S-CSCF Service Re-assignment via HSS Dynamic Registration Storage
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Solution Overview
Problem
In the 3GPP IMS system, S-CSCF re-assignment for registered users is only possible during the next registration procedure, leading to service unavailability until the next registration, which is inefficient and increases air interface traffic when a short re-registration timer is used.
Innovation Solution
Dynamic registration information is uploaded from S-CSCF to HSS during registration and downloaded during re-assignment, allowing S-CSCF reassignment without requiring operator intervention, using extended Cx-SAR/SAA operations and Reg Event package subscriptions to ensure seamless service continuity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If S-CSCF re-assignment is only performed during registration procedure, then service availability is maintained according to standard procedure, but service unavailability occurs until next registration when S-CSCF fails
Solution Approach 1:
The patent stores S-CSCF assignment information in HSS during the registration procedure in advance. When S-CSCF failure occurs, the stored information enables immediate re-assignment without waiting for next registration, thus performing the re-assignment action preliminarily prepared during registration.
Solution Approach 2:
The HSS acts as an intermediary that stores and manages S-CSCF assignment information. When S-CSCF fails, the HSS provides the stored assignment information to enable rapid re-assignment, mediating between the failed S-CSCF and the network to restore service continuity.
2Reliability
If re-registration timer is set to very small value to enable faster re-registration, then S-CSCF re-assignment can occur sooner, but air interface traffic increases significantly
Solution Approach 1:
The patent extracts the S-CSCF assignment information from the registration procedure itself and stores it separately in HSS. This allows re-assignment to be performed using the extracted stored information without requiring full re-registration, thus avoiding increased air interface traffic while enabling fast service recovery.
Solution Approach 2:
The assignment information is preliminarily stored in HSS during registration. When failure occurs, this pre-stored information enables immediate re-assignment without triggering frequent re-registration procedures, thus avoiding the energy loss from increased air interface traffic while maintaining fast recovery.
3Reliability
If manual operator intervention is used for S-CSCF re-assignment, then re-assignment can be performed, but operational complexity and costs increase
Solution Approach 1:
The system implements automatic S-CSCF re-assignment using stored assignment information in HSS. When S-CSCF fails, the network automatically performs re-assignment without requiring manual operator intervention, thus enabling the system to serve itself and eliminating operational complexity and costs while maintaining failover capability.
4Adaptability or versatility
If S-CSCF assignment information is not stored in HSS, then HSS database size remains smaller, but re-assignment during non-registration procedures is not possible
Solution Approach 1:
The S-CSCF assignment information is preliminarily stored in HSS during the registration procedure. This pre-stored information enables versatile re-assignment operations during non-registration procedures without requiring significant additional storage, as the information is already available in HSS from the initial registration.
Data Source
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AI summary
Re-assigning Serving Call Session Control Function, S-CSCF, services to a user of a Home Subscriber Server, HSS (200), in a Third Generation Partnership Program, 3GPP, telecommunications network is provided. In the case that S-CSCF services to the user including a registration procedure are previously assigned and access by the user to the S-CSCF services is erroneously lost, the proposal is to provide a method and means to re-assign those services. First, dynamic registration information (204) is uploaded from S-CSCF to the HSS (200) during the registration procedure. Then, the dynamic registration information (204) is stored from HSS (200) to S-CSCF (203) during a re-assignment procedure of the user.