3GPP TSG RAN WG1 #121 R1-2504899
St Julian’s, Malta, May 19th – 23th, 2025
Agenda Item: 9.13
Source: Ad-Hoc Chair (Huawei)
Title: Session notes for 9.13 LTE-based 5G Broadcast Phase 2
Document for: Discussion, Decision
LTE-based 5G Broadcast Phase 2
Please refer to RP-250794 for detailed scope of the WI for LTE-based 5G Broadcast Phase 2.
Rapporteur to provide initial input on higher layer signalling under agenda item 9.13. For input on higher layer signalling from any other source, please include it as part of your tdoc to relevant sub-agenda items.
[121-R19-Broadcast] Email discussion on Rel-19 LTE-bad 5G Broadcast Phase 2 – Jordi (EBU)
To be used for sharing updates on online/offline schedule, details on what is to be discussed in online/offline sessions, tdoc number of the moderator summary for online session, etc
R1-2503609 Further discussion on Time-frequency interleaver for 5G Broadcast Phase 2 Shanghai Jiao Tong University
R1-2504652 Higher layer parameters for Rel-19 LTE-based 5G Broadcast after RAN1#120 EBU
Time-frequency interleaver design for MBMS dedicated cells
R1-2503249 On time-frequency interleavers for LTE-based 5G Broadcast Huawei, HiSilicon
R1-2503332 Discussion on time-frequency interleaver design for LTE-based 5G Broadcast ZTE Corporation, Sanechips
R1-2503589 Further details on Time and Frequency Interleaving for 5G Broadcast phase-2 Samsung
R1-2504241 Further discussion on open issues regarding TFI for LTE-based 5G Broadcast EBU
R1-2504417 Time and Frequency Interleaving for 5G Broadcast Qualcomm Incorporated
R1-2504654 Time and Frequency Interleaving for 5G Broadcast Qualcomm Incorporated
R1-2504732 FL summary#1 on Rel-19 LTE-based 5G Broadcast Phase 2 Moderator (EBU)
Agreement
For each CB of the TB, , where (as per TS 36.212), and is the redundancy version of the n-th subframe, where , and, values are mapped sequentially to subframes, i.e., .
Agreement
Time interleaving parameters are indicated per PMCH configuration, e.g., via a configuration of in pmch-Config. Specify the following set of new MSI periodicities: {rf7, rf14, rf53, rf56, rf112, rf424}.
Additionally down-select among {rf27 or rf28}, {rf106 or rf108}, {rf211 or rf212}.
FFS actions on the residual mismatch after applying the new MSI periodicities in conjunction with the configuration of
Option 1: Fill the residual space with a service with different TFI configuration , e.g., via an additional (addressing the residual space) configuration via pmch-Config
Agreement
The soft buffer size for one time-interleaved TB is down-selected from
Option 1: , where:
Option 1a: is the soft buffer size pertaining to a reference UE category, M is the number of TBs for time-interleaving and is a scaling factor. FFS: exact value/values/configuration of .
Option 1b: is configured in PMCH-Config from {1827072, 3654144, 5481216, 7308288, 9744384, 12789504, 14616576, 17052672, 19488768, 24360960, 29233152, 34105344, 36541440, 38977536, 42631680, 47431680, 303562752}, is configured in PMCH-Config from: {1, 3/2, 6/5, 8/5, 2, 12/5, 8/3, 3, 5, 32}; and M is the number of TBs for time-interleaving.
Option 2 : The soft buffer size for the code block is denoted as , where and are same as defined in TS 36.212 clause 5.1. is calculated based on, e.g., , , N.
FFS: Details of determining (e.g., based on a notion of maximum coding rate) may need to be considered, to provide the flexibilities afforded by the LTE specifications, keeping in mind the LTE UE categories.
FFS: impact to soft buffer size for UE receiving unicast considering the case where UE prioritizes receiving broadcast.
Agreement
Confirm the working assumption in the following agreement:
Agreement
The number of columns, , of the frequency interleaver is , where denotes the number of CBs in the TB (including scaling, if any), denotes the number of OFDM symbols of the PMCH,
Working assumption:
m = , and denotes the operation to compute the greatest common divisor.
Agreement
For PMCH with time interleaving, the maximum TBS a UE supports for the scaled TB is down-selected from the following:
Option 1: the largest TBS among the multiple maximum TBS of a DL-SCH as per TS 36.306 set by UE category.
Option 2: the smallest TBS among the multiple maximum TBS of a DL-SCH as per TS 36.306 set by UE category.
Option 3: signalled by the UE from the multiple maximum TBS of a DL-SCH as per TS 36.306 set by UE, e.g. using a new UE capability
R1-2504733 FL summary#2 on Rel-19 LTE-based 5G Broadcast Phase 2 Moderator (EBU)
Agreement
Add the following MSI periodicities to the previous RAN1 agreement {rf28, rf108, rf212}.
Agreement
The residual space created by the mismatch between (M,N) and the MSI periodicity may be filled with the last MTCH service with different TFI configuration , e.g., via an additional (addressing the residual space) optional configuration via pmch-Config.
In the space before mismatch, all MTCHs within the MSI period have the same (M,N) obtained via the configuration of in pmch-Config.
Agreement
The soft buffer size for one time-interleaved TB is down-selected from
Option 1: , where:
Option 1a: is the soft buffer size pertaining to a reference UE category, M is the number of TBs for time-interleaving and is a scaling factor configured from network among values in the interval [0 1]. FFS: the exact values in the interval.
Option 1b: is configured in PMCH-Config from {1827072, 3654144, 5481216, 7308288, 9744384, 12789504, 14616576, 17052672, 19488768, 24360960, 29233152, 34105344, 36541440, 38977536, 42631680, 47431680, 303562752}, is configured in PMCH-Config from: {1, 3/2, 6/5, 8/5, 2, 12/5, 8/3, 3, 5, 32}; and M is the number of TBs for time-interleaving.
FFS: impact to soft buffer size for UE receiving unicast considering the case where UE prioritizes receiving broadcast.
Agreement
The number of subframes used for time-interleaving derived from ‘stop MTCH (x+1)’ is expected to be an integer multiple of MxN.
FFS: spec impact, if any
R1-2504734 FL summary#3 on Rel-19 LTE-based 5G Broadcast Phase 2 Moderator (EBU)
Agreement
Cyclically shift the bit sequence in Section 6.3.1 of TS 36.211 for the subframe of the time-interleaved TB by bits, where
,
denotes the number of subframes to which the time-interleaved TB is mapped
is
Alt 1: , with
is the number of bits in the codeblock within a subframe (as defined in TS 36.212)
Alt 2: , with
denotes the number of OFDM symbols within a subframe
denotes the number of CBs in the time-interleaved (scaled) TB
is the number of bits in the codeblock within a subframe (as defined in TS 36.212)
A new RRC parameter configures between and as above
If this new RRC parameter is not configured, the cyclic shift described in this agreement is not enabled.
A new optional UE capability is introduced to indicate support of this cyclic shift.
FFS: Extension of the bit-field corresponding to this RRC parameter by one additional bit, based on NOTE 1 below
NOTE 1: The following alternative for may be considered, exclusively based on BLER-vs-SNR performance comparison (with respect to Alt 1 / Alt 2)
, with
Where is the number of subcarriers available in 1 OFDM symbol for PMCH, e.g.
Agreement
The soft buffer size for one time-interleaved TB is calculated as , where is the soft buffer size configured according to a reference UE category, indicated from among { DL Cat4, DL Cat5, … DL Cat26}, M is the number of TBs for time-interleaving and β is configured from: {1/32, 1/5, 1/3, 3/8, 5/12, 1/2, 5/8, 5/6, 2/3, 1}.
Agreement
Rel-19 IE in MBMS Interest Indication message carries following parameters utilized for receiving Rel-19 LTE-based 5G Broadcast service(s):
Frequency
New values of sub-carrier spacing = {2.5 kHz, 1.25 kHz}
New values for bandwidth = {n30, n35, n40}
A new UE baseband resource Scaling factor (e.g., utilized soft buffer at the UE) used for receiving the time interleaved broadcast
Agreement
In case the time interleaved PMCH transmission (as configured) exceeds a UE’s capability(/es) in terms of soft buffer size or maximum TBS supported in a TTI, the UE is not expected to receive the corresponding time interleaved PMCH transmission.
Agreement
Update of the FFS of a previous agreement:
Agreement
The number of subframes used for time-interleaving derived from ‘stop MTCH (x+1)’ is expected to be an integer multiple of MxN.
Spec impact is up to RAN2.
Agreement
RAN1 asks RAN2 whether/how to address the HARQ handling in the MAC specification for the Rel-19 time-interleaved PMCH transmission with M TBs and N RVs.
Agreement
For clarification to RAN2:
When time-interleaving is enabled, values of N for configuration/indication do not include N=1. When N is not configured, time-interleaving is disabled i.e. N=1.
R1-2504921 RAN2 aspects on LTE-based 5G Broadcast Phase 2 EBU
R1-2504922 RAN2 aspects on LTE-based 5G Broadcast Phase 2 RAN1, EBU
Comeback draft LS – Jordi (EBU)
|