Sidelink HARQ Feedback Channel Access via Backup Resource Switching
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Solution Overview
Problem
In wireless communication systems, particularly in sidelink communication, there is a challenge in efficiently accessing and transmitting sidelink Hybrid Automatic Repeat Request (HARQ) feedback due to failures in accessing initial feedback resources, leading to inefficiencies in data transmission and reception.
Innovation Solution
A method where a first User Equipment (UE) attempts to access a channel for sidelink HARQ feedback in a first feedback resource, which fails, and subsequently successfully accesses a second feedback resource within a predefined window, allowing for successful sidelink feedback transmission to a second UE, optimizing channel access and resource utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a first feedback resource is used for sidelink HARQ feedback transmission, then the feedback can be transmitted in the designated resource, but the channel access may fail due to resource contention or unavailability
Solution Approach 1:
The transmitting UE pre-configures multiple feedback resources (first feedback resource and second feedback resource) for the receiving UE before actual feedback transmission is needed. This preliminary preparation ensures that when the first feedback resource becomes unavailable, the receiving UE can immediately switch to the second feedback resource without delay, maintaining feedback transmission reliability while simplifying the channel access process.
Solution Approach 2:
The second feedback resource acts as an intermediary or backup channel when the primary first feedback resource fails. The transmitting UE provides indication information that mediates the switch between resources, allowing the receiving UE to transition from the failed first feedback resource to the alternative second feedback resource within the time window, thus resolving the channel access failure while maintaining feedback reliability.
2Reliability
If multiple feedback resources are provided as alternatives, then the feedback transmission reliability improves, but the resource management complexity increases
Solution Approach 1:
The feedback resources are segmented into a primary first feedback resource and a secondary second feedback resource, each with distinct functions. The first feedback resource is used for normal operations, while the second feedback resource is reserved as backup. This segmentation allows the system to manage complexity by clearly defining when and how to use each resource, rather than treating all feedback resources uniformly.
Solution Approach 2:
The feedback resource allocation is dynamic rather than static. The receiving UE monitors the availability of the first feedback resource and dynamically switches to the second feedback resource when needed, based on indication information from the transmitting UE. This dynamic approach allows the system to adapt to changing channel conditions and resource availability, maintaining reliability without permanently allocating complex resource structures.
3Productivity
If channel access is attempted in the first feedback resource, then the feedback can be transmitted immediately if successful, but time is lost when access fails and alternative resources must be used
Solution Approach 1:
The transmitting UE pre-configures the second feedback resource and provides indication information to the receiving UE in advance, before the actual feedback transmission attempt. This preliminary action ensures that when the first feedback resource access fails, the receiving UE already has the necessary information to immediately switch to the second feedback resource without any additional delay for resource selection or configuration, thus minimizing time loss while maintaining productivity.
Data Source
AI summary
In an example, a first User Equipment (UE) receives a sidelink transmission, associated with enabled sidelink Hybrid Automatic Repeat Request (HARQ) feedback, from a second UE in a first timing. The first UE attempts to access a channel for transmission of a sidelink HARQ feedback in a first feedback resource in a second timing. The sidelink HARQ feedback is in response to the sidelink transmission. The attempt to access the channel for the transmission of the sidelink HARQ feedback in the first feedback resource fails. The first UE performs channel access for a second feedback resource. The second feedback resource is within a window and/or within a predefined duration of the first timing or the second timing. In response to successfully performing the channel access, the first UE performs, in the second feedback resource, a sidelink feedback transmission of the sidelink HARQ feedback to the second UE.