HSS Deregistration Reason for Fixed-Line UE Location Updates
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Solution Overview
Problem
Fixed-line user equipment (UE) experiences service disruption due to incorrect deregistration reasons sent by the Home Subscriber Server (HSS) to the Serving Call Session Control Function (S-CSCF) during location updates, leading to permanent termination and loss of network registration.
Innovation Solution
The HSS sends an accurate deregistration reason indicating a 'REFLOC_CHANGE' instead of 'PERMANENT_TERMINATION', allowing the S-CSCF to use 'event=deactivated' instead of 'event=rejected', enabling the fixed-line UE to re-register with the network and update its reference location information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the HSS sends a deregistration reason indicating 'PERMANENT_TERMINATION' during location updates, then the network processes the location update, but the fixed-line UE loses network registration and experiences service disruption
Solution Approach 1:
The patent changes the deregistration reason parameter from 'PERMANENT_TERMINATION' to 'REFLOC_CHANGE' (reference location change). This parameter change fundamentally alters the UE's behavior: instead of treating the location update as a permanent termination event, the UE recognizes it as a reference location update and maintains its network registration, thereby preventing service disruption while still processing the location update correctly.
2Reliability
If the S-CSCF uses 'event=rejected' during location updates, then the network processes the update, but the fixed-line UE cannot re-register with the network
Solution Approach 1:
The patent changes the event parameter from 'event=rejected' to 'event=deactivated'. This parameter change is crucial because 'deactivated' allows the UE to initiate re-registration procedures, while 'rejected' would permanently block re-registration. The S-CSCF sends the deactivated event in the SIP NOTIFY message to the UE, enabling the UE to understand that it should re-register rather than being permanently rejected, thus maintaining service continuity and re-registration capability.
3Productivity
If the HSS sends incorrect deregistration reasons during location updates, then the network processes the update, but the fixed-line UE experiences permanent termination
Solution Approach 1:
The patent implements feedback mechanisms where the HSS, S-CSCF, and UE exchange information about the correct deregistration reason. The HSS provides feedback to the S-CSCF about the accurate reason (REFLOC_CHANGE), and the S-CSCF provides feedback to the UE through SIP NOTIFY messages with the correct event type. This feedback loop ensures that all network elements have consistent understanding of the location update nature, preventing incorrect permanent termination while maintaining efficient processing.
Data Source
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AI summary
The disclosed apparatus comprises means for performing storing location information of one or more fixed-line user equipment operating in an internet protocol multimedia subsystem. In response to an update of location information at the apparatus for one or more of the fixed-line user equipment,the apparatus comprises means for sending a message to a serving call state control function serving the one or more fixed-line user equipment. The message indicates a location update of the one or more fixed- line user equipment whose location information has been updated at the apparatus.