HSS-Based IMS Session Restoration After S-CSCF Failure
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Solution Overview
Problem
Existing IMS restoration procedures disrupt communication sessions and consume excessive network bandwidth due to unneeded communications between IMS nodes when a node becomes unavailable, leading to noticeable delays and increased load on the network.
Innovation Solution
Storing P-CSCF node information at the HSS allows direct interaction to select an optimal replacement S-CSCF node based on capability matching, minimizing communication between nodes and avoiding session teardown.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing IMS restoration procedures are used to handle node unavailability, then the communication session can be restored, but the service is disrupted and noticeable delays occur
Solution Approach 1:
The patent pre-establishes backup S-CSCF nodes and stores their information in advance before any failure occurs. When a primary S-CSCF node fails, the system can immediately switch to the pre-prepared backup node without needing to perform discovery or selection procedures during the restoration process, thereby eliminating noticeable delays while ensuring reliable session restoration
2Reliability
If existing IMS restoration procedures are used to handle node unavailability, then the communication session can be restored, but unneeded communications between IMS nodes consume excessive network bandwidth
Solution Approach 1:
The system pre-configures backup S-CSCF nodes with all necessary information including UE profiles and service data before failures occur. This preliminary preparation eliminates the need for backup nodes to communicate with other IMS nodes for information retrieval during restoration, significantly reducing network bandwidth consumption while maintaining reliable session restoration
Solution Approach 2:
The patent introduces an HSS (Home Subscriber Server) as an intermediary that centrally stores and manages all S-CSCF node information and UE profiles. The HSS acts as a mediator that provides pre-retrieved information to backup nodes during restoration, eliminating the need for backup nodes to directly communicate with other IMS nodes and thereby reducing overall network bandwidth consumption
3Ease of operation
If backup IMS nodes transmit requests to other IMS nodes for additional information during restoration, then the backup node can be configured, but processor load on the network increases
Solution Approach 1:
The system performs all information retrieval and backup node configuration operations in advance, before any node failure occurs. Backup S-CSCF nodes are pre-configured with complete UE profiles and service information stored in the HSS, eliminating the need for processor-intensive communication and information retrieval operations during the actual restoration process, thereby reducing network processor load while maintaining ease of operation
Data Source
AI summary
Techniques are described herein for providing improved service call session restoration. In embodiments, such techniques may comprise storing, at a home subscriber server (HSS), information about a proxy call session control function (P-CSCF) node. The HSS may then receive an indication that a first service call session control function (S-CSCF) node is unresponsive. Upon receiving such an indication, the techniques may comprise determining, based on a user profile, that the first S-CSCF node is associated with the P-CSCF node; selecting, based on the information about the P-CSCF node, a second S-CSCF node to be associated with the P-CSCF node; and providing, by the HSS, at least a portion of the information about the P-CSCF node to the second S-CSCF node. The second S-CSCF node can then be configured to replace the first P-CSCF node using that information.