R1-2601786
discussion
Discussion on 6G Uplink WUS and Operation
From FUTUREWEI
FUTUREWEI's prior position on
10.6.2
at
RAN1#124
· AI-synthesized, paraphrased
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Proposes maximizing 6G network energy saving by supporting UL WUS in any RRC state and in standalone cells/carriers, removing 5G NR constraints that limited on-demand SSB to SCell operation and on-demand SIB1 to cells with an assisting Cell A. Recommends adopting Rel-19 UL-WUS non-standalone operation as a baseline when a supporting cell is available. Proposes a new light Sync Signal design with sequence-based structure to indicate UL WUS configuration, beam/Sync Signal index, and LSBs of SFN, arguing that preconfigured UL WUS configuration limits network flexibility in Sync Signal placement and that MIB-based configuration fails to reduce initial access latency under long Sync Signal periodicity. Further proposes UL WUS occasion definitions that account for coarse UE timing synchronization and support both window-based association for long preambles and one-to-one association for short preambles depending on timing information availability.
Summary
Futurewei's contribution discusses UL WUS as an enabler for on-demand SS/PBCH/SIB1 operation in 6G, analyzing six deployment scenarios (DS#1a-c, DS#2a-c) and making 5 proposals and 11 observations regarding feasibility, configuration acquisition, and design aspects.
Position
Futurewei frames UL WUS primarily as an operational enabler for on-demand SS/PBCH/SIB1 rather than a standalone waveform design topic. They propose prioritizing the study of on-demand SIB1 using UL WUS in DS#1b and DS#2, and studying SIB1 time adaptation in DS#1c and DS#2c. They question the practical utility of DS#1a and propose RAN1 discuss whether it should be supported at all, deeming DS#1b/1c and DS#2 as the practical priority. For standalone deployment scenarios, they propose studying UL WUS configuration acquisition via light synchronization signaling with sequence-based structure that can indicate a predefined UL WUS configuration index, while also studying beam/index identification in the UL WUS request to allow the BS to limit on-demand response to a subset of beams.
Key proposals
- Proposal 1 (Sec 4.1.1): RAN1 should discuss and decide whether Scenario DS#1a should be supported.
- Observation 3 (Sec 4.1.2): Scenario DS#1b is feasible and may trigger SSB and/or SIB1 transmission or time adaptation.
- Observation 4 (Sec 4.1.3): Scenario DS#1c is feasible and may trigger SSB and/or SIB1 time adaptation.
- Observation 5 (Sec 4.2): If collocated, timing/power assumptions may be simplified; if non-collocated, these assumptions require explicit study.
- Observation 6 (Sec 4.2.1): Scenario DS#2a is feasible and is like on-demand SSB defined for NES in Rel 19.
- Observation 7 (Sec 4.2.2): Scenario DS#2b is feasible and is like on-demand SIB1 defined for NES in Rel 19.
- Observation 8 (Sec 4.2.3): Scenario DS#2c is feasible and suitable for on-demand SSB/SIB1 time adaptation.
- Observation 9 (Sec 5): For DS#1, UL WUS target coverage should match the standalone-cell service area. For DS#2, the target coverage depends on whether UL WUS is transmitted to cell/carrier #1 or #2.
- Observation 10 (Sec 5): For DS#2, UL WUS may be considered in all RRC states, while its necessity appears strongest in IDLE/INACTIVE.
- Observation 11 (Sec 5): DS#1b/1c and DS#2 are the practical priority, and DS#1a is conditional / advanced study.
- Proposal 2 (Sec 5): Study on-demand SS/PBCH including time adaptation of SS/PBCH using UL WUS in DS#1/DS#2.
- Proposal 3 (Sec 5): Prioritize the study of on-demand SIB1 using UL WUS in DS#1b and DS#2, and study SIB1 time adaptation in DS#1c and DS#2c.
- Proposal 4 (Sec 5): For DS#1, study UL WUS configuration acquisition from a light synchronization signaling, considering impact on access latency, and UE complexity.
- Proposal 5 (Sec 5): For UL WUS operation, study at least trigger conditions, synchronization assumption, UL WUS power determination, and whether the request can identify a beam/index, so the BS limits the OD response to a subset of beams.