S-CSCF Location Retrieval via HSS Mediator in IMS Networks
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Solution Overview
Problem
The Serving-Call Session Control Function (S-CSCF) in an IP Multimedia Subsystem (IMS) network lacks access to location information for registered contacts using mobile access, which is crucial for validating SIP requests and charging purposes, especially when multiple contacts are registered simultaneously.
Innovation Solution
The S-CSCF receives location information for a second contact associated with the same IMPU but different access type by requesting it from the Home Subscriber Server (HSS) or receiving it from the Interrogating CSCF (I-CSCF), ensuring accurate addition or modification of the P-Access-Network-Info (PANI) header.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the S-CSCF relies on existing contact registration information, then device complexity is reduced, but location information completeness deteriorates
Solution Approach 1:
The patent introduces the HSS as an intermediary component that stores and provides location information for mobile contacts. When the S-CSCF needs location information for a contact, it queries the HSS which returns the stored location data. This mediator approach allows the S-CSCF to obtain complete location information without increasing its own complexity, as the HSS handles the location information management centrally.
2Loss of information
If the S-CSCF requests location information from HSS for every contact, then location information completeness is improved, but use of energy increases
Solution Approach 1:
The patent implements preliminary action by having the HSS store location information when contacts are initially registered with mobile access. This pre-stored information is then readily available when the S-CSCF needs it, eliminating the need for repeated location information requests. The location information is prepared in advance and cached in the HSS, reducing subsequent signaling and energy consumption.
Solution Approach 2:
The patent applies local quality by differentiating the handling of location information based on contact type. For mobile contacts, location information is stored and retrieved from HSS, while for non-mobile contacts, existing registration information suffices. This targeted approach ensures location information completeness for mobile contacts without unnecessarily querying the HSS for all contacts, thus optimizing energy usage.
3Reliability
If the S-CSCF validates SIP requests with location information, then reliability is improved, but device complexity increases
Solution Approach 1:
The HSS acts as an intermediary that centralizes the storage and provision of location information, allowing the S-CSCF to perform reliable SIP request validation without bearing the complexity of location information management. The S-CSCF simply queries the HSS for location data when needed, maintaining validation reliability while keeping its own complexity low.
Data Source
AI summary
A method and apparatus for providing location information to a CSCF in an IMS network. An S-CSCF registers a first contact associated with an IMPU, and receives location information associated with the first contact. A second contact associated with the same IMPU, and also with a mobile access, is then registered at the S-CSCF. The S-CSCF receives location information associated with the second contact.