NR-V2X HARQ Response Timing Alignment Across Sidelink and Uplink
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Solution Overview
Problem
In direct communication between terminals in NR-V2X, there is a timing discrepancy between the base station and the terminal for transmitting sidelink Hybrid Automatic Repeat Request (HARQ) responses when the sidelink synchronization source is not the base station.
Innovation Solution
The timing of HARQ response transmission is adjusted by aligning the UL feedback timing with the PSFCH timing based on an offset indicated by the base station, ensuring synchronized transmission and reception between the terminal and the base station.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the sidelink synchronization source is not the base station, then direct communication between terminals can be established, but timing discrepancy occurs between base station and terminal for HARQ response transmission
Solution Approach 1:
The base station pre-configures offset information (k1, k2) to the terminal before HARQ response transmission. This preliminary configuration allows the terminal to calculate the correct PUCCH transmission timing in advance, eliminating timing discrepancies that would otherwise occur when the sidelink synchronization source is not the base station.
Solution Approach 2:
The offset information (k1, k2) acts as an intermediary parameter that mediates between the sidelink timing (PSFCH) and uplink timing (PUCCH). By introducing this intermediate timing offset, the system reconciles the timing difference caused by using a non-base-station synchronization source, enabling accurate HARQ response transmission.
2Ease of operation
If HARQ response timing is determined without offset adjustment, then transmission simplicity is maintained, but timing ambiguity occurs between base station and terminal
Solution Approach 1:
The system changes the timing parameter by introducing offset values (k1, k2) that adjust the PUCCH transmission timing relative to the PSFCH timing. This parameter adjustment resolves the timing ambiguity while maintaining the overall simplicity of the HARQ mechanism, as the offset is simply added to the timing calculation.
3Device complexity
If PUCCH timing is aligned with PSFCH timing without offset, then transmission timing is straightforward, but timing mismatch occurs when synchronization source differs from base station
Solution Approach 1:
The offset information serves as a timing intermediary that bridges the gap between PSFCH and PUCCH timing when their direct alignment would be incorrect. Instead of changing the fundamental timing relationship, the offset acts as a corrective intermediary that adjusts the PUCCH timing to match the base station's expected reception time.
Data Source
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AI summary
A terminal includes a reception unit configured to receive, from another terminal, a retransmission control related response via a first channel used for transmission and reception of the retransmission control related response, and receive, from a base station, information indicating a first offset in a time domain from the first channel to a second channel for transmitting the retransmission control related response to the base station; a control unit configured to assume a timing of the first channel, and determine a timing of the second channel based on the assumed timing of the first channel and the first offset; and a transmission unit configured to transmit the retransmission control related response to the base station via the second channel.