NR V2X Sidelink DRX Timing from DCI Without PUCCH Configuration
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Solution Overview
Problem
In sidelink (SL) communication, there is a need to define clear time durations for user equipment (UE) to operate in active mode to receive sidelink grants efficiently, especially when discontinuous reception (DRX) configurations are used to conserve power, while ensuring reliable and low-latency communication.
Innovation Solution
A method and apparatus for a UE to start a hybrid automatic repeat request (HARQ) round trip time (RTT) timer based on downlink control information (DCI) after a physical uplink control channel (PUCCH) resource is not configured, allowing for efficient power saving and reliable SL communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If DRX configuration is used to save UE power, then power consumption is reduced, but the time duration for active mode operation becomes uncertain affecting communication reliability
Solution Approach 1:
The patent changes the parameter for HARQ RTT timer start timing from being based on SL grant reception to being based on PDCCH resource time domain. This parameter change provides clear timing definition for active mode operation, ensuring communication reliability while maintaining power saving benefits of DRX configuration.
2Reliability
If clear time duration definition is provided for active mode, then communication reliability is improved, but device complexity increases due to additional configuration parameters
Solution Approach 1:
The patent uses the existing PDCCH resource time domain parameter, which already serves for scheduling purposes, to also define the HARQ RTT timer start timing. This multi-functional use of an existing parameter avoids adding new configuration complexity while providing clear timing definition for reliable communication.
3Use of energy by moving object
If PUCCH resource is not configured, then power saving is maximized, but determining HARQ RTT timer start timing becomes ambiguous
Solution Approach 1:
The patent introduces the PDCCH resource time domain as an intermediary reference point to determine HARQ RTT timer start timing when PUCCH resource is not configured. This intermediary provides a clear and unambiguous timing reference, eliminating timing uncertainty while maintaining the power saving benefits of not configuring PUCCH resource.
Data Source
AI summary
Provided are a method by which a first apparatus communicates wirelessly, and an apparatus supporting same. The method comprises the steps of: obtaining a discontinuous reception (DRX) configuration containing information related to a hybrid automatic repeat request (HARQ) round trip time (RTT) timer; receiving, from a base station, downlink control information (DCI) including information related to at least one sidelink (SL) resource and information related to a physical uplink control channel (PUCCH) resource, on the basis of a physical downlink control channel (PDCCH) resource; and starting the HARQ RTT timer after the time domain of the PDCCH resource, on the basis that the PUCCH resource is not configured for the first apparatus, wherein the HARQ RTT timer may indicate the minimum duration before a retransmission grant is expected by the first apparatus.