SRVCC Transcoding Avoidance via MSC CODEC Information Exchange
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Solution Overview
Problem
In 3GPP LTE systems, single radio voice call continuity (SRVCC) procedures often introduce additional transcoding points when a user equipment (UE) moves between packet switched (PS) and circuit switched (CS) networks, degrading voice call quality, especially for high-definition (HD) voice calls.
Innovation Solution
A mobile switching center (MSC) is configured to receive selected CODEC information from a mobility management entity (MME) and communicate it to a target MSC, enabling the target MSC to identify and use the same CODEC in the CS domain, thereby avoiding unnecessary transcoding during SRVCC procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If SRVCC procedures are implemented to enable voice call continuity between PS and CS networks, then call continuity is improved, but additional transcoding points are introduced degrading voice call quality
Solution Approach 1:
The source MSC performs preliminary actions by determining the CODEC used by the UE before handover, and includes this CODEC information in the handover request message sent to the target MSC. This preliminary preparation enables the target MSC to configure the appropriate CODEC in advance, avoiding transcoding during the actual handover execution and thus preventing voice call quality degradation while maintaining call continuity.
2Adaptability or versatility
If transcoding is performed during SRVCC to accommodate different network domains, then network compatibility is improved, but voice quality and call efficiency deteriorate
Solution Approach 1:
The invention copies the CODEC information from the source MSC to the target MSC through the handover request message. This copying mechanism allows the target MSC to reuse the same CODEC that the UE is already using, eliminating the need for transcoding operations. The CODEC information is transferred as data rather than physically moving the CODEC itself, enabling the target MSC to configure identical coding parameters and maintain voice quality across network domains.
3Adaptability or versatility
If multiple transcoding points are introduced during network transition, then network flexibility is improved, but system complexity and processing overhead increase
Solution Approach 1:
The invention extracts and removes the transcoding operation from the SRVCC handover process. By taking out the CODEC information directly from the source MSC and providing it to the target MSC, the patent eliminates the need for intermediate transcoding points. This extraction approach simplifies the system by removing unnecessary processing stages while maintaining the flexibility to support different network domains through information sharing rather than physical transcoding.
Data Source
AI summary
Technology for transcoding avoidance is disclosed. A mobile switching center (MSC) server can decode a single radio voice call continuity (SRVCC) packet switch (PS) to circuit switched (CS) request message received from a mobility management entity (MME) that includes selected CODEC information for a selected CODEC used for a user equipment (UE) in an internet protocol (IP) Multimedia Subsystem (IMS) over long term evolution (LTE) system. The MSC server can encode the selected CODEC information for transmission to a target MSC to enable the target MSC to identify the selected CODEC for the UE to allow the selected CODEC to be used in the CS domain.