Sidelink HARQ-ACK Prioritization in NR V2X
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Solution Overview
Problem
When physical uplink control channels (PUCCH) for sidelink (SL) hybrid automatic repeat request (HARQ)-ACK reports overlap with eMBB PUCCH, eMBB PUSCH, URLLC PUCCH, and URLLC PUSCH in time, user equipment (UE) needs to determine the appropriate channel for transmission.
Innovation Solution
The UE receives information related to a first PUCCH for a SL HARQ-ACK report from a base station, transmits sidelink control channels (SCI) for scheduling a physical sidelink shared channel (PSSCH), and generates the SL HARQ-ACK report. The UE performs prioritization procedures between overlapping PUCCHs based on priority indices and selects a PUSCH to resolve overlapping issues, ultimately transmitting the SL HARQ-ACK report through the selected PUSCH.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE transmits multiple PUCCH channels simultaneously for SL HARQ-ACK report and eMBB/URLLC uplink control, then the reliability of control information transmission is improved, but the device complexity and resource conflict increase
Solution Approach 1:
The patent applies parameter changes by introducing priority indices (0 or 1) to differentiate between eMBB and URLLC PUCCH channels. The UE determines which channel to transmit based on comparing these priority parameters, allowing systematic resolution of resource conflicts without complex decision logic. This parameter-based prioritization mechanism resolves the contradiction by providing a simple, rule-based approach to channel selection.
2Object-generated harmful factors
If the UE resolves overlapping PUCCH channels by prioritization, then the resource conflict is reduced, but the transmission timing and latency may increase
Solution Approach 1:
The patent implements preliminary action by having the UE determine the priority indices of overlapping PUCCH channels in advance, before the actual transmission conflict occurs. The UE identifies the higher-priority channel (URLLC with index 0 or eMBB with index 1) and pre-determines which channel will carry the SL HARQ-ACK report. This advance determination eliminates transmission delays that would result from real-time conflict resolution.
3Object-generated harmful factors
If the UE multiplexes SL HARQ-ACK report onto PUSCH instead of using dedicated PUCCH, then the channel overlap is resolved, but the control information may be lost or delayed
Solution Approach 1:
The patent uses the PUSCH channel as an intermediary carrier for SL HARQ-ACK reports when dedicated PUCCH resources are unavailable or overlap with higher-priority channels. Instead of losing control information, the UE multiplexes the SL HARQ-ACK report onto the PUSCH data channel, which has already been scheduled and confirmed as available. This intermediary approach ensures reliable delivery of control information without requiring separate dedicated PUCCH resources.
Data Source
AI summary
Provided are a method for performing wireless communication by a first device and an apparatus supporting same. The method may comprise: receiving, from a base station, information related to a first physical uplink control channel (PUCCH) for a sidelink (SL) hybrid automatic repeat request (HARQ)-acknowledgment (ACK) report; transmitting, to a second device through a physical sidelink control channel (PSCCH), a first sidelink control channel (SCI) for scheduling of a physical sidelink shared channel (PSSCH) and a second SCI; transmitting, to the second device through the PSSCH, the second SCI and data; generating the SL HARQ-ACK report for the data.