EPS Fallback Voice Call Signaling for Bearer State Synchronization

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Solution Overview

Problem

In wireless cellular communication networks, particularly during transitions from 5G to 4G, issues arise with voice bearer establishment, leading to no sound or call drops due to unsynchronized network states, affecting user experience.

Innovation Solution

Implementing a communication method that includes sending specific signaling (e.g., 200 OK and a=curr:qos local sendrecv) before EPS fallback occurs, ensuring resource reservation and synchronized voice bearer states between terminal devices.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the terminal device falls back from 5G to 4G network during a voice call, then network coverage is improved, but voice bearer establishment time is delayed causing no sound or call drops

Engineering Contradiction:
Improvenetwork coverageVSAvoidvoice bearer establishment
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent applies preliminary action by having the called terminal device send the 200 OK signaling with a=curr:qos local sendrecv parameter before the EPS fallback process is completed and before the fourth signaling with QCI=1 is received. This advance indication allows the first terminal device to prepare for voice bearer establishment on the 4G network, ensuring timely voice transmission despite the network transition delay.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If the called terminal sends 200 OK signaling with a=curr:qos local sendrecv before receiving QCI=1 signaling, then voice bearer establishment success rate is improved, but signaling sequence complexity increases

Engineering Contradiction:
Improvevoice bearer establishment success rateVSAvoidsignaling sequence
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements feedback by having the called terminal device send the 200 OK signaling with the a=curr:qos local sendrecv parameter, which provides real-time feedback about the voice bearer status to the first terminal device. This feedback mechanism enables both terminals to synchronize their understanding of the voice bearer establishment state, improving reliability despite the added signaling step.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP4451659B1Voice call method and apparatus, computer readable storage medium, and chip system
Publication Date: 2026.02.25 HONOR DEVICE CO LTD
  • EP4451659B1 patent drawingFigure 1A
  • EP4451659B1 patent drawingFigure 1B
  • EP4451659B1 patent drawingFigure 1C

AI summary

A method and an apparatus for improving voice call quality in an EPSFB scenario are provided, which are applied to the communication field. This method provides an optimization solution for refreshing a resource reservation state to resolve a problem of dual-terminal no sound, call drop, or call drop after no sound during a call between a caller terminal and a called terminal due to signaling disorder in the EPSFB scenario, effectively improving a success rate for refreshing a call state in the current scenario and ensuring a normal voice for a terminal in an abnormal scenario.