D2D Direct Link Release via RSRP Threshold and PC5 Signaling

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Solution Overview

Problem

In ProSe communication, there is a need to reduce unnecessary radio resource and power consumption, as well as inefficient operations in device-to-device (D2D) direct communication, particularly in releasing direct links, which leads to increased signaling and resource usage.

Innovation Solution

A method is introduced to optimize D2D direct communication by informing upper layers about the availability of radio resources, allowing for the autonomous release of direct links when the RSRP threshold is met, and exceptional PC5 signaling procedures to manage resource usage efficiently.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If a UE autonomously releases a direct link when RSRP threshold is met, then radio resource consumption is reduced, but communication reliability may deteriorate due to potential premature link release

Engineering Contradiction:
Improveradio resource consumptionVSAvoidcommunication reliability
Core Design Contradiction:
Loss of energyVSReliability

Solution Approach 1:

The patent implements feedback mechanisms where UEs exchange RSRP measurements and link status information through PC5 signaling. The releasing UE notifies the peer UE before link release, allowing the peer UE to prepare for link termination and maintain communication reliability while enabling resource release.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent applies preliminary action by having the releasing UE notify the peer UE in advance before actually releasing the direct link. This advance notification allows the peer UE to prepare for link termination, switch to alternative communication paths if needed, and maintain overall communication reliability while enabling efficient resource release.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If PC5 signaling is performed for direct link release, then communication reliability is improved through coordination, but signaling overhead and power consumption increase

Engineering Contradiction:
Improvecommunication reliabilityVSAvoidpower consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent applies partial action by implementing PC5 signaling only when necessary for direct link release, rather than continuous signaling. The signaling is triggered selectively based on RSRP threshold conditions, reducing overall power consumption while maintaining reliability when needed.

Inventive Principle:
Principle #16Partial or excessive action

Solution Approach 2:

The patent uses parameter changes by monitoring RSRP values and comparing them against thresholds to trigger signaling events. This parameter-based approach ensures signaling occurs only when link quality degrades sufficiently, optimizing the balance between reliability maintenance and power consumption reduction.

Inventive Principle:
Principle #35Parameter changes

3Use of energy by moving object

If direct link release procedures are simplified, then power consumption is reduced, but peer UE communication efficiency deteriorates due to lack of notification

Engineering Contradiction:
Improvepower consumptionVSAvoidpeer UE communication efficiency
Core Design Contradiction:
Use of energy by moving objectVSProductivity

Solution Approach 1:

The patent applies self-service by enabling UEs to autonomously determine when to release direct links based on locally measured RSRP values and configured thresholds. Each UE independently evaluates link quality and initiates release procedures when conditions are met, reducing the need for complex coordinated procedures while maintaining efficiency.

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP3379893B1Device-to-device direct communication method in wireless communication system and device therefor
Publication Date: 2021.02.17 LG ELECTRONICS INC
  • EP3379893B1 patent drawingFigure 1
  • EP3379893B1 patent drawingFigure 2
  • EP3379893B1 patent drawingFigure 3~4

AI summary

Disclosed are a method for performing direct communication and a remote UE, the method: receiving, at a Prose layer or an NAS layer of the remote UE, from a lower layer, information indicating that the use of a wireless resource for direct communication with relay UE is stopped since a predetermined AS condition is not satisfied; and stopping communication with the relay UE through a PC5 interface and locally releasing a direction connection with the relay UE.