IMS S-CSCF Restoration Using Cached P-CSCF Binding
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Solution Overview
Problem
Network outages in the IP Multimedia Subsystem (IMS) cause unreachable network nodes, leading to service quality degradation and call failures due to the lack of effective restoration of Proxy Serving Call Session Control Function (P-CSCF) binding information when a Serving Call Session Control Function (S-CSCF) becomes unavailable.
Innovation Solution
Storing P-CSCF binding information in a cache or external database accessible to network nodes like the Telephony Application Server (TAS) or Home Subscriber Server (HSS/HLR) allows a replacement node to retrieve this information, enabling seamless communication without triggering new registration processes and reducing signaling overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If P-CSCF binding information is stored in cache or external database, then service restoration speed improves, but network infrastructure complexity increases
Solution Approach 1:
The patent implements preliminary action by storing P-CSCF binding information in advance in caches maintained by network nodes (TAS, HSS/HLR) before the S-CSCF becomes unavailable. This pre-stored information enables immediate service restoration without waiting for new registration processes when failures occur.
Solution Approach 2:
The patent introduces intermediary elements (cache memory in TAS and HSS/HLR) that store P-CSCF binding information. These intermediaries act as mediators between the unavailable S-CSCF and the network, allowing service restoration without direct S-CSCF involvement during failure conditions.
2Reliability
If new registration process is triggered upon S-CSCF unavailability, then network security is maintained, but signaling overhead increases
Solution Approach 1:
The patent applies partial action by using pre-stored P-CSCF binding information for service restoration without completing a full new registration process. This partial approach maintains essential security while avoiding the complete signaling overhead of a full registration, striking a balance between security and efficiency.
Solution Approach 2:
The patent uses copying by retrieving and reusing previously stored P-CSCF binding information from caches instead of generating entirely new binding information through a complete registration process. This copying approach reduces signaling while maintaining network security through verified pre-authenticated data.
3Device complexity
If S-CSCF binding information is not restored, then network simplicity is maintained, but call failure rate increases
Solution Approach 1:
The patent implements self-service by enabling network nodes (TAS, HSS/HLR) to autonomously retrieve and use stored P-CSCF binding information from their own caches when S-CSCF becomes unavailable. This self-service mechanism restores services without complex external coordination, maintaining relative network simplicity while reducing call failures.
Data Source
AI summary
Systems, methods, and devices that relate to prompt restoration of Internet Protocol (IP) Multimedia Subsystem (IMS) services when a Serving Call Session Control Function (S-CSCF) becomes unavailable are disclosed. In one example aspect, a method for wireless communication includes receiving, by a first network node in a network, a user profile associated with a user device from a home server configured to manage subscriber information. The user profile comprises binding information about a Proxy Call Session Control Function (P-CSCF) that is in communication with the user device. The method also includes retrieving, by a second network node, the binding information of the P-CSCF upon a third network node being unreachable for completing a call for the user device to enable a completion of the call for the user device.