Sidelink Communication in Unlicensed Bands with Band-Specific DTX Detection

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Solution Overview

Problem

The increasing demand for mobile broadband communication and V2X services requires efficient sidelink communication solutions, particularly in unlicensed bands, to address reliability and latency issues in wireless communication systems.

Innovation Solution

A method and device for sidelink communication that involves obtaining configuration information for physical sidelink feedback channels, determining maximum numbers of discontinuous transmissions for radio link failure detection, and transmitting sidelink control information to detect radio link failure based on absent feedback channel receptions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If sidelink communication is performed in unlicensed band, then communication capacity is increased, but reliability and latency performance deteriorate due to difficulty in detecting radio link failure

Engineering Contradiction:
Improvecommunication capacityVSAvoidreliability and latency performance
Core Design Contradiction:
Quantity of substanceVSReliability

Solution Approach 1:

The patent segments the maximum number of DTX parameters into two distinct values: one for licensed band and another for unlicensed band. This segmentation allows the system to apply band-specific thresholds for RLF detection, thereby improving reliability in unlicensed bands without compromising the communication capacity benefits of using those bands.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies local quality by configuring different maximum DTX values specifically for unlicensed band operations. Instead of using a uniform threshold across all bands, the system tailors the RLF detection sensitivity to the specific characteristics of unlicensed spectrum, enhancing reliability where it is most needed while preserving the high capacity advantages of unlicensed band communication.

Inventive Principle:
Principle #3Local quality

2Device complexity

If a single maximum number of DTXs is used for both licensed and unlicensed bands, then device complexity is reduced, but measurement precision deteriorates due to inability to detect RLF accurately in unlicensed band

Engineering Contradiction:
Improveconfiguration complexityVSAvoidRLF detection accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent divides the RLF detection mechanism into two separate configurations based on band type. By maintaining distinct maximum DTX values for licensed and unlicensed bands, the system achieves precise RLF detection in unlicensed bands without requiring complex adaptive logic, thus balancing measurement precision with manageable device complexity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent changes the parameter value of maximum DTX based on the operating band. This parameter adaptation allows the system to optimize RLF detection accuracy for unlicensed bands by using a higher threshold that accounts for the different channel characteristics, while keeping the overall mechanism simple through straightforward parameter selection rather than complex real-time adjustment.

Inventive Principle:
Principle #35Parameter changes

3Measurement precision

If maximum number of DTXs is increased for unlicensed band, then RLF detection accuracy is improved, but loss of time increases due to longer detection period

Engineering Contradiction:
ImproveRLF detection accuracyVSAvoiddetection time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent applies local quality by setting a higher maximum DTX threshold specifically for unlicensed band operations. This localized adjustment improves RLF detection accuracy in unlicensed bands by allowing more transmission attempts before declaring failure, while the threshold remains fixed to avoid unnecessary detection delays, thus balancing accuracy with time efficiency.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent adjusts the maximum DTX parameter value based on band characteristics. For unlicensed bands, a higher threshold is configured to account for potential temporary channel issues, improving detection accuracy without excessively extending the detection period. The parameter change is static and band-specific, avoiding the time loss that would result from dynamic adjustment or overly conservative thresholds.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP4593519A1Method and device for performing sidelink communication in unlicensed band
Publication Date: 2025.07.30 LG ELECTRONICS INC
  • EP4593519A1 patent drawingFigure 1
  • EP4593519A1 patent drawingFigure 2
  • EP4593519A1 patent drawingFigure 3

AI summary

Provided are a method performed by a first device in a wireless communication system, and a device supporting same. The method may comprise the steps of: acquiring configuration information related to a physical sidelink feedback channel (PSFCH); acquiring information related to a first maximum number of discontinuous transmissions (DTXs) for sidelink (SL) radio link failure (RLF) detection; acquiring information related to a second maximum number of DTXs for SL RLF detection in an unlicensed band; transmitting, via a physical sidelink control channel (PSCCH), first sidelink control information (SCI) for scheduling second SCI and a physical sidelink shared channel (PSSCH); transmitting the second SCI and data via the PSSCH; increasing the number of DTXs by 1 on the basis of failing to receive a PSFCH in a PSFCH reception occasion associated with the PSSCH; and detecting a SL RLF on the basis that the number of DTXs reaches the first maximum number of DTXs or the second maximum number of DTXs. For example, the information related to the second maximum number of DTXs may be configured independently from the information related to the first maximum number of DTXs.