R1-2509353
discussion
Views on Energy Efficiency
From CEWiT
Summary
This CEWiT contribution proposes 8 observations/proposals for 6G energy efficiency enhancements, covering DL common signal adaptations, PRACH spatial domain optimization, enhanced DTX/DRX, spatial/power domain adaptations, blind decoding reduction, and UE BWP adaptation.
Position
CEWiT proposes supporting three specific DL common signal enhancements for longer synch signal periodicity: synch signal repetitions within one periodic instance as a burst set with small internal period, On-Demand SSB and On-Demand SIB1 triggered between consecutive always-on synch signals for premium UEs requiring faster access, and Simplified SSB (e.g., only PSS) transmitted with 20 ms periodicity as a lighter DL signal for cell identification. They argue for extending PRACH spatial domain adaptation beyond 5G Release 19 time-domain mechanisms to support non-uniform RACH resource assignment across beams or regions based on spatial traffic patterns. They present technical analysis that BS-autonomous spatial adaptation without prior CSI reporting (using channel prediction or prior knowledge) yields additional 13.92% and 8.7% energy savings in low and medium loads versus adaptation with CSI reporting, and they propose studying an optimal CSI framework that extends spatial/power adaptation to cell-specific signals like SSB and enables multi-TRP and AI/ML-based adaptations.
Key proposals
- Proposal 1 (Sec 2.1/2.3/2.4): 6G should support synch signal repetitions within one instance of longer periodicity, On-Demand Signals for initial access including OD-SSB & OD-SIB1 in between consecutive always on synch signals, and Simplified SSB with 20 ms periodicity.
- Proposal 2 (Sec 3): PRACH adaptations in spatial domain should be considered for a practical network deployment, at least supporting non uniform assigning of RACH resources across different regions.
- Proposal 3 (Sec 4): Study enhanced Cell DTX/DRX with 5G Cell DTX/DRX as baseline, considering applicability to IDLE/INACTIVE and CONNECTED state, turning off common signals/channels during non-active duration, flexible DTX/DRX pattern including adaptation based on UAI, joint design of Cell DTX/DRX and UE DRX, and utilizing AI/ML for DTX/DRX adaptations.
- Proposal 4 (Sec 5): Spatial and power domain adaptations should be supported in 6G for network energy savings, with areas for enhancements considering optimal CSI framework and reporting, application to both UE specific and cell specific signals e.g. SSB, multi-TRP adaptations, enhancements based on AI/ML, and co-ordination with longer synch signal period based on traffic.
- Proposal 5 (Sec 6): Study mechanism for reducing blind decoding attempts at UE including dynamic indication of blind decoding info (search space set, CORESET, DCI format, PDCCH occasion count etc), and mechanisms to provide blind decoding information before PDCCH monitoring occasions.
- Proposal 6 (Sec 7): Study and evaluate enhanced BW adaptation mechanism for 6G EE improvement, considering adaptation of bandwidth-dependent parameters, faster adaptation without BWP switching/shorter data interruption by restricting parameter set, L1-triggered adaptation with improved reliability, and cell/group-wise indication for network energy saving use case.
- Observation 1 (Sec 2): Energy efficiency enhancements for DL common signals provide significant energy savings: On-Demand SIB1 provides 36.2%, 28.2%, and 20.4% saving in low, light, and medium loads respectively; Simplified SSB provides 23.3%, 14.2%, and 9.82% saving under same conditions.
- Observation 2 (Sec 5): Spatial domain adaptation independently by the BS without prior CSI reporting provides an extra energy saving of 13.92% and 8.7% in low and medium loads respectively when compared to spatial adaptation with CSI reporting.