SRVCC Media Path Switching via eMSC and ICP Anchoring
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing SRVCC methods require an update operation to the remote leg, leading to long transmission delays and interruptions in communication due to the relatively long IMS signaling delay.
Innovation Solution
The method involves anchoring IMS session signaling to an IMS Control Point (ICP) and media to an Access Gateway (AGW) controlled by the ICP, with the eMSC preparing a media link resource and sending a call request to the ICP to correlate the media link with the remote leg media link, using SIP or ISUP protocols for handover requests.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an update operation to the remote leg is performed during SRVCC handover, then the service continuity is maintained, but the transmission delay increases and communication interruption occurs due to IMS signaling delay
Solution Approach 1:
The patent performs media path switching preparation in advance by establishing a pre-switching media path through the eMSC before the handover occurs. The eMSC prepares the CS domain media path and correlates it with the IMS session in advance, so that when handover is triggered, the media path can be switched immediately without waiting for remote leg update signaling, thus reducing transmission delay and communication interruption
Solution Approach 2:
The patent separates the signaling path and media path independently. The signaling path continues to go through the IMS network (P-CSCF, S-CSCF) for session management, while the media path is switched to the CS domain through the eMSC. This segmentation allows the media path to be switched without affecting the signaling path, enabling faster handover without requiring remote leg update operations
2Reliability
If the IMS session is handed over from PS network to CS network, then the voice call continuity is achieved, but the complexity of the handover process increases due to multiple network domains involved
Solution Approach 1:
The patent introduces the eMSC as an intermediary node that bridges the IMS network and CS network. The eMSC receives handover requests from the PS network control element, prepares the CS domain media path, correlates the media path with the IMS session, and manages the handover process. This intermediary simplifies the handover process by centralizing the coordination functions and providing a clear interface between the two network domains
Solution Approach 2:
The patent merges the handover control functions with the existing eMSC infrastructure. The eMSC integrates multiple functions including receiving handover requests, preparing media paths, correlating sessions, and managing both IMS and CS domain resources. This merging reduces the need for separate dedicated handover management entities and simplifies the overall system architecture
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
A method for realizing a single radio voice call continuity and a single radio voice call continuity system are disclosed. After a UE-1 establishes an IMS session with a remote leg through a PS network, wherein in the IMS session, signaling is anchored to an ICP and media is anchored to an AGW controlled by the ICP, the method is realized as follows: sending a handover request by a control net element of the PS network to an eMSC to request a handover of the IMS session to a CS network access mode; after receiving the handover request, preparing a media link resource by the eMSC for the UE-1 to communicate with the eMSC and sending a call request to the ICP; and controlling the AGW to correlate a media link established by the call request with a remote leg media link of the IMS session by the ICP. The method can effectively solve the problem existing in the prior art that the duration of interruption is too long, and improve user experience.