For CP handling which retains subcarrier orthogonality, Method Type 1 is supported for all M values.
Proposal 2: For R-TAS, the related CP handling from device side can be up to implementation. 
Proposal 3: In R2D, a chip
Corresponds to one modulated symbol for OOK-4.
Chip duration = (1/M) × {OFDM symbol duration excluding CP part}.
Proposal 4: When the generated number of chips for the R2D transmission does not fully occupy the last OFDM symbol, padding is used.
Alt 1b: The content of padding is up to reader implementation and transparent to device.
The timeline determination of any timing relationship refers to the start of the padding.
Proposal 5: For a Manchester encoded OOK-4 signal, the following signal generation procedures can be used as an example for reader.
Step 1: Generation of the time-domain signals 
For M value, assuming the time-domain signal is ,where .
Resample the time-domain signal  to N points  , where  and N is the FFT size.
Step 2: transform to frequency domain
DFT transform of the time-domain signal  into , where ，
FFT shift of  into  . Note that now the DC is in the middle element of vector , and , where  
Step 3: Remove the components that outside the transmission bandwidth
Assuming the transmission bandwidth is K FFT points (e.g., BW/15kHz), nulling all elements (set to zero) except  to 
Cyclic shift  points to the left so that the DC is now at the center of the  to  point. The output signal is written as 
FFT shift of the . The output is written as  
Step 4: generate time-domain transmitted OOK-4 signal
IFFT of . The output is written as 
Insert CP for signal z'
Adding Tx Filter (optional) so that the CP burst (if exist) can be suppressed.

3GPP TSG RAN WG1 #121			R1-2503882
St Julian’s, Malta, 19th - 23rd May 2025

Agenda Item:	9.4.1
Title:          Discussion on modulation aspects for Ambient IoT
Source:        Xiaomi
Document for:	Decision

Conclusion
In this contribution, we provide the following proposals and observations.
Observation 1: Option 1 will result in a reduction of transmission efficiency, which contradicts the initial rationale for selecting M=24. 
Observation 2: Option 1 will introduce extra protocol complexity without providing clear benefits, making it an impractical choice.
Observation 3: The padding content is determined by the reader implementation and may exhibit a pattern similar to or identical to SIP, which could result in the device erroneously recognizing data, CP, or padding chips as SIP.
Proposal 1: Support option 3 for supported M values > 12 for PRDCH.
RAN1 will not further pursue additional CP handling design
Proposal 2: RAN1 should not further pursue additional CP handling design for R-TAS.
Proposal 3: For R2D, support the table based on the Table 6.1.1.4-1 (as per TR38.769) as followings:
Proposal 4: For R2D, CAP using same M values set as PRDCH should be supported, where the M value for CAP is identical to that of PRDCH.
Proposal 5: For R2D chip duration, the length of R2D chip duration (denoted as ‘C’) in one OFDM symbol is defined as:
C = (1/SCS)/M
Proposal 6: Support specifying the detailed content of padding
Note: the timeline determination of any timing relationship refers to the end of padding.
Proposal 7: Support specifying the details of step 1 and step 5 for waveform generation, and whther/how other aspects of specification are determined is up to RAN4.

3GPP TSG RAN WG1 #121	R1-2503924
St Julian's, Malta, 19 - 23 May, 2025

Agenda Item:	9.4.1
Source:	NEC
Title:	Discussion on modulation aspects of ambient IoT
Document for:	Discussion and Decision
1	

Conclusion
In this contribution, we give our views on modulation aspects of ambient IoT. We propose that:
Proposal 1: For CP handling when M values > 12, Option 1 is supported, i.e., the last 2 out of M OOK chips at the end of an OFDM symbol are always ‘ON’.
Proposal 2: Support Alt 2 to specify content of padding to aid the detection of end of padding.
Proposal 3: Contents of padding can be all “ON” chips to violate Manchester code.

3GPP TSG RAN WG1 #121			R1-2504007
St Julian’s, Malta, 19th – 23rd May 2025

Source:	Panasonic
Title: 	A-IoT Physical Channels Design on Modulation Aspects
Agenda Item:		9.4.1
Document for:	Discussion, Decision

Conclusion 
In this contribution, the followings proposals are made: 
Proposal 1: For CP handling when M values >12, we prefer to support Option 3 that RAN1 will not further pursue additional CP handling design.
Proposal 2: We are also ok with Option 1 if performance gain is larger than 0.33 dB (the 2 M OOK padding chips increased PRDCH length by (24+2)/24 =8 %, roughly 0.33dB).
Proposal 3: Either Alt 1a or Alt 2 is ok for the R2D padding. Alt 1b should be avoided.
Proposal 4: As CP part is to be discarded by device, support the length of R2D chip duration to be defined as C = (1/SCS)/M at least for Method Type 1

3GPP TSG RAN WG1 #121			R1- 2504046
St Julian’s, Malta, May 19th – 23th, 2025

Agenda item:		9.4.1
Source:	China Telecom
Title:	Discussion on physical channels design about modulation aspects for Ambient IoT
Document for:		Discussion

Conclusion
In this contribution, we have the following proposals:
Proposal 1: For R2D, support the same M values set as PRDCH for CAP.
Proposal 2: For CP handling which retains subcarrier orthogonality, support to remove CP at device without specified transmit-side.
Using Alt M1-1 and/or Alt M1-2 is up to device implementation as per TR 38.769 for all corresponding M values.

Proposal 3: The CP handling which does not retain subcarrier orthogonality is not considered in Rel-19.
Proposal 4: For CP handling of A-IoT R2D transmission, only normal CP is supported.
Proposal 5: If any part of R2D preamble needs CP handling, the same CP handling solution applies for both R2D preamble and PRDCH.
Proposal 6: When the generated number of chips for the R2D transmission does not fully occupy the last OFDM symbol, padding is used.
The content of padding is up to reader implementation and transparent to A-IoT device.
From reader side, the timeline determination refers to the end of the padding.
From device side, the timeline determination refers to the start of the padding.

Proposal 7: For R2D chip duration, the length of R2D chip duration (denoted as ‘C’) in one OFDM symbol is defined as: C = (1/SCS)/M.

3GPP TSG RAN WG1 #121		R1-2504088
St Julian’s, Malta, May 19th – 23rd, 2025
Agenda Item:	9.4.1
Source:	Fujitsu
Title:	Modulation for R2D
Document for:	Discussion

Conclusion
In this contribution, we have the following proposals and observations:
Proposal 1: For the CP handling at device side, support Option 3 for the case with M values >12.
Proposal 2: The R2D chip duration is 1/M of one OFDM symbol without CP.
Proposal 3: Regarding to the padding for R2D transmissions, prefer Alt 1b.
Proposal 4: 
Prefer an explicit indication from readers to devices to assist the determination of the position of the end of PRDCH at the device side.
In addition, as a double check to the position of the end of PRDCH, a post-amble may be loosely defined, or the padding part if any is assumed to not follow the rules of the Manchester code.

3GPP TSG RAN WG1 #121		R1-2504098 
St.Julians, Malta, May 19th – 23rd, 2025

Source:	HONOR
Title:	Discussion on Physical channels design for Ambient IoT– modulation aspects
Agenda Item:	9.4.1
Document for:	Discussion and Decision

Conclusions
In this contribution, we provide our views on Physical channels design for Ambient IoT system. The following observations and proposals are given:
Proposal 1: CAP in R-TAS uses the same M values set as PRDCH.
Proposal 2: For CP handling, only support Method Type 1 in which removal of CP at device side.
Proposal 3: For R2D chip duration, the length of R2D chip duration (denoted as ‘C’) in one OFDM symbol is defined as: C = (1/SCS)/M
Proposal 4: For R2D padding, support Alt 1b in which the content of padding is up to reader implementation and the timeline determination refers to the start of the padding.

Observation 1: One CP handling solution means only one method could be selected for both small and large M values.
Observation 2: A-IoT devices can support Method Type 1 by implementing Alt M1-1 or Alt M1-2 depending on M value indicated by preamble without standard effort.
Observation 3: Supporting different CP handling design for different M values increases the complexity for device.

3GPP TSG RAN WG1 #121		R1-2504205
St Julian’s, Malta, May 19th – 23rd, 2025

Source:	OPPO
Title:	Discussion on modulation aspects of A-IoT
Agenda item:	9.4.1
Document for:	Discussion and Decision

Conclusion
In this contribution, we discuss the R2D transmission, including the M values, CP handling, padding for R2D transmission. Observations and proposals are summarized as following: 
Proposal 1: If M values used for PRDCH transmission is derived by CAP rather than R2D control information, support CAP use same M values set as PRDCH.
Proposal2: CP handling Method Type 1 is not applied to CAP detection.
Observation 1: The updated Candidate 3 in agreement is not aligned with definition of M2-1-1 (as per TR 38.769).
Observation 2: The BLER of PRDCH with option 3 can reach the target and thus no enhancement is needed.
Proposal3: For CP handing which retains subcarrier orthogonality, support Option 3: RAN1 will not further pursue additional CP handling design
Proposal4: For Padding in R2D transmission, Alt 1b should be supported. Furthermore, the padding should be distinctive from SIP.

3GPP TSG RAN WG1 #121				R1-2504243
Saint Julian’s, Malta, May 19th – 23rd, 2025

Agenda Item:	9.4.1
Source: 	LG Electronics
Title: 	A-IoT PHY layer design – waveform and modulation aspects
Document for:	Discussion and decision

Conclusion
	In this contribution, we shared our views on general aspects of Ambient IoT physical layer design.
Observation 1: Using Method Type 1 Alt 2 alone, Ambient IoT devices can handle the CP for M values up to 8.
Observation 2: Using Method Type 1 Alt 2 combined with Method Type 1 Alt 1, Ambient IoT devices can also handle the CP with large M values.
Proposal 1: Support Option 3 for supported M values > 12
Observation 3: Additional resource overhead is required for Option 1
Proposal 2: CAP should be designed to ensure reliable operation irrespective of the CP handling method
Proposal 3: Support Option 1 for R2D chip duration
Proposal 4: R2D chip duration is indicated in CAP of R-TAS.
Proposal 5: The chip durations for L1 R2D control (if supported) and R2D data are the same.
Proposal 6: Support Alt 2. The content of the padding can be specified to meet at least one of the following objectives
Facilitating additional synchronization
Indicating the end timing of PRDCH
Enhance postamble’s (if supported) reliability

3GPP TSG RAN WG1 #121	                                                                        R1-2504287
St Julian’s, Malta, May 19th – 23rd, 2025

Agenda Item:	9.4.1
Source: 	InterDigital, Inc.
Title:		Remaining issues on modulation aspects for Ambient IoT
Document for:	Discussion and Decision
1. 

Summary
This contribution has discussed remaining issues in modulation aspects of physical channel design for Ambient IoT. The following are proposed and observed.
Observation 1: For decoding in Candidate 3 of Method 2, device only needs to detect the edges and does not need to remove the CP samples.
Observation 2: Method 1 is prone to decoding errors because of false edges created by removing non-CP samples. 
Proposal 1: For CP handling when M > 12, support Option 1:
Option 1: Candidate 3 of M2-1-1 (as per agreements from RAN1#120): The last 2 out of M OOK chips at the end of an OFDM symbol are always ‘ON’
Proposal 2: When the generated number of chips for the R2D transmission does not fully occupy the last OFDM symbol, padding is used.
Alt 1b: The content of padding is up to reader implementation and transparent to device.
Note: the timeline determination of any timing relationship refers to the start of the padding.

3GPP TSG RAN WG1 #121		             R1-2504318
St Julian’s, Malta, May 19th – 23rd, 2025

Agenda Item:	9.4.1
Source:	Apple
Title:	On remaining modulation aspects for Ambient IoT
Document for:	Discussion/Decision

Conclusion
In this contribution, following observations/proposals have been made related to modulation aspects for ambient IoT:
Observation 1: Chip duration is correlated to CP handling method and for Method Type 1, chip duration is fixed and depends on symbol duration and corresponding value of M

Observation 2: Once the end of R2D is determined, there is no need for device to process R2D postamble (if supported), as it serves no functionality at device side


Proposal 1: For CP handling method, for M > 12, adopt option 3, i.e. RAN1 will not pursue additional CP handling method (in addition to already agreed Method Type 1)
With option 1, we think that this is not aligned with WID objective on CP handling method which states to adopt only one solution

Proposal 2: If Method Type 1 (including Alt M1-1 and/or Alt M1-2) is adopted, then chip duration :  

Proposal 3: Support variable length padding for aligning with boundary of the last OFDM symbol, after addition of R2D postamble (if supported):
For M = 2, PDRCH will always be aligned with end of last OFDM symbol and if postamble of 3 chips is added, then required R2D padding is only 1 chip long
For M = 6, the end of PRDCH, if misaligned with the boundary of last OFDM symbol, will be fixed and equal to 2 chips and if postamble of 3 chips is added, then R2D padding is 5 chips long, otherwise R2D padding is 3 chips long if there is no misalignment before R2D postamble
For M = 12, the end of PRDCH, if misaligned with the boundary of last OFDM symbol, will be fixed and equal to 8 chips and if postamble of 3 chips is added, then R2D padding is 5 chips long, otherwise R2D padding is 9 chips long if there is no misalignment before R2D postamble
For M = 24, the end of PRDCH, if misaligned with the boundary of last OFDM symbol, will be fixed and equal to 20 chips and if postamble of 3 chips is added, then R2D padding is 17 chips long, otherwise R2D padding is 21 chips long if there is no misalignment before R2D postamble

Proposal 4: Adopt end of R2D postamble (alternatively start of R2D padding) as the reference point for timeline determination for further transmission/reception at the device. 

3GPP TSG RAN WG1 #121								R1-2504394
St Julian’s, Malta, May 19th – 23th, 2025

Source: Qualcomm Incorporated
Title: Physical channels design – modulation aspects
Agenda Item:	9.4.1
Document for:	Discussion and Decision

Conclusion

Observation 1: For CP handling Method M1-1, poor clock accuracy affects the identification of CP location and removal of CP and degrade performance.
Observation 2: For CP handling Method M1-1, during CAP detection, device may need to adjust its internal clock or adjust internal clock tick threshold for the detected chip duration (i.e., M value) to make accurate removal of CP duration.
Observation 3: CP handling Method M1-1 can support up to M=24 in TDL-A fading channel.
Observation 4: M2-1-1 Candidate 3’s overhead due to the last two ON chips is 8.3%.
Observation 5: CP handling method M2-2 can support M=24 in TDL-A fading channel.
Observation 6: CP handling method M2-2 cannot support M=32 in TDL-A fading channel.
Observation 7: The benefit of orthogonal CP handling scheme is valid only when outdoor NR gNB is synchronized with indoor A-IoT gNB.
Observation 8: In FDD spectrum, gNB time synchronization is not strongly required.
Observation 9: If outdoor gNB and indoor gNB are not synchronized, then, even orthogonal CP handling scheme introduces ICI. Thus, there is no strong benefit of using orthogonal CP handling scheme in FDD spectrum.
Proposal 1: For CP handling scheme, RAN1 to prioritize CP handling methods of Alt M2-2 and Alt M1-1 for all M values.
Observation 10: Device can utilize falling edges of CAP for all M values of 2, 6, 12 to detect M value in CAP. Device does not require specific CP handling scheme for CAP for M=2,6, 12.

Observation 11: For CAP M=24, CP handling for CAP is could be done by padding bits in the end of OFDM symbol or just left as an implementation issue to device (i.e., device detects either two or three falling edges).

Proposal 2: For CAP M=24, down select CP handling scheme for CAP between 1) adding padding bits in the end of OFDM symbol, and 2) just left as an implementation issue to device (i.e., device detects either two or three falling edges).
Proposal 3:
For M1-1, R2D chip duration is determined as    (i.e. w/o considering CP duration).
For M2-2, R2D chip duration is determined as    (i.e. with considering CP duration).
In the above, SCS is subcarrier spacing in Hz and M is the number of chips per OFDM symbol.

Proposal 4: For potential padding at the end of R2D transmission, RAN1 supports Alt 1b.
Alt 1b: The content of padding is up to reader implementation and transparent to device.
Note: the timeline determination of any timing relationship refers to the start of the padding.

3GPP TSG RAN WG1 #121                                   R1-2504433
St Julian’s, Malta, May 19th - 23rd, 2025

Source:	Sharp
Title:	Discussion on modulation aspects
Agenda Item:	9.4.1
Document for:	Discussion and Decision

Conclusion
In this contribution, we discuss a few modulation aspects of the A-IoT physical layer channel design, and make the following observation and proposals.
In R2D reception, the device has to remove the padding chips in order to correctly locate the CRC bits and perform CRC checking, and for that purpose, the device has to differentiate padding chips from “normal” PRDCH chips (e.g. by means of violating Manchester coding rules in the padding chips), which cannot be ensured if RAN1 simply concludes that the content of padding is “up to reader implementation and transparent to device”.
For CP handling with M values > 12, down-select to Method Type 1.
Note 1: use of Alt M1-1 and/or Alt M1-2 is up to device implementation.
Note 2: no specification impact.
Same CP handling method is used for R-TAS and PRDCH.
R2D chip duration is defined as .
For R2D, the padding chips shall violate Manchester coding rules.
The detailed content of padding is up to reader implementation and transparent to the device.
For R2D, the timeline determination of any timing relationship refers to the end of padding.
For R2D, the transmitted signal should be within the resource grid, i.e. .

3GPP TSG RAN WG1 #121		R1-2504482

Malta, 19 May – 23 May 2025

Agenda item:	9.4.1
Source:		Indian Institute of Technology Madras [IITM]
Title:			Discussion on Modulation Aspects for Ambient IoT
Document for:	Discussion


1. 

TDoc file conclusion not found

3GPP TSG RAN WG1 #121							         R1-2504501
St Julian’s, Malta, May 19th – 23th, 2025

Source:	NTT DOCOMO, INC.
Title:	Discussion on modulation aspects of physical channel design for Ambient IoT
Agenda Item:	9.4.1
Document for: 	Discussion and Decision

Conclusion
In this contribution, we discussed modulation aspects on physical channel design for A-IoT device. Based on the discussion, we made following observations and proposals.
Observation 1: For R2D, candidate 3 of CP handling Method Type 2-1-1 introduces 8.3% overhead for parity chips when M=24.

Proposal 1: For PRDCH, support only CP handling Method Type 1 for M=24, i.e., support option 3 in the agreement at the RAN1#120bis.
Proposal 2: Confirm that start timing of R-SIP is aligned with the OFDM symbol boundary for CP handling of PRDCH reception.
R-SIP can start from any OFDM symbol.
Proposal 3: For PRDCH, one chip duration should be (1/SCS)/M.
Proposal 4: When the generated number of chips for the R2D transmission does not fully occupy the last OFDM symbol, padding is used while the content of padding it up to reader implementation and transparent to device.
The timeline determination of any timing relationship refers to the start of the padding.

3GPP TSG RAN WG1 #121                          		   R1-2504585
St Julian’s, Malta, May 19th – 23th, 2025

Agenda Item:	9.4.1
Source: 	China Unicom
Title: 	Discussion on physical channels design for A-IoT
Document for: 	Discussion and Decision
1. 

Conclusion
According to the discussion, following proposals are provided:
Proposal 1: Dynamically adjust R2D chip duration for chips adjacent to a CP.
Proposal 2: Implement a hybrid CP handling method for R2D transmission.
Proposal 3: Define core steps for DFT-s-OFDM waveform generation while allowing implementation flexibility.

3GPP TSG RAN WG1 Meeting#121	                            R1-2504617
Saint Julian, Malta, May 19th – 23rd, 2025

Source:	WILUS Inc.
Title:	Discussion on modulation aspects of physical channels design for Ambient IoT
Agenda item:	9.4.1
Document for:	Discussion/Decision

Conclusion
In this contribution, we discussed CP handling, padding for Ambient IoT and summarize our views as the following:
Proposal 1: Support CP handling Option 1 for M > 12, particularly when M=24, to minimize performance degradation due to discontinuities in the CP region
Proposal 2: Support Alt 2 for the preferred padding method for the last OFDM symbol
Use explicitly defined padding with all-zeros in chip level.

3GPP TSG RAN WG1 #121	 R1-2504633
St Julian’s, Malta, May 19th – May 23rd, 2025

Agenda item:       9.4.1
Source:                   IIT Kanpur
Title:                         Discussion on modulation aspects of physical channel design for AIoT
Document for:    Discussion and Decision

Conclusion
This paper provides the following observations and proposals:
Proposal 1: For R2D, support the use of the same M value set for CAP as is defined for PRDCH.
Proposal 2: For CP handling when M values >12, we prefer to support Option 1, which is candidate 3 of M2-1-1, where the last two chips are padded with an “ON” signal
Proposal 3: At least for the R2D transmissions, the time domain resource should be indicated in terms of OFDM symbols.
Proposal 4: Both Alt 1a and Alt 2 are fine for the R2D padding.   
Proposal 5: Since the CP is to be discarded by the device, we propose that the R2D chip duration be defined as C = (1 / SCS) / M.
4. 

3GPP TSG RAN-WG1 Meeting #121			R1-2504710
St Julian’s, Malta, 19-23 May, 2025

Source: 	Moderator (Huawei)
Title:	FL summary #1 for Ambient IoT: “9.4.1 Physical channels design – modulation aspects”
Document for:	Discussion and decision
Agenda item:	9.4.1

Conclusion
For CW waveform, A-IoT WID RP-243326 and TR 38.769 already give us:
It is left up to specification drafting phase how to capture the following.


Agreement
For R2D, for the OOK-4 modulation for M-chip per OFDM symbol transmission:
The maximum M value is no less than 16, and to be down-selected from 32, 24 or 16 at RAN1#120bis.

Agreement
For CP handling which retains subcarrier orthogonality, the candidate methods are clarified as follows:
For Method Type 1 (as per TR 38.769)
For purposes of evaluating Method Type 1, it is assumed the device is aware of or determines the boundary of an OFDM symbol using the R2D timing acquisition signal (R-TAS), at least for Alt M1-1
Detail is up to R2D preamble design
Using Alt M1-1 and/or Alt M1-2 is up to device implementation as per TR 38.769
FFS: applicable M values
For Method Type 2 Alt M2-1 (as per TR 38.769)
Detail design of Alt M2-1-1 or Alt M2-1-2 from the followings:
Alt M2-1-1
Candidate 1: 
For M less than 6: Use Alt M1-1
For M >=6: circular shift of the M chips’ samples before CP insertion at the reader side in addition to bit/chip skipping/dropping at the device side after bit decoding
Candidate 2:
Where a known signal shape in the tail-portion of the R2D signal is copied to the CP.
Candidate 3:
Insert padding chips at both start and end OOK chips or only at end OOK chips
Alt M2-1-2
Candidate 4:
Change  case to  case by changing OOK-4 M value to adjacent M +/- 1 for OFDM symbol n.
where a, b and c is the last chip of symbol n, first chip of symbol n+1 and last chip of symbol n+1.
Candidate 5:
Odd number of chips of PRDCH is transmitted in the first OFDM symbols, while M value is kept unchanged during the remaining OFDM symbols.
FFS: applicable M values with or without combination of Method Type 1

For CP handling which does not retain subcarrier orthogonality, the candidate methods are clarified as follows:
For Method Type 2 Alt M2-2 (as per TR 38.769)
FFS detail design of Alt M2-2 from the following:
Candidate 1:
A duration of OFDM symbol with CP has integer number of OOK symbols. CP is not copied from the end of OFDM symbol. Total 14 OFDM symbols fit in a slot.

For further down-selection among candidate methods which retains subcarrier orthogonality, companies are encouraged to provide evaluation (including overhead) among the followings to RAN1#120bis:
Method Type 1
Method Type 2 Alt M2-1-1 with or without combination of Method Type 1
Method Type 2 Alt M2-1-2 with or without combination of Method Type 1
Note: The evaluation for CP handling at least includes a M value from {2,4,6,8}, a M value from {12, 16}, and a M value from {24, 32}
Note: In this evaluation, the transmit power of the ON chips remains constant

Agreement
For D2R BPSK modulation
After line coding or square wave, chip “1” is mapped to the real-valued modulation symbol {1} and chip “0” is mapped to the real-valued modulation symbol {-1} in the baseband.

Agreement
For D2R OOK modulation
After line coding or square wave, chip “1” is mapped to the real-valued modulation symbol {1} and chip “0” is mapped to the real-valued modulation symbol {0} in baseband.

Agreement
For R2D transmission, from reader perspective, DFT-s-OFDM waveform is supported for OOK-4 modulation. For the details of DFT-s-OFDM waveform generation of OOK-4 modulation:
Certain specification of DFT-s-OFDM waveform generation for OOK-4 modulation is needed in RAN1.
FFS: identify what potential details of 5 steps in section 4.4 of TR 38.769 needs to be specified.
This does not preclude RAN4 to discuss R2D waveform generation themselves when defining requirement(s), if needed.

RAN1#120bis (Wuhan)

Agreement
For R2D, for the OOK-4 modulation for M-chip per OFDM symbol transmission, the maximum M value is 24.
RAN1 will further determine the set of M values up to the maximum M value.
The maximum M value applicable to the PRDCH is 24
The maximum M value applicable to the R-TAS is not larger than 24


Agreement
For R2D, at least for PRDCH, the set of M values is {2, 6, 12, 24}
FFS: whether/how CAP use same M values set as PRDCH

Agreement
For further down-selection among CP handing which retains subcarrier orthogonality, at least for PRDCH, at least Method Type 1 is supported
For supported M values <= 12
RAN1 will not further pursue additional CP handling design
For supported M values > 12
RAN1 will further down-select one from the followings
Option 1: Candidate 3 of M2-1-1 (as per agreements from RAN1#120)
Insert padding chips only at the end OOK chips of OFDM symbol
Option 3: RAN1 will not further pursue additional CP handling design

Agreement
Proposal: For Ambient IoT, RAN1 clarify that the definition of PRB is same as NR in TS 38.211.

Agreement
For the below agreement, further update on the followings
Agreement
For further down-selection among CP handing which retains subcarrier orthogonality, at least for PRDCH, at least Method Type 1 is supported
For supported M values <= 12
RAN1 will not further pursue additional CP handling design
For supported M values > 12
RAN1 will further down-select one from the followings
Option 1: Candidate 3 of M2-1-1 (as per agreements from RAN1#120)
Insert padding chips only at the end OOK chips of OFDM symbol
The last 2 out of M OOK chips at the end of an OFDM symbol are always ‘ON’
Option 3: RAN1 will not further pursue additional CP handling design

Agreement
When the generated number of chips for the R2D transmission does not fully occupy the last OFDM symbol, padding is used.
Padding is to be down-selected among the following alternatives:
Alt 1a: The content of padding is up to reader implementation and transparent to device.
Note: the timeline determination of any timing relationship refers to the end of padding.
Note: it implies the device should be aware of the duration of padding or the last OFDM symbol boundary by implementation. FFS how accurately the device can be aware.
Alt 1b: The content of padding is up to reader implementation and transparent to device.
Note: the timeline determination of any timing relationship refers to the start of the padding.
Alt 2: Specify the detailed content of padding
Note: the timeline determination of any timing relationship refers to the end of padding.
Note: the end chip(s) of the padding content shall follow the CP handling solution determined in RAN1, and may be affected by other agreements.

Agreement
From reader perspective, for the needed certain specification of DFT-s-OFDM waveform generation for OOK-4 modulation:
An example is provided below, which does not presume any specific reader implementation:
Step 1: The time domain OOK signal is the M chips of one OFDM symbol
The specification only needs to reflect that one OFDM symbol contains M chips
Step 2: A chip is represented (e.g. upsampled) by L samples
The specification only needs to reflect that one chip contains L samples as the input to N’-points DFT
Step 3: An N’-points DFT is performed on the samples of one OFDM symbol to obtain the frequency domain signal.
The specification only needs to reflect that there is an N’-points DFT operation, where N’ = M*L
Step 4: Map the frequency domain signal obtained by N’-points DFT to the X subcarriers of Btx,R2D
The specification only needs to reflect that N’ >= X, where X is corresponding to the Btx,R2D
Step 5: An N-points IDFT is performed to obtain the time domain signal.
The specification only needs to reflect that there is an N-points IDFT operation
Note: other examples were provided in contributions to RAN1#120bis, e.g. in annex 2 of R1-2502160
From the example above, some normative specification related to at least step 1 and step 5 are needed.
Note: RAN1 to consider whether an information annex could describe other steps
Note: some normative RAN1 specification text about waveform is assumed to be needed for RAN4 requirements definition
Note: the specification also needs to reflect the timing of the CP insertion operation.

3GPP TSG RAN-WG1 Meeting #121			R1-2504711
St Julian’s, Malta, 19-23 May, 2025

Source: 	Moderator (Huawei)
Title:	FL summary #2 for Ambient IoT: “9.4.1 Physical channels design – modulation aspects”
Document for:	Discussion and decision
Agenda item:	9.4.1

Conclusion
For CW waveform, A-IoT WID RP-243326 and TR 38.769 already give us:
It is left up to specification drafting phase how to capture the following.


Agreement
For R2D, for the OOK-4 modulation for M-chip per OFDM symbol transmission:
The maximum M value is no less than 16, and to be down-selected from 32, 24 or 16 at RAN1#120bis.

Agreement
For CP handling which retains subcarrier orthogonality, the candidate methods are clarified as follows:
For Method Type 1 (as per TR 38.769)
For purposes of evaluating Method Type 1, it is assumed the device is aware of or determines the boundary of an OFDM symbol using the R2D timing acquisition signal (R-TAS), at least for Alt M1-1
Detail is up to R2D preamble design
Using Alt M1-1 and/or Alt M1-2 is up to device implementation as per TR 38.769
FFS: applicable M values
For Method Type 2 Alt M2-1 (as per TR 38.769)
Detail design of Alt M2-1-1 or Alt M2-1-2 from the followings:
Alt M2-1-1
Candidate 1: 
For M less than 6: Use Alt M1-1
For M >=6: circular shift of the M chips’ samples before CP insertion at the reader side in addition to bit/chip skipping/dropping at the device side after bit decoding
Candidate 2:
Where a known signal shape in the tail-portion of the R2D signal is copied to the CP.
Candidate 3:
Insert padding chips at both start and end OOK chips or only at end OOK chips
Alt M2-1-2
Candidate 4:
Change  case to  case by changing OOK-4 M value to adjacent M +/- 1 for OFDM symbol n.
where a, b and c is the last chip of symbol n, first chip of symbol n+1 and last chip of symbol n+1.
Candidate 5:
Odd number of chips of PRDCH is transmitted in the first OFDM symbols, while M value is kept unchanged during the remaining OFDM symbols.
FFS: applicable M values with or without combination of Method Type 1

For CP handling which does not retain subcarrier orthogonality, the candidate methods are clarified as follows:
For Method Type 2 Alt M2-2 (as per TR 38.769)
FFS detail design of Alt M2-2 from the following:
Candidate 1:
A duration of OFDM symbol with CP has integer number of OOK symbols. CP is not copied from the end of OFDM symbol. Total 14 OFDM symbols fit in a slot.

For further down-selection among candidate methods which retains subcarrier orthogonality, companies are encouraged to provide evaluation (including overhead) among the followings to RAN1#120bis:
Method Type 1
Method Type 2 Alt M2-1-1 with or without combination of Method Type 1
Method Type 2 Alt M2-1-2 with or without combination of Method Type 1
Note: The evaluation for CP handling at least includes a M value from {2,4,6,8}, a M value from {12, 16}, and a M value from {24, 32}
Note: In this evaluation, the transmit power of the ON chips remains constant

Agreement
For D2R BPSK modulation
After line coding or square wave, chip “1” is mapped to the real-valued modulation symbol {1} and chip “0” is mapped to the real-valued modulation symbol {-1} in the baseband.

Agreement
For D2R OOK modulation
After line coding or square wave, chip “1” is mapped to the real-valued modulation symbol {1} and chip “0” is mapped to the real-valued modulation symbol {0} in baseband.

Agreement
For R2D transmission, from reader perspective, DFT-s-OFDM waveform is supported for OOK-4 modulation. For the details of DFT-s-OFDM waveform generation of OOK-4 modulation:
Certain specification of DFT-s-OFDM waveform generation for OOK-4 modulation is needed in RAN1.
FFS: identify what potential details of 5 steps in section 4.4 of TR 38.769 needs to be specified.
This does not preclude RAN4 to discuss R2D waveform generation themselves when defining requirement(s), if needed.

RAN1#120bis (Wuhan)

Agreement
For R2D, for the OOK-4 modulation for M-chip per OFDM symbol transmission, the maximum M value is 24.
RAN1 will further determine the set of M values up to the maximum M value.
The maximum M value applicable to the PRDCH is 24
The maximum M value applicable to the R-TAS is not larger than 24


Agreement
For R2D, at least for PRDCH, the set of M values is {2, 6, 12, 24}
FFS: whether/how CAP use same M values set as PRDCH

Agreement
For further down-selection among CP handing which retains subcarrier orthogonality, at least for PRDCH, at least Method Type 1 is supported
For supported M values <= 12
RAN1 will not further pursue additional CP handling design
For supported M values > 12
RAN1 will further down-select one from the followings
Option 1: Candidate 3 of M2-1-1 (as per agreements from RAN1#120)
Insert padding chips only at the end OOK chips of OFDM symbol
Option 3: RAN1 will not further pursue additional CP handling design

Agreement
Proposal: For Ambient IoT, RAN1 clarify that the definition of PRB is same as NR in TS 38.211.

Agreement
For the below agreement, further update on the followings
Agreement
For further down-selection among CP handing which retains subcarrier orthogonality, at least for PRDCH, at least Method Type 1 is supported
For supported M values <= 12
RAN1 will not further pursue additional CP handling design
For supported M values > 12
RAN1 will further down-select one from the followings
Option 1: Candidate 3 of M2-1-1 (as per agreements from RAN1#120)
Insert padding chips only at the end OOK chips of OFDM symbol
The last 2 out of M OOK chips at the end of an OFDM symbol are always ‘ON’
Option 3: RAN1 will not further pursue additional CP handling design

Agreement
When the generated number of chips for the R2D transmission does not fully occupy the last OFDM symbol, padding is used.
Padding is to be down-selected among the following alternatives:
Alt 1a: The content of padding is up to reader implementation and transparent to device.
Note: the timeline determination of any timing relationship refers to the end of padding.
Note: it implies the device should be aware of the duration of padding or the last OFDM symbol boundary by implementation. FFS how accurately the device can be aware.
Alt 1b: The content of padding is up to reader implementation and transparent to device.
Note: the timeline determination of any timing relationship refers to the start of the padding.
Alt 2: Specify the detailed content of padding
Note: the timeline determination of any timing relationship refers to the end of padding.
Note: the end chip(s) of the padding content shall follow the CP handling solution determined in RAN1, and may be affected by other agreements.

Agreement
From reader perspective, for the needed certain specification of DFT-s-OFDM waveform generation for OOK-4 modulation:
An example is provided below, which does not presume any specific reader implementation:
Step 1: The time domain OOK signal is the M chips of one OFDM symbol
The specification only needs to reflect that one OFDM symbol contains M chips
Step 2: A chip is represented (e.g. upsampled) by L samples
The specification only needs to reflect that one chip contains L samples as the input to N’-points DFT
Step 3: An N’-points DFT is performed on the samples of one OFDM symbol to obtain the frequency domain signal.
The specification only needs to reflect that there is an N’-points DFT operation, where N’ = M*L
Step 4: Map the frequency domain signal obtained by N’-points DFT to the X subcarriers of Btx,R2D
The specification only needs to reflect that N’ >= X, where X is corresponding to the Btx,R2D
Step 5: An N-points IDFT is performed to obtain the time domain signal.
The specification only needs to reflect that there is an N-points IDFT operation
Note: other examples were provided in contributions to RAN1#120bis, e.g. in annex 2 of R1-2502160
From the example above, some normative specification related to at least step 1 and step 5 are needed.
Note: RAN1 to consider whether an information annex could describe other steps
Note: some normative RAN1 specification text about waveform is assumed to be needed for RAN4 requirements definition
Note: the specification also needs to reflect the timing of the CP insertion operation.

3GPP TSG RAN-WG1 Meeting #121			R1-2504712
St Julian’s, Malta, 19-23 May, 2025

Source: 	Moderator (Huawei)
Title:	FL summary #3 for Ambient IoT: “9.4.1 Physical channels design – modulation aspects”
Document for:	Discussion and decision
Agenda item:	9.4.1

Conclusion
The other steps (in addition to agreed Step 1 and Step 5) for R2D waveform generation will not be described in the RAN1 TS.

3GPP TSG RAN WG1 #121		             R1-2504714
St Julian’s, Malta, May 19th – 23rd, 2025

Agenda Item:	9.4.1
Source:	Apple
Title:	On remaining modulation aspects for Ambient IoT
Document for:	Discussion/Decision

Conclusion
In this contribution, following observations/proposals have been made related to modulation aspects for ambient IoT:
Observation 1: Chip duration is correlated to CP handling method and for Method Type 1, chip duration is fixed and depends on symbol duration and corresponding value of M

Observation 2: Once the end of R2D is determined, there is no need for device to process R2D postamble (if supported), as it serves no functionality at device side


Proposal 1: For CP handling method, for M > 12, adopt option 3, i.e. RAN1 will not pursue additional CP handling method (in addition to already agreed Method Type 1)
With option 1, we think that this is not aligned with WID objective on CP handling method which states to adopt only one solution

Proposal 2: If Method Type 1 (including Alt M1-1 and/or Alt M1-2) is adopted, then chip duration :  

Proposal 3: Support variable length padding for aligning with boundary of the last OFDM symbol, after addition of R2D postamble (if supported)considering maximum R2D padding values as below for different M values:

Proposal 4: Adopt end of R2D postamble (alternatively start of R2D padding) as the reference point for timeline determination for further transmission/reception at the device