S-CSCF Traffic Redistribution via Explicit Reselection Instructions
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Solution Overview
Problem
The existing IMS Restoration Procedures are not well-suited for dynamic redistribution of traffic within the IP Multimedia Subsystem, leading to uneven traffic distribution and service disruptions when users are transferred between Serving Call Session Control Functions (S-CSCFs).
Innovation Solution
A method and apparatus for smoothly transferring IMS users between S-CSCFs by sending explicit instructions from one S-CSCF to another, utilizing mechanisms such as Reg-Event, Unsolicited Notification, or Transfer Triggered on Non-Register Requests, to facilitate seamless reselection and minimize service interruptions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing IMS Restoration Procedures are used for user transfer between S-CSCFs, then user registration can be restored after S-CSCF failure, but traffic distribution becomes uneven and service disruptions occur during user transfer
Solution Approach 1:
The patent implements dynamic S-CSCF reselection by allowing the I-CSCF to dynamically choose a different S-CSCF based on current network conditions and load, rather than statically binding users to specific S-CSCFs. This enables flexible traffic redistribution while maintaining user service continuity
Solution Approach 2:
The patent introduces a feedback mechanism where the I-CSCF receives information about S-CSCF availability and user service status, then uses this feedback to make intelligent reselection decisions. This ensures that user transfers are performed only when appropriate, avoiding unnecessary service disruptions
2Productivity
If S-CSCF reselection is triggered for user transfer, then traffic can be redistributed across the network, but service interruptions occur during the transfer process
Solution Approach 1:
The patent performs preliminary actions by having the I-CSCF evaluate S-CSCF availability and user service status before triggering reselection. This preliminary assessment ensures that reselection is only initiated when it will improve traffic distribution without causing service disruption
Solution Approach 2:
The I-CSCF acts as an intermediary between the user equipment and the S-CSCF pool, mediating the transfer process by selecting appropriate target S-CSCFs and coordinating the handover. This intermediary role smooths the transfer process and minimizes service interruptions
3Productivity
If explicit S-CSCF selection instructions are sent to I-CSCF, then controlled traffic redistribution is achieved, but network signaling complexity increases
Solution Approach 1:
The patent extends the existing Reg-Event mechanism to serve multiple purposes: both maintaining user registration state and enabling controlled S-CSCF reselection. This multi-functionality avoids creating separate complex signaling paths while achieving traffic redistribution goals
Data Source
AI summary
A method of handling traffic within an IP Multimedia Subsystem, IMS, network. The method comprises registering an IMS user with a first Serving Call Session Control Function, S-CSCF, of the IMS network. Subsequently, at the first S-CSCF, a decision is made or instruction received to transfer said user to an alternative, second S-CSCF within the IMS network. A notification is sent from said first S-CSCF to a further IMS node, the notification including an explicit instruction to select a second S-CSCF and, upon receipt of said notification at the further IMS node, an S-CSCF reselection initiated for the user in order to select a second S-CSCF.