Home Network Domain Selection for Routing Visited Network Calls
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Solution Overview
Problem
In the context of IMS network architecture, when user equipment (UE) roams to a visited network, the differences in timer durations and signaling mechanisms between the CS domain on the visited network and the IMS domain on the home network can prevent supplementary services, such as late forwarding services, from being normally triggered, as the visited network may struggle to return failure cause values in real time to the home network.
Innovation Solution
A call control device on the home network determines whether it communicates with the visited network using a CS domain and sends an access domain confirmation response message to route calls through the CS domain, allowing the visited network to trigger services without needing to return service information to the home network in real time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the visited network returns service information to the home network in real time, then the IMS domain on the home network can trigger services, but timer and signaling differences between networks prevent normal service triggering
Solution Approach 1:
The patent introduces a domain selection indicator as an intermediary mechanism that determines whether to use CS domain or IMS domain for service control. This indicator acts as a mediator that resolves the complexity of real-time communication between visited network and home network by pre-configuring the appropriate domain based on network conditions and capabilities, thereby avoiding the timer and signaling compatibility issues.
Solution Approach 2:
The patent changes the domain selection parameter dynamically based on network conditions. By modifying the domain selection indicator according to whether the visited network supports real-time service information return, the system adapts between CS domain and IMS domain control, resolving the reliability issue caused by timer and signaling differences without increasing overall system complexity.
2Stability of the object's composition
If the IMS domain on the home network controls all services, then service consistency is achieved, but the visited network cannot normally trigger services due to timer and signaling differences
Solution Approach 1:
The patent makes the service control domain dynamic rather than fixed. The domain selection indicator allows the system to switch between IMS domain control (for service consistency) and CS domain control (for reliable service triggering). This dynamic adjustment resolves the contradiction by adapting the control mechanism to the specific network conditions and service requirements.
Solution Approach 2:
The patent segments the service control function into two independent domains: IMS domain for services requiring consistency and CS domain for services requiring reliable triggering. By dividing the monolithic IMS control into separate domain-specific control paths, the system can maintain service consistency where needed while ensuring reliable service triggering in other scenarios.
3Productivity
If the CS domain is used for communication between home network and visited network, then service triggering can be controlled locally, but real-time service information return to home network is not needed
Solution Approach 1:
The patent extracts the real-time service information return requirement from the CS domain communication path. By using the domain selection indicator to route service triggering locally in the CS domain without requiring information return to the home network, the system achieves efficient local service control while eliminating the need for real-time information exchange that would cause delays and compatibility issues.
Data Source
AI summary
Embodiments provide a call control device, an HSS, an AS, and a user service processing method. The call control device includes: a receiving module, configured to: receive an access domain confirmation request message, comprising an identifier of the called UE, sent by a call routing device on a home network; a determining module determining, according to the identifier, that the home network communicates with a visited network of the called UE by using a CS domain on the home network; and a sending module sending an access domain confirmation response message, carrying instruction information, to the call routing device and the instruction information is used to instruct the call routing device to route the call to the visited network by using the CS domain on the home network.