Sidelink UE Assistance Patterns for Half-Duplex Collision Avoidance
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Solution Overview
Problem
The half-duplex issue in sidelink communication between user equipments (UEs) leads to reliability degradation and latency issues in unicast and multicast scenarios due to simultaneous transmission and reception limitations, particularly in 5G vehicle-to-everything (V2X) mode2 operations.
Innovation Solution
UEs exchange SL UE assistance information, including pattern information such as transmission periodicity, time intervals, and resource mapping types, to coordinate resource usage and avoid collisions, using RRC messages or MAC CEs for communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If UE operates in mode2 and selects resources autonomously based on channel monitoring, then device complexity and base station overhead are reduced, but communication reliability deteriorates due to half-duplex collisions between transmission and reception
Solution Approach 1:
The receiving UE performs preliminary action by transmitting SL UE assistance information about its reception patterns before the transmitting UE selects resources. This allows the transmitting UE to anticipate and avoid half-duplex collisions by knowing in advance which time-domain resources the receiving UE will be occupied with for reception, thereby resolving the reliability issue while maintaining mode2 autonomous operation
Solution Approach 2:
The receiving UE provides feedback in the form of SL UE assistance information that indicates its reception patterns and time-domain resource usage. This feedback mechanism enables the transmitting UE to make informed resource selection decisions that avoid collisions, improving communication reliability without requiring base station intervention
2Reliability
If retransmission is performed to handle failed receptions, then communication reliability is improved, but latency increases and cannot meet service requirements
Solution Approach 1:
By performing preliminary resource coordination through SL UE assistance information exchange, the system prevents collisions before they occur, eliminating the need for retransmissions. This ensures both high communication reliability and low latency by avoiding the time loss associated with retry mechanisms
3Productivity
If UE uses the same time-domain resource for both transmission and reception, then resource utilization efficiency is improved, but communication reliability deteriorates due to half-duplex limitations
Solution Approach 1:
The receiving UE provides feedback through SL UE assistance information that reveals its reception schedule and time-domain resource usage. This enables the transmitting UE to adjust its transmission resource selection to avoid overlapping with reception activities, maintaining resource utilization efficiency while ensuring reliable communication by preventing half-duplex conflicts
Data Source
AI summary
An information transmission method includes: receiving, by first UE, Sidelink UE assistance information transmitted by second UE, wherein the Sidelink UE assistance information includes at least one piece of pattern information; determining, by the first UE according to the Sidelink UE assistance information, a resource occupied by transmission between the first UE and the second UE.