R1-2601903
discussion
WUS operation in RRC states
From Ericsson
Summary
Ericsson presents 7 proposals and 7 observations on 6G WUS operation across RRC states, focusing on UE energy saving via a single WUS tool per state, full cell coverage for idle mode, and offloading RRM/RLM/BFD measurements to energy-efficient (EE) processing. They support studying EE processing measurement accuracy with preliminary results showing RSRP accuracy targets are achievable with 2Rx or smaller CFO values.
Position
Ericsson proposes studying a single 6G DL WUS tool for paging indication in Idle/Inactive state and a single WUS feature for PDCCH monitoring indication in Connected state, explicitly requiring the avoidance of overlapping functionalities like PEI and Rel-19 WUS. They argue entry/exit conditions for WUS monitoring are unnecessary in Idle/Inactive states because 6G WUS targets full cell coverage. They present a technical case for offloading serving cell RRM and RLM/BFD measurements, as well as neighboring cell RRM measurements, to EE processing state in RRC connected state, supported by energy saving evaluations showing full offloading provides 60%-90% gain. Their preliminary results indicate EE processing RSRP accuracy of 2dB using 3 SSBs with 160ms periodicity is achievable with 2Rx but may not be achieved with 1Rx under 5ppm CFO, requiring smaller CFO values for the 1Rx case.
Key proposals
- Proposal 1 (Sec 2.1): The 6GR WUS should be studied in all RRC states (like 5G WUS in Idle/Inactive, Connected states) to provide energy saving for devices in different use cases and scenarios.
- Proposal 2 (Sec 2.2.1): Study 6GR DL WUS waking up UE for paging PDCCH monitoring at least in RRC idle state, considering at least: UE energy saving gain, impact to latency, network overhead, network energy consumption, WUS indication granularity (at least UE-specific/UE-group level), WUS monitoring periodicity, WUS monitoring occasions, and other impacts.
- Proposal 3 (Sec 2.2.1): To avoid overlapping functionalities, design one single WUS tool for paging indication in Idle/Inactive state.
- Proposal 4 (Sec 2.3.1): Design only one option for 6G WUS monitoring in Connected state.
- Proposal 5 (Sec 2.3.1): To avoid overlapping functionalities, design one single WUS feature for PDCCH monitoring indication in Connected state.
- Proposal 6 (Sec 2.3.2): For RRC connected state, study serving cell RRM and RLM/BFD measurement based on 6GR measurement signal (e.g., at least 6GR sync signal) by EE processing, considering at least: UE energy saving gain, coverage and accuracy, and impact on the EE processing complexity.
- Proposal 7 (Sec 2.3.2): For RRC connected state, study neighboring cell RRM measurement based on 6GR measurement signal (e.g., at least 6GR sync signal) by EE processing, considering at least: UE energy saving gain, cell identification, cell number limitation, coverage and accuracy, impact on the EE processing complexity, and the power consumption of neighboring cell RRM measurement based on EE processing.
- Observation 1 (Sec 2.2.1): For 6G WUS operation in Idle/Inactive states, entry/exit conditions for WUS monitoring are not needed as WUS targets full cell coverage.
- Observation 2 (Sec 2.2.2): Based on preliminary results, with 2Rx and 5ppm CFO assumption, EE processing can achieve 2dB RSRP accuracy using 3 SSBs in a burst with 160ms SSB periodicity.
- Observation 3 (Sec 2.2.2): Based on preliminary results, with 1Rx and 5ppm CFO assumption, EE processing may not achieve 2dB RSRP accuracy using 3 SSBs in a burst with 160ms SSB periodicity. The accuracy might be improved by considering smaller CFO values.
- Observation 4 (Sec 2.2.3): With serving cell offloading, the energy saving gain drops dramatically when UE needs to perform neighboring cell measurement.
- Observation 5 (Sec 2.2.3): With full offloading, the energy saving gain is between 60%-90% except when the wake up rate is high and the long transition time/high energy [40000, 1600ms] model is applied.
- Observation 6 (Sec 2.2.3): With the long transition time/high transition energy model [40000, 1600ms), full offloading is necessary in order to have UE energy saving gain.
- Observation 7 (Sec 2.2.3): Deep sleep might provide more energy saving gain than ultra deep sleep when the wake up rate is high.