UE-to-UE Relay Selection Using PC5 Measurements and Target Feedback
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Solution Overview
Problem
The challenge in wireless communication systems is the efficient selection and reselection of a relay UE based on measurements in UE-to-UE relay operations, particularly in scenarios requiring high reliability and low latency.
Innovation Solution
A method and apparatus for a source remote UE to establish a PC5 link with a first relay UE, perform measurements on candidate relay UEs, transmit ID information to a target remote UE, receive measurement results, and select a second relay UE based on these measurements, utilizing sidelink discovery reference signal received power (SD RSRP) thresholds and prioritization strategies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If relay UE selection is performed based on SD RSRP measurements, then reliability of relay connection is improved, but measurement and selection complexity increases
Solution Approach 1:
The source remote UE performs measurements on candidate relay UEs and obtains measurement results before actual relay selection. This preliminary measurement action allows the system to evaluate multiple candidates in advance, ensuring reliable connection selection while managing complexity through structured pre-assessment procedures.
Solution Approach 2:
The target remote UE provides feedback information about its preferred relay UE based on its own measurements. This feedback mechanism enables both source and target UEs to contribute to the relay selection decision, improving connection reliability through mutual agreement while distributing the measurement burden to reduce overall system complexity.
2Measurement precision
If multiple candidate relay UEs are measured and evaluated, then relay selection accuracy is improved, but time consumption for relay selection increases
Solution Approach 1:
The system measures and evaluates multiple candidate relay UEs beyond the minimum single candidate, performing partial measurements on all detected candidates rather than exhaustive detailed measurements. This approach improves selection accuracy by considering multiple options while controlling time consumption through selective measurement depth.
Solution Approach 2:
Measurement of candidate relay UEs is performed in advance before final relay selection is made. This preliminary measurement phase allows the system to gather necessary data about multiple candidates efficiently, improving selection accuracy while separating the measurement time from the decision time.
3Reliability
If SD RSRP threshold filtering is applied to candidate relay UEs, then connection quality is improved, but number of available relay options decreases
Solution Approach 1:
The SD RSRP threshold filtering is applied locally to each candidate relay UE based on its specific measurement results. This allows the system to maintain high connection quality by filtering out inadequate candidates while preserving adaptability by keeping multiple qualified candidates that meet the threshold, rather than applying a uniform restrictive filter.
Data Source
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AI summary
An embodiment provides an operation method of a source remote UE related to relay selection in a user equipment (UE)-to-UE relay in a wireless communication system, the method comprising the steps in which: the source remote UE establishes a PC5 link with a first relay UE; the source remote UE establishes an end-to-end link with a target remote UE via the first relay UE; the source remote UE performs measurement for multiple candidate relay UEs; the source remote UE transmits, to the target remote UE, ID information of at least one candidate relay UE among the multiple candidate relay UEs; the source remote UE receives, from the target remote UE, the result of measurement, by the target remote UE, for the at least one candidate relay UE; and the source remote UE selects a second relay UE on the basis of the result of the measurement.