Sidelink Sync Signal Evaluation Period Adjustment for LBT Failures
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Solution Overview
Problem
In wireless communication systems, particularly in 5G networks, the reuse of traditional NR sidelink and NR-U channel structures for sidelink unlicensed operation faces challenges due to unpredictable Listen Before Talk (LBT) failures, leading to incorrect initiation, reselection, and measurement of synchronization signals, which affect the reliability of sidelink communications.
Innovation Solution
A terminal device measures the reference signal receiving power associated with a physical sidelink broadcast channel (PSBCH) and determines the number of consecutive periods with LBT failures to extend the evaluation, detection, or measurement periods, allowing for a more reliable evaluation of the reference signal power, thereby improving the accuracy of sidelink synchronization signal availability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If traditional NR sidelink and NR-U channel structures are reused for sidelink unlicensed operation, then device complexity is reduced, but reliability deteriorates due to unpredictable LBT failures causing incorrect signal initiation and reselection
Solution Approach 1:
The patent introduces dynamic adjustment mechanisms for evaluation periods, detection periods, and measurement periods based on LBT failure conditions. The terminal device adapts these time parameters dynamically when LBT failures are detected, allowing the system to maintain reliability without changing the fundamental channel structure. This dynamic adaptation resolves the contradiction by keeping the channel structure simple while adjusting operational parameters to compensate for LBT failures.
2Reliability
If evaluation period is extended to account for LBT failures, then reliability improves, but time consumption increases
Solution Approach 1:
The evaluation period is made dynamic rather than fixed. The terminal device adjusts the evaluation period length based on whether LBT failures are detected. When LBT failures occur, the evaluation period is extended to allow sufficient time for accurate assessment. When no LBT failures occur, the evaluation period remains at its standard shorter duration. This dynamic approach resolves the contradiction by only increasing time consumption when actually needed for reliability.
Solution Approach 2:
The patent changes the time parameter (evaluation period duration) based on the operational condition (LBT failure status). By adjusting this parameter dynamically, the system achieves high reliability during problematic conditions while maintaining efficient operation during normal conditions, thus resolving the trade-off between reliability and time consumption.
3Measurement precision
If detection period with allowed dropping rate is adjusted based on consecutive LBT failure periods, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent implements a feedback mechanism where the terminal device monitors LBT failure occurrences and uses this information to adjust the detection period and measurement period. The feedback loop counts consecutive periods with LBT failures and adjusts the allowed dropping rate accordingly. This feedback-based approach improves measurement precision by adapting to actual channel conditions while keeping the implementation relatively simple through systematic counting and threshold-based adjustments.
Data Source
AI summary
Embodiments of the present disclosure relate to at least one evaluation period, a detection period with allowed dropping rate or a measurement period determination. A terminal device measures a reference signal receives power (RSRP) associated with a physical sidelink broadcast channel (PSBCH) of a synchronization reference device, determines a number of consecutive periods associated with a listen before talk (LBT) failure in which a sidelink synchronization signal (SLSS) is unavailable from the synchronization reference device, and determines, based on the number of consecutive periods, at least one of an evaluation period, a detection period with allowed dropping rate or a measurement period for evaluating the RSRP, wherein the consecutive periods correspond to a plurality of consecutive sidelink synchronization signal block (S-SSB) periods or a plurality of consecutive discontinuous reception (DRX) cycles. Thus, wrong initiation of SLSS transmission event and wrong reselection of a SyncRef UE may be avoided.