PC5-RRC Link Failure Detection Using Sidelink DTX Thresholds

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Solution Overview

Problem

Existing wireless communication systems face challenges in effectively managing radio link failures (RLF) in PC5-RRC connections, particularly in detecting radio link failures through discontinuous transmissions (DTXs) for sidelink communication.

Innovation Solution

A method and device for establishing a PC5-RRC connection, monitoring discontinuous transmissions (DTXs) for radio link failure (RLF) detection, and detecting RLF when the maximum number of DTXs is reached, based on the absence of physical sidelink feedback channel (PSFCH) reception on a PSFCH occasion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If DTX monitoring is implemented for RLF detection in PC5-RRC connections, then communication reliability is improved, but device complexity increases due to additional monitoring and counting mechanisms

Engineering Contradiction:
ImproveRLF detection reliabilityVSAvoidDTX monitoring complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent configures maximum DTX thresholds in advance for different carrier scenarios (single carrier, multiple carriers with/without S-PSSCH). This preliminary configuration allows the device to directly compare actual DTX counts against pre-set thresholds, avoiding complex real-time decision logic and reducing processing complexity while maintaining reliable RLF detection

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent segments the RLF detection mechanism by implementing separate DTX counting and threshold comparison logic for different carrier configurations. Each carrier scenario has its own threshold value, allowing independent optimization and simplified management of detection parameters across multiple carriers without requiring a unified complex detection algorithm

Inventive Principle:
Principle #1Segmentation

2Reliability

If RLF detection is performed across all carriers, then communication reliability is improved, but detection complexity increases due to multi-carrier monitoring requirements

Engineering Contradiction:
Improvemulti-carrier RLF detection reliabilityVSAvoidmulti-carrier DTX detection difficulty
Core Design Contradiction:
ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

The patent applies different maximum DTX thresholds to different carrier scenarios: single carrier, multiple carriers with S-PSSCH, and multiple carriers without S-PSSCH. This localized threshold configuration optimizes detection sensitivity for each specific carrier arrangement, making the detection process simpler and more accurate by tailoring parameters to local conditions rather than using a universal complex detection mechanism

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent implements RLF detection by monitoring DTX on a subset of carriers (those configured for PC5-RRC connection) rather than requiring comprehensive monitoring of all possible carriers. This partial monitoring approach reduces detection complexity while maintaining sufficient reliability for the connected carriers that matter most for communication performance

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentEP4694557A1Method and device for performing communication in wireless communication system
Publication Date: 2026.02.11 LG ELECTRONICS INC
  • EP4694557A1 patent drawingFigure 1
  • EP4694557A1 patent drawingFigure 2
  • EP4694557A1 patent drawingFigure 3

AI summary

A method by which a first device performs wireless communication, and a device for supporting same are provided. The method may comprise the steps of: establishing a PCS-radio resource control (RRC) connection to a second device; acquiring information related to a maximum value of a discontinuous transmission (DTX) frequency for radio link failure (RLF) detection; and, with respect to all carriers related to the PC5-RRC connection, detecting an RLF on the basis that the DTX frequency reaches the maximum value of the DTX frequency. For example, the DTX frequency can be increased by 1 on the basis that physical sidelink feedback channel (PSFCH) reception is absent in a PSFCH reception opportunity related to a physical sidelink shared channel (PSSCH).