Spreadtrum · 10.5.4.3

Spreadtrum proposes simplifying 6G HARQ timing by introducing a single reference time and one point for HARQ-ACK on PUCCH and UCI mapping on PUSCH, arguing against NR's complex symbol-level overlap checking with variable PUCCH resource sets and PRI-based resource determination that changes within the same slot. They recommend retaining DCI-indicated slot offset K1 for DL HARQ feedback timing while advocating for a single basic PDSCH/PUSCH processing time per device type, with additional relaxation for energy efficiency and large bandwidth configurations (e.g., 200 MHz or 400 MHz). For codebook design, they propose continuing Type-2 HARQ-ACK codebook with enhancements to address the last DCI issue and inter-cell DAI coordination dependency, while reducing the total number of codebook types from five. They additionally propose studying cross-carrier HARQ retransmission for the Gothia cell multi-carrier architecture and DCI-based UL faster ARQ retransmission indications triggered by HARQ process failure status.

Spreadtrum/UNISOC proposes studying a unified and integrated scheduling framework that natively supports all combinations of dynamic scheduling schemes (single-slot, repetition, multi-PDSCH/PUSCH, multi-cell, and multi-cell multi-PDSCH/PUSCH). They propose reducing the number of HARQ-ACK codebook types from the current five in NR, specifically addressing pain points such as Type-1's large feedback bits and complex generation, Type-2's last DCI issue and inter-cell coordination dependency, and the complexity of enhanced Type-2 for two PDSCH groups. They propose adopting a single basic PDSCH/PUSCH processing time per device type as the starting point, eliminating the dual-capability structure of NR, while also proposing differentiated processing times for diverse device types and further study on relaxation for energy efficiency and large bandwidth configurations. They propose studying L1-based dynamic indication for faster ARQ retransmission triggered by HARQ process status, requiring definition of the previous TB associated with a HARQ process ID. They propose cross-carrier HARQ retransmission within the Multi-Carrier Single Cell (MCSC) architecture, where an initial transmission on one carrier can be retransmitted on another carrier within the same cell.