R1-2601822
discussion
Discussion on uplink WUS and operation
From Spreadtrum
Spreadtrum's prior position on
10.6.2
at
RAN1#124
· AI-synthesized, paraphrased
verify sources →
Proposes a single unified design for UL WUS to meet different on-demand signal requirements in 6G. Requires on-demand SIBx to be supported from 6G Day 1 using 5G NR legacy mechanisms including PRACH with dedicated preambles/resources for UL WUS, RAR MAC PDU subheader with RAPID for NW acknowledgement, Msg3 carrying system information request, or RRC signaling for connected UEs, citing successful 5G commercialization and limited negative UE impact. Proposes delaying UL WUS discussion for on-demand SIB1 and on-demand SSB in idle state until feasibility and necessity are evaluated in AI 10.5.1.1. Supports immediate adoption of on-demand SSB for SCell with NW triggering and no UL WUS using the Rel-19 legacy solution, characterizing it as a good balance between NW energy efficiency and UE performance for synchronization and measurement purposes.
Summary
Spreadtrum/UNISOC presents 9 proposals and 2 observations discussing UL WUS for 6G on-demand SI/SSB triggering. The document analyzes necessity and feasibility per deployment scenario, advocating study of UL WUS for SIB1/SIBx/SSB in specific cases, and proposes PRACH as a unified design starting point.
Position
Spreadtrum/UNISOC proposes studying UL WUS for on-demand SIB1 in DS#1b and DS#2b, on-demand SIBx in DS#1c, and on-demand SSB/SIB1 in DS#2a under the assumption of good inter-carrier synchronization. They argue DS#1a is infeasible due to lack of UE discovery and measurement signals, and DS#2c should be merged into DS#1c as it is not a valid separate multi-cell scenario. They support a unified UL WUS design with PRACH as the starting point for its robustness against CTO/CFO and coverage. They suggest importing the Rel-17 on-demand SSB for SCell (NW-triggered, no UL WUS) into 6G Day 1, and delay multi-TRP UL WUS discussion.
Key proposals
- Proposal 1 (Sec 2.1.1): On-demand SSB for scell can be considered in 6GR Day1. The legacy mechanism of NW triggering in 5G NR can be considered as the starting point.
- Proposal 2 (Sec 2.1.1): Study necessity and feasibility of UL WUS for requesting on-demand 6GR synchronization signals/PBCH, on-demand SIB1, and on-demand SIBx, considering NW/UE energy, latency, RRC states, complexity, coverage, synchronization performance, and deployment scenario.
- Proposal 3 (Sec 2.1.2): Suggest to delay the discussion on UL WUS under multi-TRP deployment scenario.
- Proposal 4 (Sec 2.2): For DS#1b, UL WUS can be studied to trigger on-demand SIB1.
- Proposal 5 (Sec 2.2): For DS#1c, UL WUS can be studied to trigger on-demand SIBx.
- Proposal 6 (Sec 2.2): For DS#2a, UL WUS can be studied to trigger on-demand SSB/SIB1, with the assumption of good synchronization between cell/carrier#1 and cell/carrier#2.
- Proposal 7 (Sec 2.2): For DS#2b, UL WUS can be studied to trigger on-demand SIB1.
- Proposal 8 (Sec 2.3): Support to strive one unified design of UL WUS.
- Proposal 9 (Sec 2.3): For the study of the design of UL WUS, PRACH can be considered as the starting point.
- Observation 1 (Sec 2.2): It seems to be not feasible for DS#1a, given that there is no signal for UE to discover, and measure the standalone cell.
- Observation 2 (Sec 2.2): DS#2c is not needed, and it can be merged into DS#1c.