Heterogeneous Voice Call Anchoring in CS-IMS Networks
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Solution Overview
Problem
In heterogeneous communication systems, voice calls are inefficiently processed due to the need for multiple procedures when transitioning between CS and IMS domains, as the IMS domain anchors calls and reroutes them unnecessarily through the VCC AS.
Innovation Solution
A method and system that share subscriber information between the CS and IMS domains, allowing a voice call management server to register User Equipment in the IMS network, allocate a transfer number, and perform location registration in the circuit network, thereby bypassing the VCC AS for terminating CS calls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the IMS domain anchors all voice calls and reroutes them through the VCC AS for terminating CS calls, then domain selection and handoff control between CS and IMS domains is achieved, but call processing efficiency deteriorates due to unnecessary multiple procedures
Solution Approach 1:
The patent extracts the call anchoring function from the IMS domain for CS-to-IMS handoffs. Specifically, when a CS call is to be handed off to the IMS domain, the call is anchored in the CS domain's MGCF rather than being rerouted through the IMS domain's VCC AS. This extraction eliminates unnecessary rerouting procedures while preserving domain selection capability through the HLR's ability to determine the appropriate anchoring domain based on subscriber information.
2Adaptability or versatility
If the VCC AS anchors all calls to enable IMS-to-CS and CS-to-IMS domain transfer, then seamless handoff between domains is achieved, but system complexity increases due to the centralized anchoring requirement
Solution Approach 1:
The patent segments the call anchoring function based on the direction of handoff. For IMS-to-CS handoffs, the call is anchored in the IMS domain's VCC AS, while for CS-to-IMS handoffs, the call is anchored in the CS domain's MGCF. This segmentation eliminates the need for a universal centralized anchoring point, reducing system architecture complexity while maintaining seamless handoff capability through domain-specific anchoring strategies.
Solution Approach 2:
The patent inverts the conventional approach by allowing CS domain calls to be anchored in the CS domain rather than requiring all calls to be anchored in the IMS domain. This inversion reduces the burden on the IMS domain and VCC AS, simplifying the overall system architecture while maintaining handoff functionality through the HLR's intelligent routing decisions.
3Adaptability or versatility
If all terminating CS calls are rerouted to the IMS domain via the VCC AS, then unified call management across domains is achieved, but call processing time increases due to additional rerouting procedures
Solution Approach 1:
The patent performs preliminary action by having the HLR determine the appropriate anchoring domain before call setup. During the initial registration and location update processes, the HLR stores information about the subscriber's preferred domain and current location. When a call arrives, the HLR can immediately route the call to the correct anchoring domain (CS or IMS) based on pre-stored information, eliminating the need for runtime domain selection and reducing call processing time while maintaining unified call management.
Data Source
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AI summary
A communication system that manages heterogeneous networks including a Circuit Switched (CS) network and an Internet Protocol (IP) Multimedia Subsystem (IMS) network, and a method for processinga voice call in the communication system are provided. When a User Equipment (UE) requests the call setup by sending a Subscribe message including a subscriber identification number to a voice call management server of the IMS network, the voice call management server registers the UE in the IMS network and performs location registration in a Home Location Register (HLR) of the CS network using the subscriber identification number.