NR V2X DRX Timer Start Logic for Sidelink Resource Retention

Solution Overview

Problem

The existing technologies face challenges in managing and optimizing the UE's transition from a sleep state due to the expiration of the legacy Uu DRX inactivity timer, which can lead to the loss of communication resources, especially in the case of UE's transitioning to a sleep state without receiving additional SL retransmission resources from the base station.

Innovation Solution

The introduction of a new Uu inactivity timer mechanism that allows the UE to efficiently receive information related to additional SL resources, ensuring continuous communication by preventing the UE from entering a sleep state prematurely.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the UE uses the legacy Uu DRX inactivity timer to manage sleep state transition, then energy saving is improved, but the UE may miss additional SL retransmission resources allocated by the base station

Engineering Contradiction:

Improveenergy savingVSAvoidcommunication reliability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent segments the DRX inactivity timer into two separate timers: the legacy Uu DRX inactivity timer for general Uu communication and the new SL DRX inactivity timer specifically for sidelink communication. This segmentation allows each timer to independently manage its own timeout behavior, enabling the UE to remain awake for additional SL resources while still benefiting from energy saving through the legacy timer for other communications.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces a new SL DRX inactivity timer as an intermediary mechanism between the base station and the UE for managing sidelink communication state. This intermediary timer specifically tracks sidelink retransmission opportunities, acting as a mediator that prevents the UE from transitioning to sleep state during critical SL communication periods without interfering with the legacy Uu DRX mechanism.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Loss of energy

If the UE transitions to sleep state after legacy Uu DRX inactivity timer expiration, then power consumption is reduced, but additional SL resources allocated by base station are lost

Engineering Contradiction:

Improvepower consumptionVSAvoidcommunication resources

Core Design Contradiction:

Loss of energyVSLoss of substance

Solution Approach 1:

The patent segments the DRX inactivity timer into two separate timers: the legacy Uu DRX inactivity timer for general Uu communication and the new SL DRX inactivity timer specifically for sidelink communication. This segmentation allows each timer to independently manage its own timeout behavior, enabling the UE to remain awake for additional SL resources while still benefiting from energy saving through the legacy timer for other communications.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements preliminary action by introducing a new SL DRX inactivity timer that starts counting down when the base station allocates SL resources through DCI. This preliminary timer setup ensures the UE remains awake in advance for potential additional SL retransmission opportunities before the legacy Uu DRX inactivity timer would cause it to sleep, preventing resource loss while maintaining power efficiency.

Inventive Principle:

Principle #10Preliminary action

3Adaptability or versatility

If the base station allocates additional SL retransmission resources without receiving PUCCH from UE, then communication flexibility is improved, but the UE cannot receive resource information if in sleep state

Engineering Contradiction:

Improvecommunication flexibilityVSAvoidresource allocation information

Core Design Contradiction:

Adaptability or versatilityVSLoss of information

Solution Approach 1:

The patent segments the DRX inactivity timer into two separate timers: the legacy Uu DRX inactivity timer for general Uu communication and the new SL DRX inactivity timer specifically for sidelink communication. This segmentation allows each timer to independently manage its own timeout behavior, enabling the UE to remain awake for additional SL resources while still benefiting from energy saving through the legacy timer for other communications.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements feedback through the new SL DRX inactivity timer that provides timing information about when the UE should expect additional SL resource allocations. This feedback mechanism allows the base station to allocate resources flexibly while ensuring the UE is awake and ready to receive the allocation information at the appropriate time, resolving the information loss problem.

Inventive Principle:

Principle #23Feedback

Data Source

PatentEP4236557B1Method and device for starting timer for activation time in NR v2x

Publication Date: 2025.12.24 LG ELECTRONICS INC

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Figure 2(a)~2(d)
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AI summary

Provided is a method for a first device to perform wireless communication, and a device supporting same. The method may comprise the steps of receiving, from a base station, a discontinuous reception (DRX) configuration including information related to a DRX cycle and information related to a timer for an active time; receiving, from the base station, downlink control information (DCI) including information related to one or more sidelink (SL) resources and information related to a physical uplink control channel (PUCCH) resource; and starting the timer for the active time after the final SL resource among the one or more SL resources scheduled by the DCI, wherein the timer is started on the basis that the PUCCH resource is not configured for the first device.