Mobile Device Call Continuity During Network Handover

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Solution Overview

Problem

Existing communication systems face disruptions when moving a voice call from one communication session to another, such as from packet switched to circuit switched, due to delayed handover commands, leading to call drops.

Innovation Solution

A method where a mobile device receives a message to release resources for a first communication session, but refrains from doing so until a handover command is received or a predetermined time has expired, allowing for potential handover to a second access network to continue the call.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the mobile device releases resources upon receiving a release message, then resource management is efficient, but call continuity is disrupted due to delayed handover commands

Engineering Contradiction:
Improveresource management efficiencyVSAvoidcall continuity
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The mobile device performs preliminary checking of handover command status before executing resource release. The device waits to confirm whether a handover command will be received before releasing resources, preventing premature release that would disrupt call continuity. This preliminary verification action resolves the contradiction by ensuring resource release only occurs when handover is confirmed.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If the mobile device waits for handover command before releasing resources, then call continuity is maintained, but resource release is delayed

Engineering Contradiction:
Improvecall continuityVSAvoidresource release timing
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The mobile device implements a feedback mechanism by continuously monitoring for handover commands after receiving the release message. The device adjusts its resource release timing based on the feedback of whether a handover command is received or not. This feedback loop resolves the contradiction by dynamically determining the optimal resource release time rather than using a fixed approach.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP2816837B1Call Continuity when Moving from one Communication Session to another Communication Session
Publication Date: 2017.08.09 BLACKBERRY LTD
  • EP2816837B1 patent drawingFigure 1
  • EP2816837B1 patent drawingFigure 2
  • EP2816837B1 patent drawingFigure 3

AI summary

In some embodiments, there are disclosed systems and methods in which, when a mobile device receives a message indicating that the mobile device is to release resources pertaining to a communication session for a voice call over an access network, the mobile device refrains from performing this action to allow for the possible arrival and processing of a delayed handover command. The arrival of the handover command causes the mobile device to handover to a second access network to continue the voice call using a second communication session. This may help address situations in which the handover command is delayed in the network and is therefore delayed in reaching the mobile device.