NR-U User Equipment LBT Failure Counting for Mobility Control

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Solution Overview

Problem

In NR-U communication systems, the existing mobility control methods do not effectively address the challenges posed by Listen Before Talk (LBT) failures in unlicensed bands, which can lead to interruptions in radio communication despite satisfactory signal quality.

Innovation Solution

A communication control method where user equipment receives a threshold from a serving cell, counts LBT failures over a predetermined period, and transmits information identifying the cell with excessive LBT failures to the serving cell, enabling improved mobility control in NR-U systems.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If mobility control methods are used in NR-U systems, then cell switching can be performed, but radio communication interruptions occur due to LBT failures despite satisfactory signal quality

Engineering Contradiction:

Improveradio communication continuityVSAvoidmobility control effectiveness

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent implements a feedback mechanism where the user equipment monitors LBT failure counts from multiple cells and reports this information to the network. The network uses this feedback to make informed mobility control decisions, switching between cells based on actual LBT success rates rather than just signal quality, thereby reducing communication interruptions while maintaining effective mobility management

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent performs preliminary monitoring and counting of LBT failures in multiple cells before executing mobility control decisions. By accumulating LBT failure statistics over a predetermined period in advance, the system can predict which cells are likely to cause interruptions and proactively select alternative cells, preventing communication interruptions before they occur

Inventive Principle:

Principle #10Preliminary action

2Reliability

If LBT is performed in unlicensed bands, then channel access is controlled, but communication interruptions increase due to LBT failures

Engineering Contradiction:

Improvechannel access reliabilityVSAvoidcommunication throughput

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent changes the parameter used for mobility control from traditional signal quality metrics to LBT failure counts. By monitoring and comparing LBT failure statistics across multiple cells, the system can identify cells with poor channel access reliability and switch to alternative cells, thereby maintaining communication throughput while improving channel access reliability through data-driven parameter selection

Inventive Principle:

Principle #35Parameter changes

3Ease of operation

If signal quality is used for mobility control, then cell selection is simplified, but LBT failures cause interruptions despite good signal quality

Engineering Contradiction:

Improvecell selection simplicityVSAvoidcommunication continuity

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent performs preliminary monitoring of LBT failures in multiple cells before making mobility control decisions. By accumulating LBT failure statistics over a predetermined period in advance, the system can predict which cells are likely to cause interruptions and proactively select alternative cells, preventing communication interruptions before they occur

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS20250159575A1Communication control method and user equipment

Publication Date: 2025.05.15 KYOCERA CORP

AI summary

A communication control method used in a user equipment. The communication control method comprises receiving, from a serving cell of the user equipment, a threshold; counting, in a predetermined period, a number of Listen Before Talk (LBT) failures in a cell; and in response to the number of the LBT failures being greater than or equal to the threshold received from the serving cell, transmitting, to the serving cell, information identifying the cell in which the number of the LBT failures being greater than or equal to the threshold.