Cell Reselection Parameter Adjustment for LBT Failure Mitigation

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Solution Overview

Problem

In existing communication systems, after consecutive Listen Before Talk (LBT) failures, user equipment (UE) tends to reselect the previous cell, leading to repeated LBT failures and inefficient use of unlicensed spectrums.

Innovation Solution

The method involves camping on a current serving cell after consecutive LBT failures exceed a preset threshold, then decreasing at least one reselection parameter value of the previous cell and determining a set of target cells based on reselection parameter values. The target cells are sorted, and the top-ranked cells are selected for cell reselection, reducing the likelihood of reselecting the previous cell.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the UE reselects cells based on existing techniques after LBT consecutive failures, then the cell reselection process is simple, but the UE is prone to select the previous cell again, resulting in repeated LBT failures

Engineering Contradiction:
Improvecell reselection success rateVSAvoidcell reselection process complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent modifies cell reselection parameters by introducing a penalty mechanism. When LBT consecutive failures occur, the UE adjusts the cell priority or reselection threshold parameters for the previous cell, making it less likely to be selected again. This parameter change resolves the contradiction by improving reliability through differentiated parameter treatment while maintaining the overall simplicity of the reselection process.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent implements a feedback mechanism where the UE monitors LBT failure events and uses this information to adjust subsequent cell reselection decisions. The feedback loop involves detecting LBT failures, identifying the previous cell, and modifying reselection behavior based on this historical information. This feedback approach improves reliability by learning from past failures while keeping the process manageable through structured feedback handling.

Inventive Principle:
Principle #23Feedback

2Productivity

If the UE continuously attempts to access the previous cell after LBT failures, then the access attempts are persistent, but the unlicensed spectrum resources are wasted due to repeated failures

Engineering Contradiction:
Improvechannel access efficiencyVSAvoidspectrum resource waste
Core Design Contradiction:
ProductivityVSLoss of energy

Solution Approach 1:

The patent changes access parameters dynamically based on LBT failure history. When failures are detected, the UE modifies parameters such as access thresholds, priority levels, or timing parameters for the previous cell. This parameter adaptation improves channel access efficiency by redirecting attempts to more suitable cells while reducing energy waste from persistent failures on problematic cells.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent performs preliminary assessment of cell suitability before attempting access. By evaluating LBT failure history and adjusting cell selection criteria in advance, the UE avoids wasting energy on cells with poor access conditions. This preliminary action mechanism improves productivity by pre-filtering suitable targets and prevents energy loss by avoiding predetermined failure scenarios.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3920593B1Cell reselection method, device, storage medium, and user terminal
Publication Date: 2025.04.09 SPREADTRUM COMMUNICATION (SHANGHAI) CO LTD
  • EP3920593B1 patent drawingFigure 1~2
  • EP3920593B1 patent drawingFigure 3~4
  • EP3920593B1 patent drawing

AI summary

Provided are a cell reselection method, device, a storage medium, and a user terminal, the method includes: if the number of consecutive failures of the LBT in the previous cell exceeds a preset threshold, residing in the current serving cell; when the current serving cell requires to perform cell reselection, reducing at least one reselection parameter value of the previous cell, and determining the set of target cells according to the reselection parameter value of each cell; sorting the target cells in the set; selecting the top sorted target cell sequentially to perform cell reselection. The solution of the present invention can reduce the possibility of reselecting the previous cell.