Multi-TRP Sidelink Congestion Control Using Per-TRP CR Evaluation
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Solution Overview
Problem
Congestion control mechanisms for user equipment (UE) with multiple transmit-receive points (TRPs) are sub-optimal as they rely on reporting the largest received signal strength indicator (RSSI), which may not accurately reflect individual TRP conditions, limiting resource usage, modulation and coding scheme, and maximum transmit power.
Innovation Solution
The UE evaluates a channel occupancy ratio (CR) for each TRP and determines whether to transmit on one or more TRPs based on the evaluated CR and CR limits, allowing for optimized resource allocation and transmission decisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the UE reports the largest RSSI measured among multiple TRPs, then the congestion control mechanism can be implemented with a single threshold, but the reported RSSI does not accurately reflect the channel conditions of each individual TRP, leading to sub-optimal resource allocation
Solution Approach 1:
The patent divides the congestion control mechanism into per-TRP segments. Instead of reporting a single aggregated RSSI value, the UE now evaluates and reports channel occupancy ratio separately for each TRP. This segmentation allows the network to make transmission decisions based on the specific channel conditions of each TRP, resolving the contradiction between simplified control and accurate measurement.
2Ease of operation
If the congestion control is based on the largest RSSI reported by the UE, then the control mechanism is simplified, but the resource usage, modulation and coding scheme, and maximum transmit power are limited for mTRP UEs
Solution Approach 1:
The patent introduces dynamic per-TRP channel occupancy ratio evaluation. The UE dynamically assesses the channel occupancy for each TRP individually and reports these separate measurements. This dynamic approach enables the network to adapt transmission parameters such as resource allocation, modulation and coding scheme, and maximum transmit power based on the specific conditions of each TRP, thereby improving resource usage efficiency while maintaining operational simplicity.
Data Source
AI summary
Aspects presented herein improve congestion control mechanism for UEs with multiple TRPs, where at least one of the SL RSSI measurement, the CBR measurement, the CR evaluation and/or the congestion control mechanism for the UE is optimized. In one aspect, the apparatus evaluates a CR for each TRP of a plurality of TRPs at the UE. The apparatus determines whether the UE is allowed to transmit on one or more of the TRPs of the plurality of TRPs based at least on the evaluated CR for each TRP of the plurality of TRPs and on at least one CR limit. The apparatus transmits on at least one TRP of the one or more of the TRPs based on the determination whether to transmit on the one or more TRPs.