Multi-Symbol PSFCH Resources for Reliable Sidelink HARQ Feedback
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Solution Overview
Problem
Existing wireless communication systems face challenges in maintaining reliable and efficient hybrid automatic repeat request (HARQ) acknowledgement (ACK) feedback for sidelink transmissions, particularly in scenarios requiring ultra-reliable low latency communications (URLLC), due to limitations in the duration of physical sidelink feedback channel (PSFCH) resources.
Innovation Solution
The implementation of PSFCH resources comprising more than two symbols, with a portion dedicated to automatic gain control (AGC) training and another portion for HARQ-ACK feedback, enhances the reliability of HARQ-ACK transmission by increasing the number of symbols available for feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PSFCH resource duration is limited to two symbols, then resource allocation is efficient and simple, but HARQ-ACK feedback reliability is insufficient for URLLC requirements
Solution Approach 1:
The PSFCH resource is segmented into multiple symbols (more than two) to provide sufficient time for reliable HARQ-ACK feedback transmission. This segmentation allows the system to meet URLLC reliability requirements by extending the feedback duration while maintaining structured resource allocation through separate AGC and feedback symbol portions.
2Reliability
If PSFCH resource duration is extended to more than two symbols, then HARQ-ACK feedback reliability improves, but resource allocation complexity increases
Solution Approach 1:
The AGC training is performed in advance within the PSFCH resource structure (using initial symbols) before the actual HARQ-ACK feedback transmission. This preliminary action allows the receiving device to establish proper gain control beforehand, ensuring that the subsequent feedback symbols can be reliably decoded without extending the critical feedback path.
3Reliability
If PSFCH resource duration is increased, then feedback reliability improves, but the number of available resources for other transmissions decreases
Solution Approach 1:
The PSFCH resource structure is designed with local quality differentiation, where specific symbols are dedicated to AGC training and others to HARQ-ACK feedback. This localized functional assignment optimizes each portion for its specific purpose while maintaining overall resource efficiency, allowing reliable feedback without excessively reducing resources available for other sidelink transmissions.
Data Source
AI summary
Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a first user equipment (UE) may receive, from a second UE or a network node, a configuration for a resource pool, wherein the resource pool is associated with a physical sidelink feedback channel (PSFCH) resource comprising more than two symbols. The first UE may receive, from the second UE, a sidelink transmission. The first UE may transmit, to the second UE and based at least in part on the sidelink transmission, a hybrid automatic repeat request (HARQ) acknowledgement (ACK) feedback based at least in part on the PSFCH resource comprising more than two symbols. Numerous other aspects are described.