R1-2600158
discussion
WUS operation in RRC states
From Huawei
Summary
This document from Huawei discusses design principles and procedures for 6G DL WUS (Wake-Up Signal) across RRC idle and connected states, providing 11 observations and 10 proposals. It focuses on capacity improvements, single solutions for connected-state WUS procedures, measurements by low-power receivers, and performance evaluations showing significant energy savings (up to 70.2%) with trade-offs in latency.
Position
Huawei proposes studying 6G DL WUS with finer wakeup granularity than 5G LP-WUS in RRC idle state to reduce false wake-up rate and enable per-UE indication triggering RACH procedure directly. They require a single DL WUS procedure for RRC connected state, arguing that 5G-A LP-WUS Option 1-1 and Option 1-2 achieve similar energy consumption and latency performance when configured with identical key parameters (monitoring periodicity, monitoring duration), making two procedures redundant. They propose offloading RRM measurements including neighbour cell measurements to the LR, noting that more power saving gain can be obtained if LR supports more measurements, while requiring study of the impact on LR complexity to maintain acceptable measurement accuracy. They strive for a unified synchronization signal for MR and LR, observing that LR is OFDM-based so no dedicated LR synchronization signal is needed, but acknowledge different synchronization accuracy due to different RX number assumptions (LR with 1RX or 2RX vs MR with 4RX). They propose studying DL WUS for triggering per-UE fast transition from low-power sub-state to data-transmission sub-state in RRC connected state, and examining whether DL WUS can carry functionalities beyond wake-up such as PO clustering information for network energy saving or parameter updating, with evaluation criteria including power impact, coverage performance, and bit capacity.
Key proposals
- Proposal 1 (Sec 2.1): Study 6G DL WUS with finer wakeup granularity (than 5G LP-WUS) in RRC idle state.
- Proposal 2 (Sec 2.2): Study 6G DL WUS procedures in RRC connected state, taking into account: support of larger WUS capacity compared to 5G-A; single solution to avoid duplicated design/procedure; trade-off between latency and power saving gain; measurements by LR including RRM measurement.
- Proposal 3 (Sec 3.1.1): Study neighbour cell measurement performed by LR, considering the impact on the LR complexity to maintain acceptable measurement accuracy.
- Proposal 4 (Sec 3.1.2): Strive for unified synchronization signal for MR and LR, if feasible.
- Proposal 5 (Sec 3.2.2): RAN1 study DL WUS in RRC connected state to trigger per UE fast transition from low-power sub-state to data-transmission sub-state.
- Proposal 6 (Sec 3.2.2): RAN1 study DL WUS monitoring procedure for triggering PDCCH monitoring in 6G RRC connected state with the objective of supporting a single procedure.
- Proposal 7 (Sec 3.2.2): RAN1 study the possibility of using DL WUS to support functionalities other than wake-up, if beneficial, considering power impact from both network and device side, benefits of moving these functionalities from their legacy signal to 6G DL WUS, coverage performance, and number of bits needed to carry the functionality.
- Proposal 8 (Sec 5): Study 6G DL WUS with finer wakeup granularity (than 5G LP-WUS) in RRC idle state.
- Proposal 9 (Sec 5): Study 6G DL WUS procedures in RRC connected state taking into account: support of larger WUS capacity, compared to 5G-A; single solution to avoid duplicated design/procedure; trade-off between latency and power saving gain; measurements by LR, including RRM measurement.
- Proposal 10 (Sec 5): Study neighbour cell measurement performed by LR, considering the impact on the LR complexity to maintain acceptable measurement accuracy.
- Proposal 11 (Sec 5): Strive for unified synchronization signal for MR and LR, if feasible.
- Proposal 12 (Sec 5): If 6G DL WUS carries UE subgroup information, DL WUS triggers UE to monitor PO; if 6G DL WUS carries UE dedicated information, DL WUS triggers UE to perform RACH procedure.
- Proposal 16 (Sec 5): RAN1 study the possibility of using DL WUS to support functionalities other than wake-up, if beneficial, considering power impact both from network side and device side, benefits of moving these functionalities from their legacy signal to 6G DL WUS, coverage performance, and number of bits needed to carry the functionality.