3GPP TSG RAN WG1 Meeting #120bis	R1-2501707
Wuhan, China, April 7 – 11, 2025
Agenda Item:	9.4.2
Source:	Futurewei
Title:	Discussion on coding aspects for A-IoT physical channel
Document for:	Discussion and Decision 

Conclusion
The following observations and proposals were discussed in this contribution.
FEC
Observation 1: For the initialization of the CC encoder, CC encoding cannot start until the CRC parity sequence is available with option 1.
Observation 2: For the initialization of the CC encoder, CC encoding can occur at the same time as CRC encoding with option 2.
Observation 3: Option 2 allows implementations to reduce energy usage for CRC encoding and CC encoding or to reduce processing time.
Observation 4: Precomputed CRCs may not be possible for certain commands or use cases.
Observation 5: The same decoder for option 1 can be used with option 2. 
Proposal 1: For the initial values of the shift register of the CC encoder, 
The initial values of the shift register of the CC encoder are set to the values corresponding to the first (K-1) information bits, and the first (K-1) bits are appended to the end such that the initial state and ending state of the shift register are the same.
Note: K is the constraint length
CRC
Observation 6: The block error rate performance for a 6-bit CRC is at least 0.6 dB better than a 16-bit CRC for TBS between 24 and 56 bits simply because of less overhead for the weaker CRC code.
Observation 7: For the same BLER and a TBS range of 24 to 56 bits, the false alarm rate performance for a 6-bit CRC is about 2-3 times better than a 16-bit CRC simply due to the smaller CRC code.
Observation 8: For the same BLER and a TBS range of 24 to 56 bits, the undetected error performance of CRC-16 is at least 1000 times better than CRC-6.
Observation 9: In the TBS range of 24 to 56 bits, the undetected error performance of CRC-6 is flat. 
Observation 10: For a TBS in the range of 24 to 56 bits, it would be a very poor system design to use CRC-16 for a message type if the error detection performance of CRC-6 is sufficient. It would also be a very poor system design to use CRC-6 for a message type that could not tolerate 1000x worse error detection. 
Proposal 2: Consider further the message types and sizes before selecting the breakpoint between CRC-6 and CRC-16.
Proposal 3: The following option is supported to determine when no CRC is used:
Option 2: Specified condition(s), e.g., device transmits PDRCH for Msg 1 upon receiving a PRDCH triggering random access. FFS specified condition(s) and/or how to determine the specified condition(s).

Observation 11: Each segment of a segmented packet should use CRC-16.
Proposal 4: A device will use CRC-16 for a “last segment” following a “non-last segment” per the 1-bit indication introduced by RAN2.
Coding rate
Observation 12: For D2R transmissions, coding rate of 1 is achieved when no FEC is applied and when the number of block repetitions Rblock is 1
Proposal 5: Support a rate-1/2 FEC code rate that is produced by not transmitting the CC output corresponding to the polynomial G2(D) = 1+D+D2+D4+D6.
Proposal 6: For the D2R link, support a table of overall coding rates and the corresponding convolutional coding rate and number of repetitions.
Coding rates include at least 1, 1/3, 

3GPP TSG-RAN WG1 Meeting #120bis	R1- 2501720
Wuhan, China, April 7th – April 11th, 2025

Agenda Item:	9.4.2
Source:	Ericsson
Title:	Coding aspects for Ambient IoT
Document for:	Discussion, Decision
1	

Conclusion
In the previous sections we made the following observations:
Observation 1	OOK modulation without Manchester encoding has several drawbacks, such as synchronization issues, threshold sensitivity, and susceptibility to noise.
Observation 2	The optimal length of the CRC should be determined by factors such as message size, target false alarm rate (associated with the message type), and complexity.
Observation 3	R2D trigger messages, such as Msg0 and QueryRep-like messages (if applicable), might not require CRC. Otherwise, if the device does not know the size of Msg0 beforehand, blind decoding with different CRC lengths would be necessary.
Observation 4	The maximum value of Y is dependent not only based on the Rmax value, but also on the gap between two adjacent R values corresponding to any two devices on the adjacent FDMA occasions.

Based on the discussion in the previous sections we propose the following:
Proposal 1	Support Manchester line code as specified in TR 38.769 for both R2D and D2R with OOK modulation.
Proposal 2	The initial values of the shift register of the CC encoder are set to the values corresponding to the last (K-1) information bits defined in TS 36.212.
Proposal 3	Support FEC with a coding rate of 1/2, which can be achieved through puncturing, instead of using simple repetition.
Proposal 4	The selection threshold between CRC-6 and CRC-16, denoted as X, can be down-selected to X = 24
Proposal 5	No CRC can be used at least for Msg1 and R2D trigger messages like Msg0, QueryRep-like messages (if they exist).
Proposal 6	RAN1 to determine which of the following options to support:
Tb is the same for all the FDMA’ed devices in the same time occasion.
Tb can be different for the FDMA’ed devices in the same time occasion.
Proposal 7	RAN1 to determine which of the following options to support:
Bocc = Btx + Bguard is constant for all FDMA’ed devices in the same time occasion.
Bocc = Btx + Bguard can be different for the FDMA’ed devices in the same time occasion.
Proposal 8	Based on the supported options for Tb and Bocc, RAN1 to determine the minimum gap between two adjacent R values to avoid overlap between devices on the adjacent FDMA occasions.
Proposal 9	To determine Rmax value, RAN1 to clarify assumptions on maximum feasible clock frequency for the clock that enables small frequency shift as well as the minimum Tb (or equivalently the maximum data rate) that needs to be supported.
Proposal 10	The maximum value of Y is determined after clarifying the assumptions on the minimum gap between two adjacent R values as well as the assumptions needed to determine Rmax.

3GPP TSG RAN WG1 #120b                                            R1-2501734                
Wuhan, China, April 7th – April 11st, 2025

Source:	TCL
Title:	Discussion on line coding/FEC/CRC/repetition aspects for Ambient IoT
Agenda Item:	9.4.2
Document for:	Discussion and Decision

Conclusion
In this contribution, we provide our views on R2D and D2R coding/FEC/repetition related topics for AIoT. The observations and proposals are listed as below:
Observation 1: Regardless of the length of R2D data part, if the length of R2D control part greater than 16bit, CRC should be attached for control and data part respectively.
Observation 2: Whatever reader allocation or device generation for RN 16, whether attaching CRC for RN 16 is up to RN 16 belongs to D2R control message or data message, which should be decided by RAN 2.
Observation 3: If D2R Midamble used for PDRCH segmentation and used for SFO/channel/interference at reader side, CRC attachment is no need case limited PDRCH size and reliability may be achieved by D2R Midamble.
Observation 4: If no Device ID/EPC/Sensing data transmitted in D2R signal, or only RN 16 transmission, there is also no need to attach CRC in some certain
Observation 5: When PDRCH is segmented by D2R Midamble, CRC attachment is up to the length of segmented PDRCH. 
Observation 6: The candidate SFS set is obviously associated with repetition factor of Miller code, maximum D2R transmission BW and SCS.

Observation 7: Harmonic components (e.g., 3rd harmonic component) could impact the SFS configuration. Also, guard band between adjacent D2R signal could avoid the impact of SFO. 

Observation 8: It can be observation from RAN 1 #118b that there are different Btx,D2R and transmission power of the D2R transmissions due to XOR operation.

Observation 9: As the impact of SFO of device 1, each repetition block needs to consider the potential time offset (△t) to avoid the impact of SFO, which is up to the device’s capability and each block length. 

Observation 10: Limited by one bit length, the impact of SFO during one or multiple bit may be ignored, which is up to repetition number of bit-level repetition. 

Observation 11：For the number of bit-level repetition, it is up to coverage and access performance and it will impact on D2R frame structure selection.

Observation 12: For D2R transmission of AIoT, MCS-like is associated with D2R modulation (e.g., OOK and BPSK), channel coding (e.g., convolutional code), line code (e.g., with or w/o line code, repetition factor) or block/bit/chip-level repetition (e.g., repetition number).

Observation 13: D2R resource related Msg 1/3 repetition number/BLF could be saved if coverage is better. 

Observation 14: Reader sends one AIoT paging to devices that wait for inventory, and after a while, send again subsequent AIoT paging to inventory remaining device based on access successful rate. Subsequent AIoT paging could include more access resource or indication information if access successful rate is low. 


Proposal 1: Whether CRC is attached for R2D control part, it is up to the length of R2D control part.  
Proposal 2: Support 24 bit to be as one threshold for choosing CRC-6 or CRC-16 attachment.
Proposal 3: Support 16 bit to be as one threshold for considering whether CRC could be attached. 
Proposal 4: Assuming that there is no segmentation operation for D2R message, whether CRC is attached for D2R control part, it is up to the length of D2R control part. 
Proposal 5: Support no CRC attachment in some special cases, at least including
Re-transmission indication message(s) from reader to device, if any
Limited PDRCH size after segmentation, e.g., PDRCH size less than 16bit
The case that no Device ID/EPC/Sensing data transmitted in D2R signal
Only transmission RN 16 in D2R signal

Proposal 6：Discussion on how to indicate CRC attachment and length at least including
 Explicit indication by R2D control information
 Implicit indication

Proposal 7: Support 15KHz SCS as baseline to consider SFS configuration and meeting condition following
Maximum D2R transmission BW, e.g., 180KHz
Maximum repetition factor of Miller coding
Considering guard band between adjacent D2R signal to avoid the impact of SFO
Harmonic components at least including 3rd harmonic component

Proposal 8: Support option 1 or no D2R line code (e.g., by using a square-wave corresponding to the small frequency-shift)

Proposal 9: Consider the impact of M value and RB allocation on repetition factor of D2R Manchester line code 

Proposal 10: Consider D2R block-level repetition based on following aspects,
Frequency resource for each repetition block, e.g., if hopping frequency could be considered for each block
Repetition number (R)
How to indicate frequency resource and repetition number (R)

Proposal 11: Consider D2R bit-level repetition based on following aspects,
Repetition number (R)
How to indicate time/frequency resource and repetition number (R)
Proposal 12: Consider the follow equation as baseline to further study guard band of D2R signal:
⑦=(②-1/(chip durationfrequency-shif factor))/2±BWSFOmax, where BWSFOmax represents the occupied BW due to SFO


1）Btx, D2R; 2）Bocc, D2R; 3) Btx, CW;  4）Bocc, CW; 3)Gap between two single-tone; 6)Guard BW for CW;  7)Guard BW for D2R signal; 8）BAIoT, system; 9）Guard BW between AIoT and coexistence system
Proposal 13: Discuss the definition of MCS-like for D2R transmission after SFS discussion of 942.
Proposal 14: For the design of random ID, clarify that in which group (RAN1 or RAN2) should it be discussed.

3GPP TSG RAN WG1 meeting #120bis                                R1- 2501761
Wuhan, China, April 7th – 11th, 2025

Source: 	ZTE Corporation, Sanechips
Title:	Discussion on Ambient IoT coding
Agenda Item:	9.4.2
Document for:	Discussion and decision

Conclusion
In this contribution, we discuss the Ambient IoT coding design and have the following observations and proposals.
The R value set for different D2R transmission bandwidth/bit duration is nested, i.e., the R value sets of larger D2R transmission bandwidth (a.k.a smaller bit duration) are a sub-set of those of smaller D2R transmission bandwidth (a.k.a larger bit duration).
Assuming the indicated D2R chip duration corresponds to a predefined R value, the D2R chip duration corresponds to other R can be determined according to Tcj=Tci*Ri/Rj, wherein Tci (or Tcj) corresponds to the chip duration of Ri (or Rj).
Compared to Option 1, encoding delay advantage of Option 2 has no practical benefit and is negligible. 
Option 1 is very mature, and many products have been verified.  
Option 1 does not require additional memory or registers to buffer information bits or processing data. 
Option 1 allows for pipelined processing of Viterbi decoding and CRC checking. 
The decoding complexity for Option 2 may be somewhat higher than that of Option 1. 
In LTE convolutional coding of 1/3, the encoded bits are output in the following order: first, all bits from the 0th component code, followed by all bits from the 1st component code, and finally all bits from the 2nd component code.
In LTE convolutional coding, for the code rate of 1/2, all bits of the 0th component code and the 1st component code are output.  

The starting point of D2R chip durations can be {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 with potential down selection considering peak data rate, clock sampling frequency, and indication overhead.
The R set is suggested as {2, 8, 16, 32, 64, 128, 256} for small frequency shift.
Clarify that ‘Chip duration’ for D2R scheduling indicates D2R chip duration corresponds to the chip duration of a predefined R value, for example R=1,2, to reduce indication overhead.
For the indication of R values based on a predefined R set, Alt.3 is preferred to reduce the indication overhead.
It is proposed that the initial values of the shift register of the CC encoder are set to the values corresponding to the last (K-1) information bits defined in TS 36.212. 
Clarify that output bit sequence of convolutional coding is for code rate 1/3 and for code rate 1/2 , wherein bit  corresponds to the 0th component code with polynomial(133), bit  corresponds to the 1st component code with polynomial(171), and bit  corresponds to the 2nd component code with polynomial(165). 
The code rates and repetitions table is design to distribute the BLER curve as evenly as possible for each combination of code rate and repetitions. 
It is proposed that code rates and repetitions are jointly indicated with M bits, wherein M is equal to 2, or 3. 
In the Code rates and repetitions table indicated with 2 bits, including following the code rates and repetitions combinations: {1, 1}, {1/2, 1}, {1/3, 2}, {1/3, 6}. 
In the Code rates and repetitions table indicated with 3 bits, including following the code rates and repetitions combinations: {1, 1}, {1/2, 1}, {1/3, 1}, {1/3, 2}, {1/3, 4}, {1/3, 8}, {1/3, 16}, {1/3, 32}. 
It is proposed to support payload sizes range of 8 to 1000.  
It is proposed to support a payload size table indicated by S bits for R2D or/and D2R, wherein S is equal to 3, 4, or 5. 
If 3 bits indication is used, adopt following payload size table for R2D or/and D2R: 
If 4 bits indication is used, adopt following payload size table for R2D or/and D2R: 
If 5 bits indication is used, adopt following payload size table for R2D or/and D2R: 

3GPP TSG RAN WG1 #120b	R1-2501777
Wuhan, China, April 7th - 11th, 2025

Source:	Nokia
Title:	AIoT Physical channels design - line coding, FEC, CRC, repetition aspects
Agenda item:	9.4.2
Document for:	Discussion and Decision

Conclusion

In this contribution we have made the following observations and proposals:
Proposal 1: Regarding determination whether to use CRC, the details can be decided after RAN2 has made further progress on defining the messages and their sizes. 
Proposal 2: Regarding determination whether to use CRC for a D2R message, consider adopting the RFID mechanism of letting the reader indicate for specific D2R messages whether the device shall include CRC. 
Proposal 3: RAN1 supports CRC-16 in case message size is greater than X=24 bits (Alt. 1). Otherwise, CRC-6 or no CRC is used.
Proposal 4: In D2R control signaling, whether FEC is applied, which FEC code rate (if multiple code rates are supported) and the number of block level repetitions can be jointly encoded.

3GPP TSG RAN WG1 #120bis	R1-2501807
Wuhan, China, April 7th - 11st, 2025

Source:	vivo
Title:	Discussion on line coding, FEC, CRC and repetition for A-IoT  
Agenda Item:	9.4.2
Document for:	Discussion and Decision

Conclusion
In this contribution, we provide our views on remaining issues of physical channel design aspects including CRC attachment, FEC, repetition, and small frequency shift for A-IoT channels. The observations and proposals are summarized as follows.
Observation 1: Small frequency shift value lower than 15kHz suffers BLER error floor, in case of CW with 50dB CW interference power to signal power ratio with presence of phase noise of CW transmission from outside topology. 
The minimum small frequency shift value depends on the CW cancellation capability in D1T1-B and phase noise profile for CW node.

Proposal 1: RAN1 decides CRC length based on the number of information bits
No CRC for the number of information bits no larger than 8;
6-bit CRC for the number of information bits larger than 8 and no less than 24;
16-bit CRC for the number of information bits larger than 24. 
Proposal 2: Support TBCC, i.e., the initial values of the shift register of the CC encoder are set to the values corresponding to the last (K-1) information bits defined in TS 36.212.
Proposal 3: Support configurable presence of FEC. In case of enabled FEC, only support 1/3 code rate for FEC. 
Proposal 4: For an D2R transmission with block level repetition, 
Block-level repetition only applies to PDRCH.  
Single preamble preceding 1st repetition of PDRCH is transmitted and midambles (if any) are inserted within whole duration of PDRCH repetitions, where the number of midmables and locations of midambels are determined by the duration of all repetitions of PDRCH rather than each repetition of PDRCH.
PDRCHs and x-ambles in the D2R transmission is consecutive in time domain.
Proposal 5: Support block level repetition with repetition factor up to 4. 
Proposal 6: For D2R small frequency shift, 
Support small frequency shift values chosen from {30, 45, 60, 90, 120, 180, 240, 360, 480, 720} kHz 
Minimum value should be no smaller than 15kHz to avoid serious performance degradation caused by CW interference
Maximum value should be no smaller than 640kHz to achieve data rate no smaller than RFID. 
Candidate values support D2R chip duration a multiple division or multiplication of a R2D chip duration
Support codeword repetition number R chosen from {1,2,4,8,16,32,64,128} with potential down-selection up to Y, where Y=[4], 
Selection of R and Y should avoid interference from odd harmonics and provide sufficient gap among adjacent frequency resource occasions. 
Proposal 7: For R2D, support a set of chip duration {4.17, 8.34, 16.67, 33.35}us corresponding to M = {16, 8, 4, 2}. The chip duration is derived from the clock-acquisition part of R2D timing acquisition signal. 

3GPP TSG RAN WG1#120bis                                                                R1-2501869
Wuhan, China, April 7 – 11, 2025
Agenda Item:     9.4.2
Source:	Spreadtrum, UNISOC
Title:	Discussion on line coding, FEC, CRC, repetition aspects for Ambient IoT
Document for:	Discussion and decision

Conclusion
The following observations and proposals are achieved:
Observation:
Observation 1: In case of large SFO, the embedded clock information in Manchester line code is beneficial for reader to adjust timing for demodulation.
Observation 2: There are two interpretation regarding the case of R = 1 with no line coding:
Interpretation 1: no additional processing is applied for no line coding, which may lead to occurrences of consecutive zeros or consecutive ones.
Interpretation 2: the information bit can be assumed to be modulated by a BPSK square wave, which may require an additional square wave generator, adding the complexity of device implementation.
Observation 3: The number of 8 values for R is sufficient to meet the system capacity requirements.
Observation 4: For ZTCC, additional zero bits are appended to ensure that all the encoder's final state returns to zero, which leads to the overhead increasing. 
Observation 5: For truncation convolutional code, simply stopping after encoding completing the entire sequence of information bits will impact the decoding performance due to a tail effect.
Observation 6: Considering the forward design aspect, TBCC with Option 2 will lead to decoder complexity for intermedium UE as D2T2 will be introduced in R20.
Observation 7: The length of the bit sequence input to FEC should be larger than 6 to keep the initial value of the shift register set to the values corresponding to the last 6 information bits in the input stream.
Observation 8: The determination of the CRC length is related to the factor of TBS, Target false alarm rate, and whether repetition is performed during PRDCH/PDRCH generation.
Observation 9: For PDRCH repetition case, the ratio of useful signals is always less than 50%; when TBS is larger than to certain number, e.g. 48bit, the ratio of useful signals is insensitive to the length of CRC (6 or 16 CRC). 
Observation 10: It may cause redundant to discuss puncturing or other alternative schemes for a flexible code rate, which can be achieved simply by no FEC + repetition.

Proposal:
Proposal 1: Support using Manchester line code for D2R transmission.
Proposal 2: Support the maximum value of R up to 128 with the assumption of device sampling frequency 1.92 MHz and minimum Btx,D2R with 15kHz. 
Proposal 3: For D2R transmission with small frequency shift +/- R/Tb Hz, for the value R, supporting Alt.1, i.e., A subset of R = 2n, n = 0, 1, 2, 3, 4, 5, 6, 7.
Proposal 4: A D2R chip corresponds to one modulated symbol for OOK and BPSK. RAN1 further defines the D2R chip duration considering at least the following:
A D2R chip duration is a multiple division or multiplication of a R2D chip duration, to avoid introducing additional counting errors.
The minimum D2R chip duration should be 1.04 us, the peak data rate is 960 kHz if FEC code rate = 1 and includes at least 2 sampling points per chip.
The maximum D2R chip duration should be no smaller than 133.33 us.
Proposal 5: Further quantitative analysis is needed on how much proportion of CRC processing time can be saved compared with the whole processing time of the generation of PDRCH procedure.
Proposal 6: It needs further study that whether registers can be reused in two non-overlapped processing procedures, e.g., the timing counting and storing the CRC output.
Proposal 7: Support TBCC with Option 1 for D2R transmission.
Proposal 8: For small size data, e.g., bit size smaller than 6, no FEC in D2R.
Proposal 9: For PRDCH/PDRCH transmissions with CRC, the used CRC length depends on the number of bits Z before CRC, while Z=TBS*rep_num, i.e. No CRC for Z<=6, CRC-6 for 6< Z<=24 bits, and CRC-16 for Z > 24 bits. 
Proposal 10: One or both of the following options are supported to determine when no CRC is used,
Option 1: A threshold of number of information bits Y with 6bits. When the number of information bits is ≤ 6 bits, no CRC is used. 
Option 2: Specified condition(s), e.g., device transmits PDRCH for Msg1 upon receiving a PRDCH triggering random access, QueryRep-like messages in an inventory procedure.
Proposal 11: In the case of a conflict between these two conditions, Option 2 has a higher priority than Option 1, e.g., no CRC for Msg1 with RN16.
Proposal 12: Separate CRCs are supported for control and data segments in PRDCH.
Proposal 13: Support k =1 and k=3 to calculate the code rate of the convolutional encoder.
Proposal 14: Supporting the repetition number is {1，2}.
Proposal 15: The following bandwidth values should be considered for A-IoT D2R:
Transmission bandwidth, Btx,D2R is integer multiple(s) of 15k Hz
Occupied bandwidth, Bocc,D2R is integer multiple(s) of 180 kHz 
Bocc,D2R > Btx,D2R
Intra guard-band, Bguard,D2R can be 10% of transmission bandwidth Btx,D2R

3GPP TSG RAN WG1 #120bis                                                                                    		R1-2501993
Wuhan, China, April 7th – 11th, 2025
  
Source:             CATT
Title:                  Ambient IoT channel coding and small frequency shift 
Agenda Item:    9.4.2
Document for:  Discussion and Decision	

Conclusion
In this contribution, channel coding and small frequency shift technique for NR Ambient IoT communication system are discussed. We have the following observations and proposals:
Observation 1: With Manchester line coding, the R2D information data rate can be described as 1/(2*R2D chip length), and the R2D chip length is determined by the M value of OOK-4 and the OFDM symbol duration with 15k SCS .
Observation 2: Compared with TBCC, HBCC has no BLER performance gain, processing delay and memory size reduction, but it will cause the increase of processing complexity at device, decoding complexity at reader and additional complexity in the A-IoT circuit for parallel processing.
Proposal 1: Tail-biting convolutional code (TBCC) should be specified for Rel-19 D2R FEC code.
Proposal 2: For CC in A-IoT device 1
Repetition operation should be integral multiples of CC codeword.
Bit collection should be performed based on natural order of three encoder output parity streams.
Note: 
No need to support the sub-block interleaver(s) and puncturing operation of rate matching in LTE-TBCC.
Proposal 3: From the perspective of robustness of TBCC to SFO, D2R preamble design should ensure that residual timing error does not exceed 1000ppm.
Observation 3: With same coding rate, TBCC code has about 6dB coding gain than that of Manchester code at BLER=10%.
Observation 4: Compared with CC code only, CC concatenated with Manchester code would introduce unnecessary redundancy, while its performance is poor than that of convolutional code with repetition operation in case of SFO=1000ppm.
Proposal 4: Manchester line code should not be supported together with CC coding.
Proposal 5: If Manchester code is adopted for no FEC case, dynamic indication should be supported.
Observation 5: 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 6: 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. 
Observation 6: To generate D2R signal/channel with a small frequency shift, the device needs to know any two of the bit duration Tb, D2R chip duration and the number of square wave periods R.
Proposal 7: SFS factor R could be indicated in R2D control information.
Observation 7: From FDMA capacity perspective, the following is observed:
Compared to all alternatives of R values, SFS factor Alt.1() has the best FDMA capacity performance. 
The FDMA capacities of SFS factor Alt.2.1(R=2n) and SFS factor Alt.2.2 (removal of some values from  are comparable, and they are much larger than that of SFS factor Alt 3 (R=2n only).
Observation 8: Intra-channel interference due to frequency overlapping among D2R channels caused by small frequency shift using square wave modulation, could degrade BLER performance of D2R transmission significantly.
Observation 9: D2R transmissions with SFS factor R=2n have similar BLER performance without FDM performance degradation; however, the number of available D2R channels is reduced tremendously.  This will reduce the spectrum utilization.  
Observation 10: Compared to D2R channel(s) with SFS factor R, the BLER performance of D2R channels with SFS factor 3*R, 5*R and 7*R , due to odd harmonics interference, would be degraded by about 3dB, 1.5 dB and 0.8dB, respectively without interference cancellation at the reader. However, reader can perform interference mitigation with simple harmonics interference cancellation to ensure the BLER performance.
Observation 11: The BLER performance of D2R channels with 3rd harmonics interference cancellation is improved by 2dB compared with that of the D2R channel without harmonic interference cancellation.
Proposal 8: Considering very poor FDMA capacity performance of SFS factor Alt.3, R=2n only should not be supported for determination of the value of SFS factor in Rel-19 A-IoT.
Proposal 9: The following schemes should be supported for SFS factor value, 
SFS factor Alt.1:  
SFS factor Alt.2: 
SFS factor Alt.2.1: R=2n
SFS factor Alt.2.2: Removal of some values from , e.g., 
Proposal 10:  To improve frequency spectrum efficiency, D2R channel without small frequency shift should be supported for Msg1 transmission.
Proposal 11: The bandwidth of D2R channels for Msg1 from different devices corresponding to a R2D trigger should be the same.
Observation 12: The maximum value of Y for Msg1 FDMA transmissions is determined by the following factors
Bsystem: System bandwidth of D2R channels for Msg1 FDM;
BD2R: Transmission bandwidth for per device;
BD2R: Transmission bandwidth for per device;
SFO factor;
Guard band between NR and A-IoT.
Proposal 12: The maximum value of Y for Msg1 FDMA could be expressed as
Ymax= Rmax+1 for SFS factor Alt.1;
Ymax= floor(Rmax/2)+1 for SFS factor Alt.2.1;
Ymax= (floor(Rmax/2)-floor(Rmax/6))+1 for SFS factor Alt.2.2;
Ymax=floor(log2(Rmax))+1 for SFS factor Alt.3;
where  .
Proposal 13: The following tables should be used for determination maximum value of Y for Msg1 FDMA.
Maximum value of Y for Msg1 FDMA transmissions with 5MHz system bandwidth and SFO=105ppm

Maximum value of Y for Msg1 FDMA transmissions with 10MHz system bandwidth and SFO=105ppm

Proposal 14: Although SFS is equivalent to Manchester code bit level repetition in bit mapping perspective, but it cannot provide redundancy bits to obtain repetition coding gain. Manchester codeword repetition using for SFS purpose should not be supported as part of repetition coding scheme. 
Observation 13: For bit level repetition type 1, no repetition gain could be achieved as repetition bits are located within the same CC codeword and LLR combination cannot be performed.
Observation 14: Compared to block level repetition, bit level repetition type 2 would degrade both power efficiency and BLER performance in D2R transmission.
Proposal 15: Bit level repetition should not be supported for Rel-19 A-IoT.
Proposal 16: The following rule of CRC length determination should be adopted:
CRC-16 should be used for information bits length>X, otherwise CRC-6 is applied, where X= 24.
Proposal 17: RAN1 should clarify which A-IoT short message has very small payload size before supporting no CRC.
Proposal 18: When the number of information bits is ≤ 6, no CRC is used.
Proposal 19: Option 2: specified condition(s) of no use of CRC should not be supported.
Proposal 20:  Joint CRC should be applied to both R2D control information and R2D data.

3GPP TSG RAN WG1 #120bis			R1-2502023
Wuhan, China, April 7th – 11th, 2025

Agenda item:		9.4.2
Source:	China Telecom
Title:	Discussion on physical channels design about line coding, FEC, CRC, repetition aspects for Ambient IoT
Document for:		Discussion

Conclusion
In this contribution, we have the following proposals:
Proposal 1: A D2R chip corresponds to one modulated symbol for OOK and BPSK.
The D2R chip duration is Tb/(2 × R), where Tb is an D2R bit length and R is the small frequency shift factor.
A D2R chip duration is a multiple division or multiplication of a R2D chip duration, to avoid introducing additional counting errors.
Proposal 2: For D2R transmission with small frequency shift +/- R/Tb Hz,
The value of R = 1 and 2m, m = 1, 2, 3, 4…15
The value R can be indicated by reader via 4 bits (the subset number of R values is 16) or pre-defined rule of selecting R.
Proposal 3: Reuse the tail biting LTE convolutional code for D2R FEC (if applied).
The initial values of the shift register of the CC encoder are set to the values corresponding to the last (K-1) information bits defined in TS 36.212.
Proposal 4: Sub-block interleaving is not considered for Ambient IoT Device 1.
Proposal 5: For PRDCH/PDRCH transmissions with CRC attached, the used CRC length depends on the number of transmitted data bits X before CRC, i.e. CRC-6 for X<=24 bits, while CRC-16 for X >24 bits.
Proposal 6: For PRDCH/PDRCH transmissions with no CRC attached, a threshold of number of information bits Y is supported. When the number of information bits is ≤ Y bits, no CRC is used.
FFS: the value of Y.
Proposal 7: If bit-level repetition is considered for D2R transmission, bit-level type 2 can be supported.
Proposal 8: For block-level repetition, support the maximum number of repetitions can be no larger than 8.

3GPP TSG RAN WG1 #120bis	R1-2502069
Wuhan, China, April 7th – 11th, 2025

Agenda Item:	9.4.2
Source:	NEC
Title:	Physical layer design – line coding, FEC, CRC, repetition aspects
Document for:	Discussion and Decision
1	

Conclusion
In this contribution, we give our views on the aspects of line coding, FEC, CRC and repetition of ambient IoT physical channel design. We propose that:
Proposal 1: For the initial values of the shift register, Option 1 as defined in TS 36.212 is preferred.
Proposal 2: Alt. 2 with 56 bits is preferred as the upper limit for 6-bit CRC.
Proposal 3: Option 2 with specific condition(s) is supported for no CRC, with the specific conditions as Msg1 transmission or Msg2 transmission to multiple devices.
Proposal 4: The R value should fulfil the following conditions:
R value should be in formation of , with ;
Any value in the list of R should not be 3 or 5 multiples of another value in the list of R;
The gap between nearby R value should increase the value of R, due to SFO;
Proposal 5: The supported R list is {1, 4, 8, 15, 25, 36, 48, 64}.
Proposal 6: When applying small frequency shift, the density of ambles, at least midamble, is increased by small frequency shift factor R.
Proposal 7: When applying small frequency shift, the number of effective chips after small frequency shift should be multiples of R between nearby ambles.
Proposal 8: To avoid increase of amble overhead, the number of chips of each amble should be multiples of R.

3GPP TSG RAN WG1 #120bis		R1-2502124
Wuhan, China, April 7th – 11th, 2025
Agenda Item:	9.4.2
Source:	Fujitsu
Title:	Discussion on coding aspects
Document for:	Discussion

Conclusion
In this contribution, we discussed some issues relevant to FEC for D2R. We have the following proposals and observations:
Proposal 1: For the initial values of the shift registers of the CC encoder, adopt Option 1 for Device 1.
Proposal 2: Support puncturing scheme by using a puncturing matrix to achieve code rates higher than the mother code rate of the AIoT CC for D2R transmission.
Proposal 3: At least support the code rate of 1/2 for Device 1.
Proposal 4: When the information bits for once transmission on the D2R link are less than A bits, repetition scheme is preferred to protect these bits rather than CC.
The value of A is FFS.
Proposal 5: When the number of information bits is ≤ X bits, CRC-6 is used, X is 24.
Proposal 6: To determine when no CRC is used, support Option 1 only, i.e.,
A threshold of number of information bits Y. When the number of information bits is ≤ Y bits, no CRC is used.

Observation 1: The traditional puncturing scheme for CC can be considered for the AIoT CC for the following reasons. 
If puncturing matrix(es) is adopted for the AIoT CC to achieve a code rate higher that the code rate of the mother code,
No obvious delay is introduced in both the encoding procedure and the decoding procedure.
No obvious complexity increase is required in both the encoding procedure and the decoding procedure.
The puncturing method and the puncturing matrixes to a certain CC are traditional and long-standing for more than 30 years.
Assume to achieve the same code rate, puncturing is better than repetition, because puncturing can help to obtain both the channel coding gain and the energy accumulation gain, while repetition can only benefit from energy accumulation.
Observation 2: Repetition is not channel coding, which can provide zero channel coding gain.

3GPP TSG RAN WG1 #120-bis                             R1-2502161 
Wuhan, China, April 7th – 11th, 2025

Source: 	CMCC
Title:	Discussion on coding aspects of physical channel design
Agenda item:	9.4.2
Document for:	Discussion/Decision

Conclusions
In this contribution, we provide our views on coding aspects of physical channel design and the following observations and proposals are made:

Observation 1: Considering a minimum D2R transmission bandwidth of 15 kHz (which corresponds to the maximum D2R chip duration) is beneficial to meet coverage design target and to provide more FDMA capacity for D2R transmission.
Observation 2: The minimum D2R chip duration should ensure that the peak D2R data rate is larger than 640 kbps.
Observation 3: The minimum D2R chip duration should include at least 1 sample.
Observation 4: If device SFO = 0%, when R = 2n (n = 1, 2, …), the main lobes of different R are non-overlapped.
Observation 5: Assuming that data rate = 5 kbps and device SFO = 10%, if 3rd and 5th harmonics are avoided, when maximum R values are up to 256, the maximum number of multiplexed devices Y is 9.
Observation 6: Assuming that data rate = 5 kbps and device SFO = 10%, if 3rd is avoided, when maximum R values are up to 256, the maximum number of multiplexed devices Y is 10.
Observation 7: When CRC-6 is attached, for TBS = 24 bits, PUE is in the level of 10-7; for TBS = 56 bits, PUE is increased to 10-4.

Proposal 1: For D2R link, compared to FEC Option 1, FEC Option 2 can reduce encoding delay and storage cost at the device side, and the increased complexity at the reader side is acceptable. Thus, FEC Option 2 is supported.
Proposal 2: For D2R chip duration, the D2R chip duration can be selected from {133.33, 66.67, 33.33, 22.22, 16.67, 11.11, 8.33, 5.56, 4.17, 2.78, 2.08, 1.39, 1.04, 0.69} μs.
Proposal 3: The maximum SFS factor R can be up to 192.
Proposal 4: The values of SFS factor R can be selected from {1, 2, 4, 6, …, 192}.
Proposal 5: The maximum number of multiplexed devices Y can be up to 8.
Proposal 6: For R2D/D2R transmissions with CRC, the used CRC length depends on the number of bits X before CRC, i.e. CRC-6 for X<=24 bits, while CRC-16 for X > 24 bits.
Proposal 7: To determine when no CRC is used, support Option 1, i.e., a threshold of number of information bits Y is defined. FFS Y pending RAN2's progress. 

Chera3GPP TSG RAN WG1#120bis		R1-2502204
Wuhan, China, April 7th – 11th, 2025

Source:	Panasonic
Title: 	Discussion on Physical Channel Designs for A-IoT
Agenda Item:		9.4.2
Document for:	Discussion

Conclusions
In this contribution, we provided our views on physical channel designs for A-IoT. We made following proposals:
Proposal 1: R2D control information containing a target device ID should be easily distinguished from the data.
Proposal 2: The variable R2D control information sizes should be supported. 
Proposal 3: A separate CRC for R2D control information should be used.
Proposal 4: The CRC-16 should be used for a message with TBS larger than 56 bits.
Proposal 5: The CRC-6 should be supported at least for TBS between 8 and 56 bits.
Proposal 6: For TBS of less than 8 bits, either not to use CRC or reuse CRC-6.
Proposal 7: FFS whether to not CRC based on the reader indication or message type.
Proposal 8: For the data segmentation, the size of CRC should be determined for each message segment separately, according to the TBS of the segment.
Proposal 9: The head biting should be used for the initialization of CC registers.
Proposal 10: The code rates 1, 1/2, and 1/3, 1/6 are supported. The code rate 1 is achieved by no FEC. The code rate 1/2 is derived by puncturing the mother code rate 1/3. The code rate 1/6 is achieved by using 2 times repetition of the code rate 1/3. 

3GPP TSG-RAN WG1 Meeting #120bis	R1-2502234	
Wuhan, China, April 07-11, 2025

Agenda Item:	9.4.2
Source:	Huawei, HiSilicon
Title:	Physical channel design on channel coding
Document for:	Discussion and Decision

Conclusions
In this contribution, the physical channel design on channel coding for Ambient IoT is discussed and following observations and proposals are made accordingly.
Observation 1: For initialization of shift register with Option 1, the CRC attachment and the channel coding are required to be processed in the serial mode, which introduces an additional processing time delay.
Observation 2: For initialization of shift register with Option 2, the CRC attachment and the channel coding can be processed in a pipelined manner and hence do not incur any additional processing time. 
Observation 3: For Option 2, no additional memory is required since the CRC and channel coding can be performed in parallel while the output of the CRC needs to be saved in memory until the CRC attachment is finished for Option 1. 
Observation 4: The performance with Option 2 is the same with Option 1 and does not have an impact on the hardware design of the reader when using Option 2.
Observation 5: An interleaver requires buffering of the CC-encoded bits, requiring these bits to be written into non-volatile memory, which is power consuming and increases latency for the device.
Observation 6: Using a smaller buffer size would result in a smaller interleaving matrix, reducing its effectiveness and impact on the system performance.
Observation 7: If a device has to maintain a large buffer, it would have to perform the write operation more than once to perform interleaving, further increasing latency and power consumption.
Observation 8: Given the power consumption level of an Ambient IoT device, it is not possible for the device to support an interleaver with a large enough matrix to be effective, since it would be required to perform write operations more than once to buffer the CC-encoded bits, increasing the latency and power consumption beyond what is achievable for such a device. 
Observation 9: When R = 2n, FDMed devices with different R values will not be affected by the odd-harmonics interference.
Observation 10: When R = 2n and , there is no overlap between the main lobe.
Observation 11: In order to have a comparable peak D2R data rate with RFID, the maximum D2R transmission bandwidth of AIoT is 2.88 MHz.Observation 12: The set of R values include at least {1, 4, 8, 16, 32, 64, 128}.
Observation 13: The reader needs to indicate to the device the frequency domain resource which includes the D2R chip length and R and reader. The total indication overhead for Msg1 is  bits.
Observation 14: When Ymax is 8, one more R value needs to be selected other than {1, 4, 8, 16, 32, 64, 128}. For improving the spectrum utilization efficiency, the remaining R value can be selected as 96.
Observation 15: Although the main lobe of R = 96 will be affected by the 3rd harmonic interference caused by R = 32, the performance loss is marginal when FDMed devices use the same transmit power.
Observation 16: In order to avoid the counting error of samples introduced by non-integer samples, the D2R chip length is a multiple or a factor of the R2D chip length.
Observation 17: The minimum D2R chip length is 0.69 μs when the maximum D2R transmission bandwidth Btx,D2R is 2880 kHz.
Observation 18: The maximum D2R chip length is 133.33 μs when the minimum D2R transmission bandwidth Btx,D2R is 15 kHz.
Observation 19: For the A-IoT system, CRC-6 can realize reasonable undetected error probability performance under TBS = 24bits.
Observation 20: For the random-access procedure, Msg1 can use no CRC since the scheduling information can be determined by receiving Msg0 at the device
Observation 21: Higher-layer message type or purpose is not known to the physical layer beyond the defined steps of the random-access procedure. Attachment of CRC dependent on message type or purpose is a RAN2 decision, and would require specific procedural design for MAC to inform PHY.

Proposal 1: For D2R FEC, initialization of shift registers with Option 2 is supported.
If Option 1 is supported instead, the additional processing time for FEC+CRC needs to be considered in setting the minimum device timing requirements in 9.4.4.
Proposal 2: Sub-block interleaving is not supported by Ambient IoT devices.
Proposal 3: Applying or not applying FEC is explicitly indicated in the D2R scheduling information in Msg0 and is applicable for all the corresponding D2R transmissions.
Proposal 4: For bit collection after FEC, the output bits for each input bit are arranged sequentially in accordance with the input bits, i.e., for input bits , the output of the FEC is 
Proposal 5: For small frequency shifts, the values of R are selected using R = 2n.
Proposal 6: When R = 2n, the maximum value of R is 128 in consideration of the comparable D2R data rate with RFID of an A-IoT device.
Proposal 7: In consideration of indication overhead, the max value of Y is not larger than 8, and the candidate values are {1, 2, 4, 8}.
Proposal 8: The total set of values for R is {1, 4, 8, 16, 32, 64, 96, 128}.
Proposal 9: The following D2R chip lengths are supported:
The D2R chip lengths are {133.33 μs, 33.33 μs, 16.67 μs, 8.33 μs, 4.17 μs, 2.08 μs, 1.39 μs, 1.04 μs, 66.67 μs, 11.11 μs, 2.78 μs, 5.56 μs, 0.69 μs}.
Proposal 10: For the D2R transmission of Ambient IoT, the maximum repetition number for block repetition is 2. 
Proposal 11: For the A-IoT system, CRC 6 for TBSX, and CRC-16 for TBSX with X = 24 bits is supported.
Proposal 12: From the RAN1 perspective, both Option 1 with Y = 8 bits and Option 2 where the device transmits PDRCH for Msg1 upon receiving a PRDCH triggering random access are supported as the conditions for no CRC.

3GPP TSG RAN WG1 #120bis		R1-2502274
Wuhan, China, April 7th – 11th, 2025

Source:	OPPO 
Title:                     Discussion on physical channels design for A-IoT
Agenda Item:       9.4.2
Document for:	Discussion and Decision

Conclusion
In this paper, we discussed physical channel design for A-IoT, the following observations and proposals are given.
Proposal 1: A threshold of TBS can be pre-defined to determine whether CRC-6 and CRC-16 needs to be used.
Proposal 2: The following conditions are considered for no CRC:
PDRCH (including Msg 1) transmission from devices.
In case slot-aloha based transmission (no FDMA), PDRCH (including Msg 2) corresponds to one device.
Proposal 3: If L1 R2D control information is supported & carried by PRDCH, separate CRC is attached to L1 R2D control information and R2D data respectively is preferred. 
FFS whether same or different CRC length for R2D control information and data packet
Proposal 4: For the initial values of the shift register of the CC encoder, option 1 is supported. 
Option 1: The initial values of the shift register of the CC encoder are set to the values corresponding to the last (K-1) information bits defined in TS 36.212.
Note: K is the constraint length.
Proposal 5: Whether FEC module is used is controlled by reader. When FEC is not used, the coding rate of convolution code is 1. 
Observation 1: FDMA of D2R transmissions for device type 1 would be based on repetition of line codes, where the number of repetitions that can be supported for 15kHz are {1, 2, 4, 8, 16, 32, 64, 128}.
Observation 2:  Since the transmission bandwidth exists frequency overlap for repetition of 1 and 2, repetition of 2 should not be supported.
Observation 3: The guard band for FDMA of D2R transmission would not need to be defined in RAN1 and RAN4 (i.e., for backscattering device 1 and 2a), since small frequency shifts are achieved by line coding repetition and as long as the repetition numbers {1, 4, 8, 16, 32, 64, 128} would not cause unwanted interferences to each other (e.g., due to harmonics, inter-modulation).
Proposal 6: The supported set of codeword repetition number (R) for different D2R transmission bandwidths should be:
For 15kHz D2R bandwidth, R = {1, 4, 8, 16, 32, 64, 128}
For 30kHz D2R bandwidth, R = {1, 4, 8, 16, 32, 64}
For 60kHz D2R bandwidth, R = {1, 4, 8, 16, 32}
For 120kHz D2R bandwidth, R = {1, 4, 8, 16}
For 240kHz D2R bandwidth, R = {1, 4, 8}
For 480kHz D2R bandwidth, R = {1, 4}
For 960kHz D2R bandwidth, R = {1}

Proposal 7: For block level repetition of D2R transmission, the repeated blocks are transmitted via a single PDRCH. 

3GPP TSG RAN WG1 #120bis		R1-2502369 
Wuhan, China, April 7th – 11th, 2025 
Agenda item:	9.4.2
Source:	Samsung
Title:	Views on Physical channels design – line coding, FEC, CRC, repetition aspects
Document for:	Discussion and decision

Conclusion
In this contribution, we made the following observations and proposals:
Proposal 1: TBCC should be adopted as the baseline for D2R convolutional coding.
Observation 1: Given that no FEC is already supported in D2R, there is limited justification for introducing puncturing to achieve higher code rates.
Observation 2: Since block-level repetition has already been agreed upon, additionally repeating coded bits is unnecessary and redundant.
Proposal 2: Support only the 1/3 code rate for convolutional coding in D2R.
Observation 3: It can be difficult for the reader to determine whether each device is close enough to operate without FEC, based on proximity determination solution 1.
Proposal 3: The use of FEC is configured via A-IoT paging. It is assumed that all devices operate in the same manner with respect to FEC usage within the same inventory or command round.
Observation 4: Convolutional code with K=7 may not guarantee adequate decoding performance for a maximum TB size of 1,000 bits.
Proposal 4: When using convolutional coding for D2R, specify a maximum TB size smaller than 1,000 bits.
Observation 5: The decision on the value of X for CRC-6 vs. CRC-16 should be based on the error detection performance as well as the CRC overhead.
Observation 6: The main purpose of CRC is to ensure a correct reception of a message, which has more relevance with the importance of a message rather than the size itself.
Proposal 5: The criteria for having no CRC is based on R2D/D2R message types. 
Observation 7: If R2D control information is provided, it must have a separate CRC so that a device can first read R2D control information to acquire information necessary to read the following R2D data.  
Proposal 6: The R2D control information is attached with a separate CRC with a fixed length. 
Proposal 7: Specify the values or range of small frequency shift factors (R) for D2R data rates.
D2R data rate = 1/Tb, where Tb is the time duration corresponding to one bit after FEC, if applied
R = Tb/(2 × D2R chip length)
D2R chip rate = 2R/Tb 
Proposal 8: For D2R transmission with a small frequency shift, the R value should be a power of two (i.e., R=2n, n = 0, 1, …). 
Proposal 9: For D2R transmission with a small frequency shift, the maximum R value can vary depending on the data rate.
Proposal 10: Capture the table below to specify the available small frequency shift factors for different data rate. 

References:


Sinha, Satyajit. "State of IoT 2024: Number of connected IoT devices growing 13% to 18.8 billion globally." IoT Analytics (2024).
RP-243326 “New Work Item: Solutions for Ambient IoT (Internet of Things) in NR”. 

3GPP TSG RAN WG1 #120bis			R1-2502442
Wuhan, China, April 7th – 11th, 2025

Agenda Item:	9.4.2
Title:	Discussion on line coding, FEC, CRC and repetition aspects for Ambient IoT
Source:	Xiaomi
Document for:	Decision

Conclusion
This contribution discusses about channel coding aspects for Ambient IoT including line code, CRC, FEC and repetition, and the following observation and proposals can be concluded:
Observation
Observation 1: For D2R FDMA, R=2 and R=4 (M=4 and M=8), the interference between main lobes and side lobes from different devices has negative impact on FDMA performance.
Observation 2: For D2R FDMA, R=2 and R=6 (M=4 and M=12), and R=4 and R=6 (M=8 and M=12), the interference between main lobes and side lobes from different devices can be negligible.
Observation 3: D2R segmentation does not have impact on physical layer, including CRC attachment.

Proposals
Proposal 1: For D2R FDMA, the case of R=2 and R=4 (M=4 and M=8) is not selected.
Proposal 2: In Ambient IoT system, both PRDCH and PDRCH apply that TBS≤24bits with 6-bit CRC and TBS＞24bits with 16-bit CRC.
Proposal 3: In Ambient IoT system, for both PRDCH and PDRCH transmission, CRC attachment is performed by default.
Proposal 4: When L1 control is supported for R2D, separate CRC is used for L1 control and data in one R2D.
Proposal 5: In Ambient IoT system, for both PRDCH and PDRCH, no CRC case can be supported by considering TBS, message type. No CRC attachment can be determined or indicated by PRDCH.
Proposal 6: For D2R FEC, the final coding rate is the same as mother code with coding rate 1/3.
Proposal 7: For the initial values of the shift register of the CC encoder, Option 1 with LTE TBCC is supported.
Proposal 8: Discuss and potentially specify the condition(s) when FEC is used or not used by D2R.
Proposal 9: An explicit indication is carried by R2D control information to enable/disable D2R FEC.
Proposal 10: In Ambient IoT system, for PDRCH generation, repetition is performed after FEC.

3GPP TSG RAN WG1 #120bis				R1-2502475
Wuhan, China, April 7th – 11th, 2025

Agenda Item:	9.4.2
Source: 	LG Electronics
Title: 	A-IoT PHY layer design - line coding, FEC, CRC and repetition aspects
Document for:	Discussion and decision

Conclusion
	In this contribution, we shared our views on the PHY layer design aspects of line coding, FEC, CRC and repetition for Ambient IoT.
Proposal 1: For R2D, when the generated number of chips for the R2D transmission does not fully occupy the last OFDM symbol, padding is used.
FFS padding values/patterns
Proposal 2: For R2D with Manchester line coding, resource allocation unit can be defined based on one of the following:
chip(s)
line code codeword(s)
NR OFDM symbol(s)
Proposal 3: Based on the D2R chip duration provided by a reader, an A-IoT device determines the frequency shift value for D2R transmission.
The information on D2R chip duration can be carried in L1 R2D control (if supported), or in R2D payload.
Proposal 4: Based on the D2R chip duration and the FS factor provided by a reader, an A-IoT device determines the data rate (1/Tb) for D2R transmission.
The information on the FS factor can be carried in L1 R2D control (if supported), or in R2D payload.
Proposal 5: A D2R chip corresponds to one modulated symbol for OOK and BPSK.
The set of D2R chip duration values are determined considering the following aspects:
The minimum D2R chip duration should be comparable to or no larger than 1 / (640*2 kHz) = 0.78 us
The maximum D2R chip duration should be comparable to or no smaller than 133.33 us.
A D2R chip duration is an integer multiple or submultiple of an R2D chip duration
Proposal 6: The minimum D2R chip duration for Ambient IoT is 0.52 us
Proposal 7: The maximum D2R chip duration for Ambient IoT is 133.33 us
Proposal 8: For D2R chip duration indication, the set of D2R chip duration values to be predefined in the spec includes at least the following:
minimum D2R chip duration
maximum D2R chip duration
R2D chip duration values
Proposal 9: Small FS factor R is indicated in R2D control information from a predefined set of values.
The small FS factor R can be carried in L1 R2D control (if supported), or in R2D payload.
The set of small FS factor values are determined considering the following aspects:
Device sampling frequency
Maximum D2R chip duration (i.e., the minimum transmission bandwidth)
Device multiplexing capacity
Device SFO
Odd harmonics
Signaling overhead
Power consumption
Spectral efficiency
Proposal 10: The minimum small FS factor R for D2R transmission is 1
Proposal 11: The maximum small FS factor R for D2R transmission is 64
Proposal 12: For small FS factor indication, consider the following for the set of small FS factor values to be predefined in the spec:
Alt.1 small FS factor R = {1, 2, 4, 8, 16, 32, 64} (based on R = 2n, n = 0, 1, …)
Alt.2 small FS factor R = {1, 2, 4, 6, 8, 10, 12, 16} (based on R = 1 and 2m, m = 1, 2, …)
Proposal 13: Applying or not applying the FEC for D2R is indicated by a reader by an explicit indication (in L1 R2D control or R2D data), or by setting the code rate to 1
FFS in which R2D message, the indication is carried
Proposal 14: For D2R, the convolutional code rate other than 1/3 is NOT supported in Rel-19 Ambient IoT.
Other code rates can be supported in combination with block-level repetitions, e.g., with the support of repetition number 2 and 4, the combined code rates of {1/2, 1/3, 4/1, 6/1} can be supported. 
Proposal 15: The initial values of the shift register of the CC encoder for PDRCH transmission are set to the values corresponding to the last (K-1) information bits defined in TS 36.212. (Option 1)
Proposal 16: Considering the balance of overhead and probability of undetected error, when CRC is attached to a PRDCH or PDRCH transmission,
CRC-6 is used, when the number of information bits is ≤ 24 bits
CRC-16 is used, otherwise (i.e., when the number of information bits is > 24 bits) 
Proposal 17: Support both Option 1 and Option 2 of determining when no CRC is used.
On the specified condition(s) of Option 2, device determines when no CRC is used based on message/command type indication in L1 R2D control or R2D data
Proposal 18: Support L1 control information for PRDCH, i.e. Option 2.
Proposal 19: Support separate CRCs for PRDCH, i.e. the first CRC for L1 R2D control information and the second CRC for R2D data which may or may not contain L2 control information.
Proposal 20: Consider fixed size CRC for L1 R2D control (6 or 16) and variable size CRC for R2D data.
CRC size for R2D data to be determined based on the R2D data size, or to be signaled via L1 R2D control
Proposal 21: Consider aligning the end of L1 R2D control (if supported) with OFDM symbol boundaries if separate M values for L1 R2D control and R2D data are configured.
Padding may also be needed in this case.
Proposal 22: For D2R, consider the following alternatives to restrict the buffer size required to support block-level repetitions.
Alt.1) Support block-level repetitions for TBS < X (e.g., X = tens of bits)
Alt.2) Block-level repetitions with the block size smaller than the TBS
Alt.3) Do NOT support block-level repetitions (i.e., support bit-level type 2 and/or type 1) at least for Device 1
Proposal 23: Support the following two cases for D2R block level repetitions, one of which is indicated in R2D control information or determined based on the block size
The repeated blocks are transmitted via a single PDRCH 
The repeated blocks are transmitted via different PDRCHs
Proposal 24: Depending on the block size for D2R block repetition, N (>1) blocks (with or w/o FEC reset/initialization) per each PDRCH can also be considered.
Proposal 25: In the case of the single PDRCH for carrying repeated blocks, FEC may need to be reset/re-initialized at the start of each block to generate identical blocks of the coded bits.

3GPP TSG RAN WG1 #120bis	                                                                     R1-2502583
Wuhan, China, April 7th – 11th, 2025

Agenda Item:	9.4.2
Source: 	InterDigital, Inc.
Title:	Discussion on coding aspects of physical channel design for Ambient IoT
Document for:	Discussion and Decision
1. 

Summary
This contribution has discussed coding aspects of physical channel design for Ambient IoT. The following are proposed.
Proposal 1: For the small frequency shift factor R (i.e., the number of repeated Manchester codewords within Tb or number of square-wave periods within Tb),
R = 1 when no small frequency shift.
For R > 1, R = 2n.

Proposal 2: A D2R chip duration is determined by scaling a R2D chip duration.
Proposal 3: Support coding rate 1 for D2R.  
Proposal 4:  The initial values of the shift register of the CC encoder are set to the values corresponding to the last (K-1) information bits, i.e., tail biting convolutional code (TBCC) defined in TS 36.212.
Proposal 5: CRC-6 is used for payloads less than 24 bits and CRC-16 is used for payloads large than 24 bits.
Proposal 6: No CRC is used for payloads less than 8 bits.

3GPP TSG RAN WG1 #120bis		        R1-2502606
Wuhan, China, April 7th – 11th, 2025

Agenda Item:	9.4.2
Source:	Apple
Title:	On coding aspects for Ambient IoT
Document for:	Discussion/Decision

Conclusion
In this contribution, following observations/proposals have been made related to coding aspects for ambient IoT:
Proposal 1: For D2R transmission with frequency shift R/Tb, to maintain orthogonality with large sampling offset, alternative frequency shift can be used, i.e. R = 2n
For the case without repetition, R = 1 is also supported

Proposal 2: For PRDCH, CRC-16 is supported for paging message transmission considering more robustness for paging message as it is typically transmitted to multiple devices. 

Proposal 3: For PRDCH, if L1 R2D control information is transmitted separately from the R2D message, 
CRC-16 is used for the L1 R2D control information transmission.  
Depending on the R2D message size, either CRC-6 or CRC-16 can be used from the candidate values agreed in RAN1#120

Proposal 4: Adopt option 1 for the shift register initialization where the initial values of the shift register of the CC encoder are set to the values corresponding to the last (K-1) information bits defined in TS 36.212

3GPP TSG RAN WG1 #120-bis                                 R1-2502672
Wuhan, China, February 7th - 11th, 2025

Source:	Sharp
Title:	Discussion on coding aspects
Agenda Item:	9.4.2
Document for:	Discussion and Decision

Conclusion
In this contribution, we discuss a few coding aspects of the A-IoT physical layer channel design, and make the following observations and proposals.
A maximum amount of small frequency shift value (or, a corresponding smallest D2R chip length) should be discussed and decided in RAN1, taking into account the processing capability of Device 1.
For a number of FDM’ed D2R transmissions, the respective small frequency shift factor values (and corresponding D2R frequency resources) should be allocated such that they are spaced as far apart as possible.
In case CRC is attached to a PRDCH or PDRCH transmission, when the number of information bits is <= 24 bits, CRC-6 is used. Otherwise, when the number of information bits is > 24 bits, CRC-16 is used.
For L1 control information, if defined, CRC is always attached (either joint CRC attachment for L1 control information and higher layer payload, or separate CRC attachment).
Regarding the two options for no CRC,
Option 1 (i.e. when the number of information bits is ≤ Y bits, no CRC is used) is applied only when no other condition is met.
For Option 2, consider the following conditions:
For R2D or D2R, a few small TB sizes is reserved for no CRC.
For D2R, the higher layers determine whether to attach CRC or not for a particular message.
Each D2R transmission is associated with a small frequency shift factor value which is allocated in the D2R grant conveyed in the scheduling R2D transmission.
The small frequency shift factor value is one of the small frequency shift factor values pre-defined for the D2R bandwidth of the D2R transmission.
Each D2R chip duration is expressed as  where  is a pre-defined integer number.
RAN1 to discuss and agree upon a minimum D2R chip duration supported by A-IoT Device 1.
A set of D2R chip durations (or, one corresponding set of SFS factor values) is defined per D2R bandwidth (or, corresponding bit length).

3GPP TSG RAN WG1 #120bis		R1-2502691 
Wuhan, China, April 7th – 11th, 2025

Source:	HONOR
Title:	Discussion on Physical channels design for Ambient IoT– other aspects
Agenda Item:	9.4.2
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: For D2R FEC, support option 1 which the initial values of the shift register of the CC encoder are set to the values corresponding to the last (K-1) information bits, i.e., tail biting convolutional code (TBCC) defined in TS 36.212.
Proposal 2: Sub-block interleaving is not supported by Ambient IoT devices in Rel-19.
Proposal 3: For D2R FEC code rate, support {1, 1/2, 1/3} and indicated by reader via L1/higher layer control.
Proposal 4: For D2R block level repetition, only support repeated blocks are transmitted via a single PDRCH.
Proposal 5: For whether to use CRC, support both option 2 and option 1 in which for RA triggering Msg without resource allocation and ACK-like messages, no CRC is needed, and use 16 bits as the threshold when L1 can’t know the message type exactly.
Proposal 6: Use threshold X=24 to determine using CRC-6 or CRC-16 for both PRDCH and PDRCH.
Proposal 7: Consider to use separate L1 control CRC for some messages, such as Msg2.
Proposal 8: The maximum value of Y for FDMA should equal to or less than 8.
Proposal 9: For available R value, support Alt.1: A subset of R=2n.

Observation 1: Complexity additionally required for encoder is minor to support FEC code rate 1/2 by puncturing.
Observation 2: Repeated blocks transmitted via different PDRCH will increase the overhead and complexity.
Observation 3: Messages using CRC or not should consider the overhead and function and importance.

3GPP TSG RAN WG1 #120bis		R1-2502705
Wuhan, China, April 7th – 11st, 2025
Agenda item:	9.4.2
Source: 	MediaTek Inc.
Title: 	Discussion on A-IoT physical line coding, FEC, CRC, repetition aspects
Document for:	Discussion/Decision

Conclusion
Observation 1: The transmission efficiency, e.g., overhead and the reliability performance, e.g., undetected error probability should be considered as the metric for determining the threshold of using CRC-6 or CRC-16.
Observation 2: Regarding the utilization of CRC-6 or CRC-16, from the perspective of overhead, both X = 24 and X = 56 can achieve an overhead smaller than 40% due to the CRC attachment.
Observation 3: Regarding the utilization of CRC-6 or CRC-16, from the perspective of undetected error probability, X = 24 can achieve much better performance than X = 56.
Observation 4: Regarding the utilization of no CRC, from the perspective of overhead, both Y = 8 and Y = 16 can achieve an overhead no more than 40%.
Observation 5: Regarding the utilization of no CRC, from the perspective of functionality, in some specified conditions, no CRC is used, e.g., device transmits PDRCH for Msg. 1 upon receiving a PRDCH triggering random access, QueryRep-like transmission.
Observation 6: For some particular transmissions with information bit number  Y, using CRC attachment is still necessary.
Proposal 1: Regarding the utilization of CRC-6 or CRC-16, considering both overhead and reliability performance, Alt 1 of X = 24 is supported, i.e., when the number of information bits is ≤ 24 bits, CRC-6 is used. Otherwise, when the number of information bits is > 24 bits, CRC-16 is used.
Proposal 2: Both options are supported to determine when no CRC is used with one further clarification on option 1,
Option 1: A threshold of number of information bits 8 (i.e., Alt. 2, Y = 8). When the number of information bits is ≤ 8 bits, no CRC is used.
It does not preclude the use of CRC in particular condition(s) even the number of information bits is ≤ 8 bits. FFS particular condition(s).
Option 2: Specified condition(s), e.g., device transmits PDRCH for Msg. 1 upon receiving a PRDCH triggering random access, and QueryRep-like transmission.
Proposal 3: For D2R transmission, using or not using FEC is based on the reader indication in R2D control or D2R scheduling transmission.
Proposal 4: For D2R transmission, transmission bandwidth of RE level and RB level are supported.

3GPP TSG RAN WG1 #120bis	                      	 R1-2502752
Wuhan, China, April 7th – 11th, 2025

Agenda Item:	9.4.2
Source: 	ASUSTeK
Title:  	Discussion on A-IoT Physical channels design
Document for:	Discussion and Decision

Conclusion
In this contribution, we have following proposals for A-IoT physical channel design:
Proposal 1:  For PRDCH generation, L1 R2D control information and R2D data with separate CRC attachment are carried together in single PRDCH.
Proposal 2:  For PDRCH generation, not define L1 D2R control information and corresponding CRC attachment. 
Proposal 3:  For CRC attachment, the thresholds of number of information bits are applied to L1 R2D control information (if any) and R2D data separately.

3GPP TSG RAN WG1 #120bis							         R1-2502767
Wuhan, China, April 7th – 11th, 2025

Source:	NTT DOCOMO, INC.
Title:	Discussion on coding and CRC aspects of physical channel design for Ambient IoT
Agenda Item:	9.4.2
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.
R2D and D2R CRC
Proposal 1: For CRC for PRDCH and PDRCH, 6bit CRC is applied for TBS24bits, otherwise, 16bit CRC is applied.
Exception depending on message type, e.g., 16-bit CRC regardless of TBS for R2D L1 control, can be further discussed.
Proposal 2: For PDRCH, when the segmentation is applied, no RAN1 impact on CRC attachment is expected with the following understanding.
A segment is assumed as one TB from PHY layer perspective.
CRC is applied to each TB/segment separately.
CRC length is determined based on the TBS for each segment/TB separately.
Proposal 3: For PRDCH and PDRCH, no CRC can be used based on specified conditions, i.e., option 2 in the RAN1#120 agreement.
Note: On top of opt.2, opt.1 can be additionally applied.
Proposal 4: For PRDCH and PDRCH, CRC should be always applied regardless of TBS for the following cases:
R2D message which includes the target device ID and expects D2R transmission responding to the R2D
D2R data transfer after random access

D2R
Proposal 5: For small frequency shift of D2R transmission, discuss whether FDMA is supported for other D2R transmissions than Msg1 and Msg3.
Proposal 6: For the candidate values on small frequency shift for D2R, following aspects should be considered.
Impact of harmonics, which may require RAN4 expertise
Candidate values on information bit length Tb and chip length which are discussed in 9.4.1
Proposal 7: For the candidate values on small frequency shift for D2R, the value set of R where R = Tb/(2 × D2R chip length) should be specified in specification. At least 4 values of R should be supported and which values to use from the set of values should be up to reader implementation.
Proposal 8: For initialization on shift register of convolutional coding for PDRCH, the initial values of the shift register of the CC encoder are set to the values corresponding to the last (K-1) information bits defined in TS 36.212, i.e., option 1 in the agreement at the RAN1#120 should be supported.
Proposal 9: For FEC on PDRCH, other code rate than 1/3, e.g., 1/2 by puncturing, is not necessary.
Proposal 10: For D2R, FEC should be supported at least for data transfer after random access and Msg3.
FFS: Msg1 for contention free random access.
Proposal 11: For D2R block-level repetition, it should be clarified that repeated blocks are transmitted in one PDRCH.
Proposal 12: For D2R, block-level repetition should be supported at least for data transfer after random access and Msg3.
FFS: Msg1 for contention free random access. 
Proposal 13: For D2R, whether to apply block-level repetition should be controlled by reader.
Proposal 14: For D2R, for repetition factor of block-level repetition, it is not necessary to support multiple repetition factors, i.e., specify single value of repetition factor for D2R block-level repetition.
Observation 1: For D2R, 15 m coverage can be achieved with 5-7 kbps data rate.
Proposal 15: For D2R, for repetition factor of block-level repetition, consider maximum information bit length Tb and corresponding data rate.
Proposal 16: For D2R, for repetition factor of block-level repetition, 2 times repetition should be supported.

3GPP TSG RAN WG1 Meeting #120-bis               		        			R1-2502840
Wuhan, China, Apr 7 – 11, 2025

Source: Qualcomm Incorporated
Title: Physical channels design – line coding, FEC, CRC, repetition aspects
Agenda Item: 9.4.2
Document for: Discussion and Decision

Conclusion
Define Frequency shift as FS = 1/2*chip rate (Hz).
Bit rate and bit rate different (in general). Use term “bit rate” to describe frequency shift.
If devices with the same bit rate are FDMed, their frequency shift (FS) in Hz could be indicated by frequency shift factor R values.
Support D2R FDM of multiple devices with the same bit rate by indicating frequency shift based on frequency shift factor R values.
If devices with the different bit rate are FDMed, their frequency shift (FS) in Hz could be indicated by frequency shift factor R values and bit rates.
For frequency shift and FDM allocation, define nominal bit rate (bps) and , where .
For FDM of devices with the different bit rates, it is not straightforward to schedule devices in FS locations while ensuring the avoidance of other devices signal and their harmonics.
Any chip duration which is integer multiples of 1/640kHz (=1.5625us) will have integer number of samples for all three clocks of 1.28MHz, 1.92MHz, 2.56MHz.
The 1.28MHz clock cannot support chip rate larger than 1280kHz.
The 1.92MHz clock has 1.5 samples for chip rate of 1280kHz and 1 sample for 1920kMHz.
The 2.56MHz clock has 1.333 samples for chip rate of 1920kHz and 1 sample for 2560kHz.
Bit rates of 10kbps, 20kbps, 40kbps, 80kbps, 160kps, 320kbps, 640kbps can be supported by 1.28MHz clock.
Bit rates of 10kbps, 20kbps, 40kbps, 80kbps, 160kps, 320kbps, 640kbps, 1280kbps can be supported by 2.56MHz clock.
For a given bit rates, different R values could be supported. But the supportable maximum R value is limited by the clock speed. 
For D2R, consider one of following sets of rates.
Set 1
chip rates (kHz): 10, 20, 40, 80, 160, 320, 640, 1280
bit rates (kbps): 10, 20, 40, 80, 160, 320, 640
R values: 1,2,4, 8, 16, 32, 64
Set 2 
chip rates (kHz): 10, 20, 40, 80, 160, 320, 640, 1280, 2560
bit rates (kbps): 10, 20, 40, 80, 160, 320, 640, 1280
R values: 1,2,4, 8, 16, 32, 64, 128

Data rates are determined as follows.
If FEC is not used


If only FEC is used


If both FEC and D2R repetition are used


Convolutional code can be punctured to generate various code rates including 4/5, 2/3, 1/2, etc.
BLER performance of CC rate 1/2  and 1/3 are within 0.5 ~ 1dB.
Support multiple coding rates for D2R CC, e.g., 4/5, 2/3, 1/2, and/or 1/3.
For shift register initialization of CC encoder, support Option 1.
Support block level repetition by concatenating two blocks in back-to-back fashion.
CRC-6 is used for information size of up to 24 bits.
CRC-16 is used for information size of more than 24 bits.
Support message specific CRC attachment rule shown in the following table.
Table 5 Message specific CRC attachment rule

3GPP TSG RAN WG1 #120-bis                                                                                 R1-2502906
Wuhan, China, April 7th – 11th, 2025

Agenda Item:	9.4.2
Source:	Lenovo
Title:	Discussion on the Ambient IoT physical layer design aspects for Line coding, FEC, CRC, Repetition 
Document for:	Discussion 

Conclusion
Below is the summary of proposals and observations from our contribution.
Proposal 1: 3GPP Ambient IoT device type 1 normative work should target better design feature compared to UHF RFID to achieve better coverage: 
The design requirement should take into account, the maximum achievable clock accuracy which is primarily the target to design X-amble, D2R multiple access etc.,  
Maximum achievable clock accuracy after clock calibration for Ambient IoT device type 1 should be kept as 104 PPM for design target during normative phase. 

Proposal 2: Confirm Manchester line coding for PRDCH and PDRCH with bit-to-chip mapping of 0.5 code rate: bit 0→chips{10}, bit 1→chips{01}
Observation 1: For PDRCH Repetition before the FEC increases the usage of FEC, thereby increasing the power consumption and complexity.
Proposal 3:  For PDRCH repetition, support block repetition after the FEC 
Observation 2: Decreasing code rate provides marginal performance improvement as seen from the results captured in the TR 38.769

Proposal 4: For PDRCH coding, support constrained length of (k<6) and only two code rates ½, ¼  as multiple supported code rates increase the overhead of R2D control signal, complexity/power consumption at the device.

Proposal 5: RAN1 discuss FEC/no FEC signaling on the following aspects:
Use case: inventory only or inventory + command 
Paging trigger or RACH occasion trigger 
Restriction on message depending on the payload of each message: Msg1, Msg3, etc.,. 

3GPP TSG RAN WG1 #120bis	R1-2502930
Wuhan, China, April 7th – 11th, 2025

Agenda Item:	9.4.2
Source: 	ITL
Title: 	Coding aspects for Ambient IoT
Document for:	Discussion and decision

Conclusion
In this section, we summarize our observations and proposals on the coding aspects of physical layer design for Ambient IoT devices as follows:
Proposal 1: For the small frequency shifts of D2R transmission, support Manchester line codes with a repetition number R ≥ 1 with Option 1.
Proposal 2: For CRC length of R2D/D2R physical channels, it is preferred when the number of information bits is > 56 bits, CRC-16 is used for balanced overhead and probability of undetected error.
Proposal 3: Support block-level repetition for D2R transmission with following additional details:
Whether/how to determine the number of repetitions for D2R transmission via a device side based on various consideration aspects (e.g. received R2D signal power, use case, data QoS and so on)
Whether/how to enable early termination of repetition transmission

TDoc file unavailable

3GPP TSG RAN WG1 #120bis			R1-2503020
Wuhan, China, April 7th – 11th, 2025 


Source: 	Moderator (CMCC)
Title:	Summary #1 for coding aspects of physical channel design
Agenda:	9.4.2
Document for:	Discussion & Decision

Summary of proposals

Small frequency shift
#1 D2R chip duration

#2 SFS factor R


#3 Number of multiplexed devices


D2R FEC
#1 Initialization of shift register

#2 FEC code rate

#3 Bit collection

#4 Sub-block interleaving

D2R repetition
#1 Number of repetitions

#2 Understanding of block-level repetition


#3 Bit-level repetition


R2D/D2R CRC
#1 Case to use CRC-6 or CRC-16

#2 Case to use no CRC

#3 Joint or separate CRC

3GPP TSG RAN WG1 #120bis			R1-2503021
Wuhan, China, April 7th – 11th, 2025 


Source: 	Moderator (CMCC)
Title:	Summary #2 for coding aspects of physical channel design
Agenda:	9.4.2
Document for:	Discussion & Decision

Summary of proposals

Small frequency shift
#1 D2R chip duration

#2 SFS factor R


#3 Number of multiplexed devices


D2R FEC
#1 Initialization of shift register

#2 FEC code rate

#3 Bit collection

#4 Sub-block interleaving

D2R repetition
#1 Number of repetitions

#2 Understanding of block-level repetition


#3 Bit-level repetition


R2D/D2R CRC
#1 Case to use CRC-6 or CRC-16

#2 Case to use no CRC

#3 Joint or separate CRC

3GPP TSG RAN WG1 #120bis			R1-2503022
Wuhan, China, April 7th – 11th, 2025 


Source: 	Moderator (CMCC)
Title:	Summary #3 for coding aspects of physical channel design
Agenda:	9.4.2
Document for:	Discussion & Decision

Summary of proposals

Small frequency shift
#1 D2R chip duration

#2 SFS factor R


#3 Number of multiplexed devices


D2R FEC
#1 Initialization of shift register

#2 FEC code rate

#3 Bit collection

#4 Sub-block interleaving

D2R repetition
#1 Number of repetitions

#2 Understanding of block-level repetition


#3 Bit-level repetition


R2D/D2R CRC
#1 Case to use CRC-6 or CRC-16

#2 Case to use no CRC

#3 Joint or separate CRC

3GPP TSG RAN WG1 #120bis			R1-2503023
Wuhan, China, April 7th – 11th, 2025 


Source: 	Moderator (CMCC)
Title:	Summary #4 for coding aspects of physical channel design
Agenda:	9.4.2
Document for:	Discussion & Decision

Conclusion
RAN1 will not address the FFS in the agreement from RAN1#120:

Agreement
When CRC is attached to a PRDCH or PDRCH transmission, 
When the number of information bits is ≤ X bits, CRC-6 is used. Otherwise, when the number of information bits is > X bits, CRC-16 is used. Down-selection by RAN1#120bis from the following for X considering the balance of overhead and probability of undetected error:
Alt. 1: 24
Alt. 2: 56
FFS impact of segmentation, if any
Note: impact may not be in RAN1

3GPP TSG RAN WG1 #120bis			R1-2503
Wuhan, China, April 7th – 11th, 2025 


Source: 	Moderator (CMCC)
Title:	Summary # for coding aspects of physical channel design
Agenda:	9.4.2
Document for:	Discussion & Decision

Conclusion
RAN1 will not address the FFS in the agreement from RAN1#120:

Agreement
When CRC is attached to a PRDCH or PDRCH transmission, 
When the number of information bits is ≤ X bits, CRC-6 is used. Otherwise, when the number of information bits is > X bits, CRC-16 is used. Down-selection by RAN1#120bis from the following for X considering the balance of overhead and probability of undetected error:
Alt. 1: 24
Alt. 2: 56
FFS impact of segmentation, if any
Note: impact may not be in RAN1

3GPP TSG RAN WG1 #120bis			R1-25037
Wuhan, China, April 7th – 11th, 2025 


Source: 	Moderator (CMCC)
Title:	Summary #6 for coding aspects of physical channel design
Agenda:	9.4.2
Document for:	Discussion & Decision

Conclusion
RAN1 will not address the FFS in the agreement from RAN1#120:

Agreement
When CRC is attached to a PRDCH or PDRCH transmission, 
When the number of information bits is ≤ X bits, CRC-6 is used. Otherwise, when the number of information bits is > X bits, CRC-16 is used. Down-selection by RAN1#120bis from the following for X considering the balance of overhead and probability of undetected error:
Alt. 1: 24
Alt. 2: 56
FFS impact of segmentation, if any
Note: impact may not be in RAN1