Dynamic PSFCH Resource Allocation for NR V2X Groupcast HARQ Feedback
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Solution Overview
Problem
In groupcast communication, when the number of HARQ resources allocated to UEs in a group is less than the group size, efficient HARQ feedback is not possible, leading to suboptimal performance in V2X scenarios such as vehicle platooning and advanced driving, where reliable and low-latency communication is critical.
Innovation Solution
A method and apparatus for determining the number of physical sidelink feedback channel (PSFCH) resources related to a physical sidelink shared channel (PSSCH) resource and selecting a hybrid automatic repeat request (HARQ) feedback option based on the number of PSFCH resources and the group size, allowing efficient transmission of HARQ feedback information to other devices in the group.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the number of HARQ resources is increased to support larger groups, then the group size capacity is improved, but the resource allocation efficiency deteriorates when groups are small
Solution Approach 1:
The patent implements dynamic HARQ resource allocation where the number of PSFCH resources is adjusted based on the actual group size. When the group size is small, fewer PSFCH resources are allocated, improving resource efficiency. When the group size increases, more PSFCH resources are allocated to maintain feedback capability, thus resolving the contradiction between supporting large groups and maintaining resource efficiency for small groups.
2Reliability
If HARQ feedback is performed for all UEs in a large group, then the reliability is improved, but the feedback overhead increases beyond available resources
Solution Approach 1:
The patent segments the group of UEs into multiple subgroups, with each subgroup assigned to a different PSFCH resource for feedback transmission. This segmentation allows the system to handle large groups by distributing the feedback overhead across multiple resources, maintaining reliability while preventing feedback overload on any single resource.
3Productivity
If the number of PSFCH resources is reduced to improve resource efficiency, then the resource allocation efficiency is improved, but the HARQ feedback capability deteriorates for large groups
Solution Approach 1:
The system dynamically adjusts the number of PSFCH resources based on the detected group size. For small groups, fewer PSFCH resources are used to improve efficiency. For large groups, the system allocates more PSFCH resources to maintain feedback capability, thus resolving the contradiction between resource efficiency and feedback capability.
4Quantity of substance
If HARQ resources are allocated statically for maximum group size, then the maximum group capacity is improved, but the resource utilization deteriorates for smaller groups
Solution Approach 1:
The patent implements dynamic resource allocation where the number of PSFCH resources is determined based on the actual group size rather than being statically allocated for maximum capacity. This allows the system to optimize resource utilization for the current group size while maintaining the capability to support maximum group size when needed, resolving the contradiction between maximum capacity and utilization efficiency.
Data Source
AI summary
Provided are a method for performing, by a first device, group cast communication with one or more second devices in a group, and a device for supporting same. The method may comprise the steps of: determining the number of physical sidelink feedback channel (PSFCH) resources associated with a physical sidelink shared channel (PSSCH) resource; on the basis of the number of PSFCH resources and the size of the group, determining a hybrid automatic repeat request (HARQ) feedback option; and transmitting, to the one or more second devices, information associated with the HARQ feedback option. Here, the HARQ feedback option can be any one of a first HARQ feedback option or a second HARQ feedback option.