IMS Session Control Path Switching Without Bearer Disruption
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Solution Overview
Problem
Existing methods for switching session control paths in IP multimedia core network subsystems often disrupt voice calls by terminating the related bearer paths, leading to user dissatisfaction due to limitations in data transfer and bandwidth in both CS and PS domains.
Innovation Solution
A method for switching session control paths from PS to CS or CS to PS without discontinuing calls, involving request and acknowledgement steps between UE and ICCF, allowing seamless transfer of session control information through the new path, and ensuring continuity of voice communication by maintaining the bearer control and bearer paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the session control path is switched by terminating the related session in prior art methods, then the session control path can be switched between CS and PS domains, but the voice call is disrupted and user satisfaction is degraded
Solution Approach 1:
The patent establishes a target session control path before terminating the source path. The UE receives indication information identifying the target path, performs media capability negotiation and path selection in advance, and only then terminates the source path. This preliminary establishment ensures seamless switching without call disruption.
Solution Approach 2:
The network device (MGCF or IMS CF) acts as an intermediary to coordinate the path switching process. It sends indication information to the UE, receives capability negotiation results, and manages the transition between source and target paths, ensuring the switching occurs without disrupting the ongoing voice call.
2Adaptability or versatility
If the bearer paths are released during session control path switching, then the session can be re-established on the new path, but the voice communication is interrupted
Solution Approach 1:
The patent performs media capability negotiation and target path establishment before releasing the source bearer paths. The UE and network device exchange capability information, select the target path, and prepare for switching in advance, ensuring that the bearer paths remain active during the transition and voice communication continues uninterrupted.
Solution Approach 2:
The patent maintains the bearer paths active throughout the switching process. Instead of releasing and re-establishing bearers, the system keeps the underlying transport paths continuous while only switching the session control plane, thereby maintaining uninterrupted voice communication throughout the path transition.
3Productivity
If the UE supports both CS and PS domains simultaneously for PS session control path, then greater bandwidth and service control capability are achieved, but the requirements for UE and network are higher
Solution Approach 1:
The patent enables dynamic selection between CS and PS session control paths based on network conditions, service requirements, and UE capabilities. The system can adaptively switch between domains without requiring permanent dual-domain configuration, reducing complexity while maintaining the ability to access high-capability PS services when available.
Data Source
AI summary
A method for switching the session control path of IMS centralized services is provided. When the condition for switching the session control path is satisfied during the ICS session based on the first session control path, the following steps are performed: one party of the ICS UE and ICCF of the ICS session transmits the request of switching the session control path to the other party; the receiving party identifies the ICS session corresponding to the request, and transmits an acknowledgement response to the transmitting party; and the ICCF and ICS UE set the session control path corresponding to the identified ICS session as the second session control path and transfer the subsequent session control information associated with the ICS session via the second session control path; wherein the first or second session control path is one of the PS session control path and the CS session control path.