DRX HARQ RTT Timer Configuration for NR V2X Sidelink
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Solution Overview
Problem
The existing wireless communication systems lack clear definitions for the start time and duration of Uu DRX HARQ RTT TimerSL and Uu DRX Retransmission TimerSL when UL resources, such as PUCCH and PUSCH resources, are not configured, leading to potential delays and inefficiencies in sidelink communication.
Innovation Solution
A method where a UE obtains a DRX configuration including information related to a HARQ RTT timer, with a value of 0 for the HARQ RTT timer when the PUCCH configuration and PSFCH resource are not configured in the sidelink resource pool, allowing for efficient sidelink communication by defining the minimum duration before an SL retransmission grant is expected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If UL resources (PUCCH, PUSCH) are not configured for SL HARQ feedback, then device complexity is reduced, but the start time and duration of DRX timers become undefined causing communication delays
Solution Approach 1:
The patent applies parameter changes by setting the HARQ RTT timer value to 0 when PUCCH configuration and PSFCH resources are not configured. This parameter change resolves the timing uncertainty by establishing a clear default behavior, allowing the UE to immediately start the retransmission timer without waiting for an undefined HARQ feedback timing period.
2Use of energy by moving object
If DRX operation is implemented in NR V2X, then energy saving is improved, but timer definition clarity deteriorates when UL resources are not configured
Solution Approach 1:
The patent sets the HARQ RTT timer value to 0 under specific conditions (when PUCCH configuration and PSFCH resources are not configured), which ensures reliable timer operation. This parameter change eliminates ambiguity in timer startup and duration, ensuring that DRX operation functions reliably without requiring complex UL resource configurations.
Solution Approach 2:
The patent enables the UE to autonomously determine timer behavior based on its own configuration state. When UL resources are not configured, the UE automatically uses a HARQ RTT timer value of 0, allowing it to self-manage the DRX timing without network intervention or complex external references.
3Reliability
If HARQ RTT timer value is set to 0 when PUCCH and PSFCH are not configured, then timer operation reliability is improved, but the minimum duration for retransmission expectation is reduced
Solution Approach 1:
The patent changes the HARQ RTT timer value parameter based on configuration status. When PUCCH and PSFCH are not configured, the timer value is set to 0, which reflects the actual operational reality that the UE can immediately expect retransmission grants without waiting for traditional HARQ feedback timing periods.
Data Source
AI summary
Proposed are a method by which a first device performs wireless communication, and an apparatus supporting same. For example, the first device may obtain a DRX configuration including information related to a HARQ RTT timer. For example, the first device may obtain information related to a sidelink (SL) resource pool. For example, the first device may start the HARQ RTT timer. For example, the HARQ RTT timer may be a minimum duration before an SL retransmission grant is expected by the first device. For example, based on (i) a physical uplink control channel (PUCCH) configuration not being configured, and (ii) a physical sidelink feedback channel (PSFCH) resource not being configured in the SL resource pool, a value of the HARQ RTT timer may be 0.