Sidelink Feedback Channel Configuration for V2X HARQ Retransmission
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Solution Overview
Problem
In V2X sidelink communication systems, there is a wastage of resources due to inefficient sidelink feedback transmission and retransmission, which affects the reliability and speed of hybrid automatic repeat request (HARQ) feedback.
Innovation Solution
The proposed method configures a sidelink feedback channel by transmitting sidelink control information (SCI) and transport blocks (TB) between terminals, using a NACK-based groupcast scheme, and identifies retransmission targets based on distance and direction information, allowing for efficient utilization of resources and quick HARQ feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional sidelink feedback transmission is used, then HARQ feedback can be transmitted between terminals, but resource waste occurs due to inefficient retransmission and feedback delivery
Solution Approach 1:
The patent segments the feedback channel resources by introducing zone IDs that divide the communication area into multiple zones. Each terminal is assigned to a specific zone, and feedback resources are allocated per zone rather than globally. This segmentation allows efficient resource utilization by limiting feedback transmission to relevant zones, reducing overall resource consumption while maintaining HARQ feedback reliability.
Solution Approach 2:
The patent applies preliminary action by pre-configuring zone IDs and feedback resource allocations before actual HARQ feedback transmission. The transmitting terminal determines the zone ID of the receiving terminal in advance, and feedback resources are pre-assigned based on these zone assignments. This preliminary configuration enables efficient resource utilization during actual feedback transmission without requiring dynamic resource allocation, thereby reducing resource waste.
2Reliability
If comprehensive retransmission to all terminals is performed, then HARQ feedback reliability is maintained, but resource consumption increases
Solution Approach 1:
The patent applies local quality by making retransmission behavior dependent on the specific zone and terminal location. Instead of uniform retransmission to all terminals, the transmitting terminal performs targeted retransmission only to terminals in zones where NACK feedback was received. This localized approach maintains HARQ reliability for affected terminals while improving overall resource utilization efficiency by avoiding unnecessary retransmissions to terminals that successfully received the original transmission.
Solution Approach 2:
The patent uses preliminary determination of zone IDs to enable selective retransmission. Before performing retransmission, the transmitting terminal has already determined which zones contain terminals that sent NACK feedback. This preliminary identification allows the system to perform retransmission only where necessary, balancing reliability requirements with resource efficiency.
3Loss of energy
If zone ID based feedback configuration is implemented, then resource waste is reduced, but system complexity increases
Solution Approach 1:
The patent applies universality by making the zone ID mechanism applicable to multiple functions: it serves as both a location identifier for terminals and a basis for feedback resource allocation. The same zone ID that identifies a terminal's location is also used to determine which feedback resources that terminal should monitor and use. This multi-functionality reduces the need for separate complex configuration mechanisms while achieving efficient resource utilization.
Solution Approach 2:
The patent reduces complexity through preliminary configuration of zone IDs and their associated feedback resources. Rather than requiring complex dynamic resource allocation algorithms, the system pre-establishes the mapping between zone IDs and feedback resources. This preliminary setup simplifies the operational complexity during actual HARQ feedback transmission, as terminals and the transmitting device can directly use the pre-configured mappings without complex real-time decisions.
Data Source
AI summary
A method of a first terminal may comprise: transmitting first SCI to a second terminal and a third terminal; transmitting a first TB to the second terminal and the third terminal based on scheduling by the first SCI; receiving a HARQ feedback including NACK information for the first TB through a first PSFCH resource; determining whether NACK information for at least one terminal among the second terminal and the third terminal has been received, based on the HARQ feedback; and in response to determining that the NACK information has been received, retransmitting the first TB to the at least one terminal.