3GPP TSG RAN WG1 #120bis R1-2503117
Wuhan, China, April 7th β 11th, 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.
[120bis-R19-Broadcast] Email discussion on Rel-19 LTE-bad 5G Broadcast Phase 2 β 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
R1-2502548 Higher layer parameters for Rel-19 LTE-based 5G Broadcast after RAN1#120 EBU
Time-frequency interleaver design for MBMS dedicated cells
R1-2501912 Discussion on time-frequency interleaver design for LTE-based 5G Broadcast ZTE Corporation, Sanechips
R1-2502209 On time-frequency interleavers for LTE-based 5G Broadcast Huawei, HiSilicon
R1-2502390 Views on LTE-based 5G broadcast Samsung
R1-2502546 Further details onΒ open issues regarding TFI for LTE-based 5G Broadcast EBU
R1-2502582 Design of Time-frequency interleaver for 5G Broadcast Shanghai Jiao Tong University
R1-2502861 Time and Frequency Interleaving for 5G Broadcast Qualcomm Incorporated
R1-2503001 FL summary#1 on Rel-19 LTE-based 5G Broadcast Phase 2 Moderator (EBU)
Agreement
Support at least the following values of time interleaver depth:
Values M={4,8,16,32} and N={1,2,4,8,16} are supported.
FFS: UE behaviour in case values of M and N exceed UE capabilities in terms of soft buffer size and maximum TBS supportable in a TTI
FFS: larger values, including M=64, N={32,64}.
R1-2503002 FL summary#2 on Rel-19 LTE-based 5G Broadcast Phase 2 Moderator (EBU)
Agreement
In case of time interleaving, in order to reduce the resource wastage due to the potential mismatch between MSI periodicity and the (MxN) pattern:
Adopt an extended set of configurable periodicities for MCH scheduling period for R19 PMCHs that includes the intermediate values among the periodicities defined for the legacy configurations.
May include the case of scheduling different M/N within the same MSI periodicity
FFS the values of the new periodicities.
RAN1 to specify UE behavior, if needed, in case of residual mismatch even after new periodicities are adopted, taking into account the amount of subframe available at the end of the periodicity
Option 1: Drop the time-interleaved TBs which do not have all the N RVs transmitted within the MSI periodicity
Option 2: Drop the time-interleaved TBs which could not be successfully decoded.
It is up to network to decide whether to schedule or not schedule MTCH transmission in the residual mismatch part of the MSI periodicity. UE knows this from MSI (legacy behaviour)
Other Options not precluded
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
The following steps are applied to the rows of the frequency interleaver:
Perform inter-row permutation with a reorder of the row indexes , which is calculated as:
With, , and
Perform a cyclic shift to the elements in the j-th row with an offset S(j) defined as:
R1-2503003 FL summary#3 on Rel-19 LTE-based 5G Broadcast Phase 2 Moderator (EBU)
Agreement
LBRM parameters (e.g. ) are consistent between the broadcast network and the (multiple) UEs that are receiving the broadcast transmission.
These multiple UEs may belong to different UE categories, thus having different values of , .
FFS: how the consistent NIR and NCB is calculated
Agreement
The agreement in the previous meeting is updated as follows:
Regarding configuration for time interleaving transmission, the following options can be considered:
- Option 1: Per PMCH configuration, e.g., via pmch-Config
- Option 2: Per MBMS session, e.g., via MBMS-SessionInfo or via MAC CE
- Alt1: If per MBMS session configuration is done, a T_proc of 3 ms between the end of the MSI and the first MTCH in the MCH scheduling period is needed for UE de-rate matching.
- Alt2: If per MBMS session configuration is done, other options (than Alt1 above) are not precluded, e.g. that allow the UE to know the M, N values of the first MTCH scheduled after the MSI
Agreement
Obtain the initial TBS (ππ΅πβ²) as per current specifications, and calculate the final TBS as ππ΅π=πππ’ππ{ππ΅πβ²Γπ}
The operation βround{x}β is mapping x to the closest TBS from all the existing TBS values in section 7.1.7.2 TS 36.213.
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