Seamless IMS Connection Management for Service Continuity
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Solution Overview
Problem
Current agnostic Internet Protocol multimedia communication systems face disruptions in service continuity when IMS terminals change IP-CANs, leading to loss of sessions and subscriptions, and existing mobility solutions like Mobile IP do not support seamless handoffs or movement of specific dialogs and sessions.
Innovation Solution
Implement Seamless IMS Connections by allowing IMS terminals to establish new connections with minimal disruption, using IPsec Security Associations and SIP procedures to manage registration bindings and sessions across different IP connections, with features like Linger Timer for inactive connections to support break-before-make handover scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If IMS terminal changes IP-CAN to access different networks, then network accessibility and versatility are improved, but service continuity is disrupted and sessions are lost
Solution Approach 1:
The patent establishes a new IP connection before terminating the old one, maintaining registration bindings and active sessions on both connections simultaneously during the transition period. This preliminary establishment of the new connection ensures service continuity while enabling network versatility.
Solution Approach 2:
The patent uses registration bindings as an intermediary mechanism that can be maintained across multiple IP connections. By keeping these bindings active on both old and new connections during handover, the system mediates between network accessibility changes and service continuity requirements.
2Speed
If Mobile IP is used to support mobility, then network layer mobility is improved, but application layer session mobility cannot be achieved
Solution Approach 1:
The patent extends mobility from the network layer (Mobile IP) to the application layer (IMS) by maintaining registration bindings at the SIP level. This dimensional extension allows sessions to be moved between different IP connections while keeping the underlying Mobile IP infrastructure intact.
Solution Approach 2:
The patent separates the mobility management into distinct components: network layer mobility handled by Mobile IP and application layer session mobility handled by maintaining multiple registration bindings. This segmentation allows each layer to operate independently and effectively.
3Ease of operation
If all dialogs and sessions are moved together, then mobility management is simplified, but selective session mobility cannot be achieved
Solution Approach 1:
The patent enables different quality states for different sessions by allowing selective maintenance of registration bindings. Each active session can be independently associated with specific IP connections, allowing selective mobility where only certain sessions are moved while others remain on the original connection.
Solution Approach 2:
The patent makes the session-to-connection mapping dynamic rather than static. Registration bindings can be selectively maintained or released on different IP connections based on session requirements, enabling flexible and selective session mobility rather than forcing all-or-nothing movement.
4Adaptability or versatility
If IP address changes during IMS connection, then network flexibility is improved, but authentication and security associations must be re-established
Solution Approach 1:
The patent maintains registration bindings and IPsec Security Associations continuously across IP address changes by keeping them active on both old and new connections during the transition. This continuity eliminates the need to re-authenticate and re-establish security associations, saving time while maintaining network flexibility.
Solution Approach 2:
The patent prepares for IP address changes by maintaining redundant registration bindings and security associations in advance on multiple IP connections. This beforehand cushioning ensures that when an IP address change occurs, the terminal can immediately use the pre-established bindings without interruption or re-authentication.
Data Source
AI summary
State machine diagram (300) illustrates inactive connection (303) management wherein all bindings are deregistered, but active sessions remain. The mobile station may, re-register the connection (309), to stop the Linger Timer (305) and return the connection to the active state (303) before timeout, or otherwise before the inactive connection is terminated. Otherwise, the Linger Timer may be stopped when the last active session is moved to a different connection, or released (311). If the Linger Timer times out (315), any active sessions will be released without the explicit action of the mobile station. In the active state (303), if all bindings are deregistered and no active sessions are present, the connection may be terminated immediately as in (313), without invoking the Linger Timer. Thus, the mobile station has an opportunity to take action regarding remaining sessions, such as releasing or refreshing on a different but active connection.