Terminal Domain Selection for Mobile Call Termination
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Solution Overview
Problem
Existing solutions for mobile terminating calls in dual mode CS/IMS systems require additional signaling to determine the capability of IP-CANs for real-time conversational speech/video services, leading to increased complexity and overhead, as the IMS network needs to know about the IP-CAN and local access network capabilities.
Innovation Solution
The terminal is empowered to decide the domain for call termination based on the access network's capability, reducing signaling complexity and overhead, with the option to use PS or USSD control channels, while maintaining operator control through communicated policy, allowing the UE to indicate a CS bearer for media transport when VoIP is not supported.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the IMS network determines the domain for call termination by checking IP-CAN and access network capabilities, then the network can make informed routing decisions, but the signaling overhead and network complexity increase significantly
Solution Approach 1:
Instead of having the network query the terminal about its capabilities and then make the domain selection decision, the invention inverts the approach by having the terminal autonomously determine the appropriate domain for call termination based on its own capability assessment, thereby reducing network signaling complexity while maintaining reliable domain selection
Solution Approach 2:
The terminal performs self-assessment of its capabilities (VoIP capability, simultaneous CS/PS capability) and autonomously decides the domain for call termination without requiring extensive network querying or complex network-side processing, thus reducing signaling overhead while maintaining accurate domain selection
2Device complexity
If the terminal autonomously determines the domain for call termination based on its capability, then signaling overhead is reduced, but the network loses direct control over domain selection
Solution Approach 1:
The terminal provides feedback information about its capabilities (VoIP capability, simultaneous CS/PS capability) to the network, allowing the network to be informed of the terminal's status while the terminal maintains autonomous decision-making authority, thus balancing reduced signaling overhead with maintained network awareness
3Ease of operation
If the network provides detailed capability information to the terminal to aid domain selection, then the terminal can make more accurate domain decisions, but the signaling requirements and network overhead increase
Solution Approach 1:
The terminal performs preliminary self-assessment of its capabilities (determining VoIP capability and simultaneous CS/PS capability) before the call termination decision is needed, so that when domain selection is required, the terminal already has the necessary information to make an autonomous decision without requiring additional network signaling
Data Source
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AI summary
There is discussed a method of selecting an access domain for receiving a speech and/or video call at a mobile station of a mobile communications network in which calls are routed via a central service control common to a plurality of access domains. The method comprises the central service control transmitting an invite to establish a call to the terminating mobile station; the mobile station deciding on an access domain for receiving the call taking into account the capabilities of the local access network, and transmitting the selected access domain to the central service control; and establishing the call in accordance with the selected access domain.