Wireless Terminal Failure Reports With Cell Suitability Status

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Solution Overview

Problem

In cellular communications systems, when a User Equipment (UE) performs an inter-system voice fallback related handover and the handover fails, the UE stores a Radio Link Failure (RLF) report but does not log information about the selected cell, which is crucial for the network to determine if the cell was suitable or acceptable, leading to inefficiencies in network optimization.

Innovation Solution

The UE includes information in the RLF report indicating whether the selected cell was suitable or acceptable, along with the PLMN identity and emergency service availability, enabling the network to understand the failure context better.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of information

If the UE stores only basic RLF report information without cell suitability details, then the reporting process is simple and quick, but the network cannot determine whether the selected cell was suitable or acceptable, leading to ineffective network optimization

Engineering Contradiction:
Improvecell suitability informationVSAvoidreporting mechanism complexity
Core Design Contradiction:
Loss of informationVSDevice complexity

Solution Approach 1:

The UE performs cell suitability evaluation and stores the results in the RLF report before transmitting it to the network. This preliminary action ensures that the network receives complete information about whether the selected cell was suitable or acceptable, enabling effective network optimization without requiring additional complex evaluation mechanisms later.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If the UE includes detailed cell information in the RLF report, then the network can optimize handover processes effectively, but the report size and processing complexity increase

Engineering Contradiction:
Improvehandover optimization reliabilityVSAvoidreport data volume
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The patent extracts only the essential cell suitability information (whether the selected cell was suitable or acceptable) from the complete cell evaluation data. This selective extraction provides the network with the necessary information for handover optimization while keeping the report size manageable and avoiding unnecessary data transmission overhead.

Inventive Principle:
Principle #2Taking out (Extraction)

3Reliability

If the network implements comprehensive cell evaluation, then handover failures can be reduced, but the system complexity and signaling overhead increase

Engineering Contradiction:
Improvehandover success rateVSAvoidnetwork optimization complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The UE autonomously evaluates the suitability of selected cells and includes this evaluation in the RLF report without requiring additional network instructions or complex network-side evaluation mechanisms. This self-service approach enables reliable handover optimization while keeping the network side simple, as the UE performs the evaluation work locally and reports the results.

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP4578219B1Methods and apparatus for including information concerning the selected cell (suitable or acceptable cell) in a failure report
Publication Date: 2025.10.29 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
  • EP4578219B1 patent drawingFigure 1
  • EP4578219B1 patent drawingFigure 2
  • EP4578219B1 patent drawingFigure 3

AI summary

Systems and methods are disclosed for including information concerning a selected cell in a failure report. In one embodiment, a method performed by a wireless terminal comprises receiving a configuration from a first cell to perform handover to a second cell, the configuration comprising an indication indicating voice fallback purpose. The method further comprises attempting to connect to the second cell using a mobility procedure, determining that a failure has occurred, and storing information associated to the failure in a first report. The method further comprises attempting to perform cell selection in a same radio access technology as the second cell and, as a result, selecting a cell in the same radio access technology as the second cell. The method further comprises storing, in the first report, at least one piece of information that indicates whether the selected cell was a suitable cell or an acceptable cell.