R1-2508688
discussion
Discussion on energy efficiency for 6GR
From Xiaomi
Summary
Xiaomi presents 28 proposals and 4 observations covering energy efficiency for 6G Radio. The document addresses high-level principles, UE-side power saving (PDCCH monitoring reduction, scheduling, C-DRX, spectrum operations), network-side power saving (SSB, RACH, paging, Cell-DTX/DRX, spatial domain), joint UE-network energy saving mechanisms, and an evaluation framework including power models for both NW and UE.
Position
Xiaomi proposes that 6GR energy efficiency design must jointly consider network and UE gains from day one, avoiding the 5G pattern of separate timelines and late-stage specification. They propose PDCCH skipping, SSSG switching, and DCI carried by PDSCH as starting UE mechanisms, with further enhancements including PDCCH monitoring reduction within a search space and DRX timer optimization. For network-side saving, they propose extending default SSB periodicity with sparser synchronization raster and clustered sync signal provisioning, plus SSB adaptation limited to periodicities smaller than the default, while also pursuing L1-based paging adaptation and optimised Cell-DTX/DRX that reduces common channel transmission and retransmission-triggered extension. Joint mechanisms (BWP operation, Cell-DTX/DRX, C-DRX, multi-carrier operation) are proposed as starting points, with emphasis on reducing specific signalling for UE saving and incorporating UE requirements into NES decisions. For evaluation, they propose reusing 5G power states and a single BS category model, require a unified BW scaling method handling both down-scaling and up-scaling, and demand LR modelling that accommodates both shared and independent hardware architectures between LR and MR.
Key proposals
- Proposal 1 (Sec 2.1): Energy saving need to be jointly considered for network and UE; mechanisms need to be lean, native, universal and leverage 5G techniques while avoiding additional UE complexity/cost.
- Proposal 2 (Sec 2.2.1): PDCCH skipping, SSSG switching, and DCI carried by PDSCH should be considered as starting points for 6GR energy saving.
- Proposal 4 (Sec 2.2.2): BWP switching with potential simplification and cross-slot scheduling should be considered as starting points and further developed in 6GR.
- Proposal 5 (Sec 2.2.3): Enhanced DRX operation should be considered, at least regarding drx-InactivityTimer, drx-RetransmissionTimerDL, and drx-RetransmissionTimerUL.
- Proposal 6 (Sec 2.2.4): Study SCell dormancy with possible simplification, fast SCell activation, and multi-cell scheduling for UE power saving.
- Proposal 8 (Sec 2.2.6): UE assistance information for energy saving should be considered in 6GR.
- Proposal 10 (Sec 2.3.1): Sparser synchronization raster granularity should be considered with default SSB periodicity extension.
- Proposal 12 (Sec 2.3.1): SSB adaptation should be considered on top of default SSB periodicity extension, with adaptive SSB periodicity smaller than default.
- Proposal 14 (Sec 2.3.3): L1-based paging adaptation can be considered for 6GR NES.
- Proposal 15 (Sec 2.3.4): Cell DTX/DRX can be optimized to reduce common channel/signal transmission and reception.
- Proposal 17 (Sec 2.3.5): Dynamic adaptation of TRP on/off can be considered for 6GR energy saving, with UE behavior during TRP on/off transition to be considered.
- Proposal 19 (Sec 2.4): BWP operation, Cell-DTX/DRX, C-DRX, and multi-carrier operation can be considered as starting points for joint energy saving between network and UE.
- Proposal 21 (Sec 3.1.4): For joint NW-UE energy efficiency evaluation, report both NW and UE energy saving gains and performance impacts plus qualitative analysis on trade-offs and joint benefits/synergies.
- Proposal 24 (Sec 3.2.1): Reuse 5G power states (Deep sleep, Light sleep, Micro sleep, Active DL, Active UL) for 6G evaluation.
- Proposal 28 (Sec 3.2.2): RAN1 must ensure the LR functionality model accommodates shared or independent hardware between LR and MR.