Sidelink DAI Counting for Unambiguous HARQ Feedback
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Solution Overview
Problem
The existing LTE V2X systems face challenges in efficiently managing HARQ feedback on sidelinks due to the lack of a specialized Downlink Assignment Index (DAI) design, leading to inconsistencies in understanding between communication parties, particularly in NR V2X Mode 2, where channel sensing impacts PSFCH channels.
Innovation Solution
A method is introduced to design different counting methods for DAIs in sidelink communication, distinguishing between first-type and second-type signalings, where the first-type signaling counts only groupcast transmissions and the second-type signaling counts both groupcast and unicast transmissions, allowing for improved HARQ feedback efficiency and avoiding ambiguity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a unified DAI counting method is used for both groupcast and unicast signalings, then the system complexity is reduced, but ambiguity arises in HARQ feedback interpretation between communication parties
Solution Approach 1:
The patent segments the DAI counting method by signaling type. First-type signalings (groupcast) use a first counting method where the first field value relates only to the number of first-type signalings. Second-type signalings (unicast) use a second counting method where the first field value relates to both first-type and second-type signalings. This segmentation eliminates ambiguity in HARQ feedback interpretation while maintaining manageable system complexity through clear, type-specific rules.
2Reliability
If different counting methods are designed for first-type and second-type signalings, then HARQ feedback reliability is improved, but the device complexity increases
Solution Approach 1:
The patent applies local quality by making the DAI counting behavior dependent on the local property of signaling type. Each signaling type (first-type or second-type) has its own tailored counting method appropriate to its characteristics. The receiving node determines which counting method to apply based on the local identification of signaling type, achieving high HARQ feedback reliability without requiring complex global coordination.
3Productivity
If channel sensing is performed in NR V2X Mode 2, then resource selection efficiency is improved, but interference to PSFCH channels occurs
Solution Approach 1:
The patent extracts the HARQ feedback indication from the general channel sensing process. By using the first field in the first signaling to explicitly indicate HARQ feedback information, the system separates feedback transmission from data transmission resources. This extraction allows channel sensing to proceed efficiently for resource selection while preventing interference to dedicated PSFCH channels, as the feedback is carried in the control signaling itself.
Data Source
AI summary
The disclosure provides a method and a device in a node used for wireless communication. A first node monitors a first-type signaling and a second-type signaling in a first time-frequency resource pool and a second time-frequency resource pool respectively, receives a first signaling, and transmits a first information block. The first signaling is used for determining the first information block; the first signaling includes a first field; when the first signaling is the first-type signaling, a value of the first field is related to a number of the first-type signalings transmitted in the first time-frequency resource pool, and is unrelated to a number of the second-type signalings transmitted in the second time-frequency resource pool. The above method improves the efficiency of HARQ feedback in sidelink transmission.