Voice Fallback Handover RLF Reporting for NR-LTE Optimization

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Solution Overview

Problem

Current RLF reports in NR to LTE handovers do not distinguish between normal mobility-related handovers and voice fallback handovers, making it difficult to optimize handover parameters effectively.

Innovation Solution

Enhance RLF reports with an indication to differentiate between voice fallback-related and other NR to LTE handovers by including an indication in the RLF report that the last completed handover was for voice fallback purposes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If RLF reports include detailed handover information, then measurement precision improves, but device complexity increases

Engineering Contradiction:
Improvehandover identification accuracyVSAvoidreport structure complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts only the essential handover identification information (voice fallback indication) from the complete handover context and includes it in the RLF report. This selective extraction maintains measurement precision for handover identification while avoiding the complexity of including all possible handover details in the report.

Inventive Principle:
Principle #2Taking out (Extraction)

2Reliability

If RLF reports differentiate between handover types, then reliability of optimization improves, but loss of information increases

Engineering Contradiction:
Improvehandover optimization reliabilityVSAvoidhandover context information
Core Design Contradiction:
ReliabilityVSLoss of information

Solution Approach 1:

The patent introduces an intermediary indicator (voice fallback indication) that bridges the gap between different handover types and the optimization process. This indicator enables reliable differentiation of handover types for optimization purposes without requiring the RLF report to contain complete contextual information about each handover, thus maintaining reliability while minimizing information loss.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP4569926B1On ho type information associated to voice fallback handover
Publication Date: 2025.08.06 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
  • EP4569926B1 patent drawingFigure 1
  • EP4569926B1 patent drawingFigure 2
  • EP4569926B1 patent drawingFigure 3

AI summary

Systems and methods are disclosed that relate to radio link failure reporting with an indication that indicates whether a last successfully completed handover was for voice fallback purposes. In one embodiment, a method performed by a User Equipment (UE) comprises receiving, from a first network node belonging to a first radio access technology, a configuration to perform a handover to a second network node belonging to a second radio access technology, the configuration comprising an indication that indicates that the handover is for voice fallback purpose. The method further comprises connecting to a cell served by the second network node and, responsive to declaring a radio link failure in the cell served by the second network node and the indication, storing information associated to the radio link failure in a report, the information comprising an indication that a last completed handover was for voice fallback purpose.