Mobile Device Call Continuity During Handover Delays
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Solution Overview
Problem
Existing methods for transferring voice calls from one communication session to another, such as from packet switched to circuit switched, often result in call disruptions due to delayed handover commands, leading to premature release of resources and call termination.
Innovation Solution
A method where a mobile device refrains from releasing resources for a predetermined time after receiving a message to release resources, allowing for potential arrival of a handover command, thereby enabling a seamless transfer to a new communication session if the command is received during this time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the mobile device immediately releases resources upon receiving a message to release resources, then resource management is efficient and responsive, but call continuity is disrupted when handover commands are delayed
Solution Approach 1:
The mobile device performs preliminary actions by releasing resources immediately upon receiving the message, but then takes a corrective preliminary action by sending a keepalive message if a handover command hasn't been received within a threshold time. This resolves the contradiction by initially prioritizing resource management efficiency while having a backup mechanism to preserve call continuity.
Solution Approach 2:
The system implements feedback through monitoring whether a handover command is received within the threshold time. If not received, the mobile device sends a keepalive message to the access network, creating a feedback loop that adjusts resource management based on handover status. This resolves the contradiction by dynamically responding to handover command arrival status.
2Reliability
If the mobile device waits for handover command before releasing resources, then call continuity is maintained, but resource management efficiency decreases due to delayed resource release
Solution Approach 1:
The mobile device performs preliminary resource release immediately upon receiving the message, then takes a corrective action by sending a keepalive message if needed. This reverses the traditional approach of waiting, instead prioritizing resource management efficiency while maintaining call continuity through the keepalive mechanism.
Solution Approach 2:
The system uses feedback from the absence or presence of a handover command within the threshold time to determine whether to send a keepalive message. This feedback mechanism allows the system to prioritize resource management efficiency while preserving call continuity when handover is occurring.
3Loss of time
If the handover command is delayed, then network processing time is extended, but call termination occurs prematurely due to resource release
Solution Approach 1:
The mobile device performs preliminary resource release immediately, then takes a corrective action by sending a keepalive message to prevent call termination if the handover command is delayed. This resolves the contradiction by initially allowing fast resource management while having a backup to ensure call completion.
Solution Approach 2:
The system implements feedback by monitoring whether the handover command arrives within the threshold time. If delayed, the mobile device sends a keepalive message to the access network, creating a feedback loop that prevents premature call termination and ensures call completion despite handover delays.
4Reliability
If the mobile device sends keepalive message continuously, then call continuity is ensured, but network signaling overhead increases
Solution Approach 1:
The mobile device sends the keepalive message periodically only when needed - specifically, when a handover command has not been received within the threshold time. This periodic, conditional action ensures call continuity while minimizing unnecessary network signaling overhead compared to continuous keepalive messages.
Solution Approach 2:
The system uses feedback from the handover command reception status to control keepalive message transmission. The keepalive message is sent only when the handover command is delayed beyond the threshold time, creating a feedback-based mechanism that ensures call continuity while reducing network signaling overhead by avoiding unnecessary messages.
Data Source
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.