R1-2600155
discussion
HARQ related aspects for 6GR
From Huawei
Summary
This Huawei contribution (R1-2600155) presents 27 proposals and 20 observations on HARQ design for 6G Radio (6GR), advocating for the inheritance of several 5G NR HARQ mechanisms while proposing new studies for enhancements. The document covers physical layer HARQ-ACK signaling, carrier aggregation feedback, codebook design, CBG-based retransmission, HARQ process management, and processing timelines, alongside new directions for improved link adaptation, faster and more reliable feedback, enhanced process management for larger bandwidth/antennas, and support for AI/immersive service traffic characteristics.
Position
Huawei proposes reusing 5G NR L1 HARQ-ACK UL control signaling, DL CA HARQ-ACK feedback on a single UL PUCCH carrier, and NR Type I/II HARQ-ACK codebooks as a starting point for 6G. They propose inheriting NR CBG-based retransmission and the configurable number of HARQ processes with asynchronous operation. They propose studying enhanced HARQ mechanisms for improved link adaptation to mitigate improper MCS assignment and studying SBFD, simplified dynamic TDD, and dynamic PUCCH carrier switching to achieve fast HARQ-ACK feedback. They propose studying mechanisms to improve HARQ-ACK reliability by addressing DCI miss detection and UCI detection failure. They propose studying HARQ process management considering larger bandwidth, higher antenna numbers, and flexible TB/CW-to-layer mapping, as well as studying HARQ design to accommodate error tolerance and priority differentiation for AI and immersive services.
Key proposals
- Proposal 1 (Sec 2): For 6GR HARQ-ACK UL reporting, reuse L1 UL control signalling as in NR.
- Proposal 2 (Sec 2.2): For 6G, reuse the 5G baseline where the HARQ-ACK feedback for PDSCHs in multiple DL CCs is sent using the PUCCH in a single UL carrier.
- Proposal 3 (Sec 2.3): For 6G codebook design, NR Type I/II HARQ-ACK codebooks are considered as starting point.
- Proposal 4 (Sec 2.4): For 6G, the NR CB(G)-based operation is inherited.
- Proposal 5 (Sec 2.5): For HARQ process management, the following is inherited from 5G: configurable number of HARQ processes, asynchronous HARQ operation with flexible (re-)transmission indication.
- Proposal 6 (Sec 2.6): The PDSCH decoding and PUSCH preparing procedure time should be defined, and the associated processing times of PDSCH and PUSCH need to be studied considering different UE capabilities and/or power states in 6GR.
- Proposal 7 (Sec 3.1): Study HARQ mechanism to support improved link adaptation to mitigate the impact of improper MCS assignment.
- Proposal 8 (Sec 3.2): Consider using SBFD, simplified dynamic TDD, and dynamic PUCCH carrier switching among all available UL carriers, in order to achieve fast HARQ-ACK feedback.
- Proposal 9 (Sec 3.3): Study mechanisms to improve the reliability for HARQ-ACK feedback, by addressing or mitigating the impact due to miss detection of DCI at the UE or UCI at the BS.
- Proposal 10 (Sec 3.4): Study HARQ process management in 6G considering larger bandwidth, higher number of antennas, and flexible mapping between TB/ (CW) and layer with respect to HARQ process(es).
- Proposal 11 (Sec 3.5): Study HARQ design to accommodate the error tolerance and data traffic with different characteristics, e.g., different priorities.
- Proposal 17 (Sec 4): For 6GR HARQ-ACK UL reporting, re-use L1 UL control signalling as in NR.
- Proposal 19 (Sec 4): For 6G codebook design, NR Type I/II HARQ-ACK codebooks are considered as starting point.
- Proposal 25 (Sec 4): Study mechanisms to improve the reliability for HARQ-ACK feedback, by addressing or mitigating the impact due to miss detection of DCI at the UE or UCI at the BS.
- Proposal 27 (Sec 4): Study HARQ design to accommodate the error tolerance and data traffic with different characteristics, e.g., different priorities.