Adaptation Unit for IMS Session Control Continuity After Inter-MSC Handover
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Solution Overview
Problem
Existing communication technologies fail to provide session control and service continuity for supplementary services in the IMS domain after an inter-MSC handover, limiting service availability to users when they move between different MSCs.
Innovation Solution
A method and system that includes an adaptation unit on the CS signaling path after an inter-MSC handover, which converts CS session control signaling messages into IMS session control signaling messages and vice versa, ensuring seamless session control across MSC boundaries by intercepting and converting signaling messages using E-interface or A-interface signaling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an access adaptation unit is installed between VMSC and UE to convert signaling, then session control can be provided in the IMS domain, but session control is lost after inter-MSC handover
Solution Approach 1:
An E-interface adaptation unit is introduced as an intermediary component between the VMSC and the E-interface network. This unit intercepts and converts CS signaling messages (such as REL, REL ACK, HOLD, HOLD ACK) into SIP signaling messages, enabling IMS domain session control to function properly after inter-MSC handover. The intermediary translates between different signaling protocols to maintain session control continuity across MSC boundaries.
Solution Approach 2:
The signaling path is segmented into distinct functional sections: the CS session leg between UE and access adaptation unit, and the IMS session leg between access adaptation unit and IMS network. The E-interface adaptation unit is positioned at a specific segmentation point to perform protocol conversion, allowing independent optimization of each segment while maintaining overall session control.
2Adaptability or versatility
If basic session control is provided through MGCF interworking, then IMS access is enabled, but supplementary service control is not supported
Solution Approach 1:
The E-interface adaptation unit performs preliminary conversion of CS signaling messages to SIP signaling messages before they reach the MGCF. By pre-converting supplementary service control messages (such as information elements in REL, HOLD, and other control messages) into their SIP equivalents, the system enables the MGCF to handle both basic call control and supplementary services without requiring complex additional processing.
Data Source
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AI summary
A method, system, and device for converting session control signaling are provided. The method includes at least one of the following steps: a first adaptation unit converts a session control signaling message of a circuit switched (CS) session leg into a session control signaling message of an IP multimedia subsystem (IMS) session leg; or the first adaptation unit converts a session control signaling message of an IMS session leg into a session control signaling message of a CS session leg. In embodiments of the present invention, an adaptation unit intercepts a CS signaling message after an inter-mobile switching center (MSC) handover, and converts CS signaling messages to IMS signaling messages and vice versa, so that the IMS domain may continue to control a session after the inter-MSC handover.