Network Node Codec Compatibility Switching for Seamless Handover
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Solution Overview
Problem
When a terminal in a mobile communication system hands over from a VoLTE network to a CS network, codec changes can disrupt call continuity, leading to quality deterioration or prolonged disconnection times due to transcoding or signaling delays.
Innovation Solution
A network node that detects codec changes and switches data transmission to a compatible mode, allowing seamless communication by generating and transmitting data in a compatible codec format, thereby avoiding transcoding and reducing disconnection times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If transcoding is performed to change codec between networks, then codec compatibility is improved, but call quality deteriorates and processing time increases
Solution Approach 1:
The network node performs preliminary codec negotiation and identifies compatible modes before handover occurs. By determining the compatible codec mode in advance (before the terminal actually hands over), the system prepares the appropriate codec parameters ahead of time, eliminating the need for quality-degrading transcoding during the critical handover moment while ensuring seamless codec compatibility.
2Adaptability or versatility
If transcoding is performed to change codec between networks, then codec compatibility is improved, but disconnection time increases
Solution Approach 1:
The system determines the compatible codec mode before handover execution, preparing all necessary codec parameters and transmission settings in advance. This preliminary action eliminates the time-consuming transcoding process that would otherwise occur during handover, thereby minimizing disconnection time while ensuring codec compatibility.
3Adaptability or versatility
If codec is changed during handover, then network compatibility is improved, but signaling complexity increases
Solution Approach 1:
The patent extracts the codec negotiation and compatibility determination process from the complex handover signaling chain. By having the network node independently determine compatible codec modes based on pre-configured information and terminal capabilities, the system removes the need for extensive real-time signaling exchanges between multiple network elements, thereby simplifying the overall signaling complexity while maintaining network compatibility.
4Reliability
If codec mode is switched to compatible mode, then communication continuity is maintained, but data transmission format changes
Solution Approach 1:
The network node changes the codec parameter (mode) to a compatible value that both networks can support. By switching to a compatible codec mode that is supported by both the VoLTE and CS networks, the system maintains communication continuity during handover. The parameter change is straightforward (selecting from pre-identified compatible modes) rather than requiring complex format conversion, thereby maintaining reliability while managing data format changes efficiently.
Data Source
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AI summary
A network node whereby there is no loss of communication quality and the call interruption time can be shortened to continue communication even when the codec used by one terminal during communication changes. In MSC/MGW (110) for forwarding data between two terminals when one of the two terminals performing communication in a first network transfers to a second network different from the first network, codec detector (804) detects both a first codec used by one terminal in the first network and a second codec used by one terminal in the second network. When the first codec is a codec having a mode compatible with the second codec, RTP payload generator (808) switches the codec of data transmitted from one terminal to the compatible mode of the first codec, thereby generating data for the other terminal, and transmitter (802) transmits the data for the other terminal to the other terminal.