U2U Relay Discovery for Low-Latency Direct-to-Indirect Path Switching
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Solution Overview
Problem
In V2X systems, UEs communicating via sidelinks face issues when they move out of range or experience coverage problems, leading to prolonged path-switch latency and increased resource consumption during direct-to-indirect path switching.
Innovation Solution
A U2U relay UE-initiated mechanism for discovering and selecting a suitable relay UE to facilitate a direct-to-indirect path switch, utilizing distributed one-to-many broadcast and inter-UE coordination principles to proactively address sidelink coverage issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If traditional relay discovery mechanisms are used, then relay selection can be performed, but path-switch latency increases and resource consumption increases
Solution Approach 1:
The relay UE performs preliminary actions by proactively detecting sidelink coverage issues and announcing its availability before the source UE actually needs to switch paths. This advance preparation eliminates the need for extensive discovery processes during the critical path-switch moment, thereby reducing path-switch latency and improving relay discovery efficiency.
Solution Approach 2:
The mechanism implements feedback by having the relay UE send announcements to the destination UE about its availability and the detected coverage issues. This feedback loop allows the destination UE to be informed of relay availability proactively, enabling faster path-switch decisions and reducing the time required for relay discovery.
2Reliability
If extensive discovery processes are performed, then reliable relay selection can be achieved, but resource consumption increases
Solution Approach 1:
By performing relay availability detection and announcement as a preliminary action rather than during the critical selection phase, the system reduces the resource consumption required for reliable relay selection. The relay UE has already detected coverage issues and announced its availability, so the destination UE can make reliable selection decisions without triggering extensive discovery processes.
3Reliability
If direct communication is used, then communication simplicity is maintained, but service continuity is compromised when coverage issues occur
Solution Approach 1:
The relay UE acts as an intermediary that detects sidelink coverage issues and facilitates the transition from direct to indirect communication paths. By proactively announcing its availability and mediating the path-switch process, the relay UE ensures service continuity while managing the complexity of communication path changes.
Data Source
AI summary
A UE operates in a system where a source UE communicates using SL communications with a destination UE and detects a SL coverage issue with the sidelink communications between the source and destination UEs. The UE sends, to at least the destination UE, an announcement concerning at least one of the sidelink coverage issue or the UE being available as a relay UE candidate for an indirect path to the destination UE. The destination UE receives the announcement and communicates with the UE to set up and use the indirect path.