Session Continuity Management for IMS Conference Calls During SRVCC Handover
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Solution Overview
Problem
The existing 3GPP specifications lack clear definitions for managing call continuity when a user equipment (UE) handovers from LTE coverage to UMTS/GSM coverage, leading to unexpected call drops and unsynchronized call states due to inconsistent UE implementations, especially in scenarios involving multiple IMS ongoing sessions and conference calls.
Innovation Solution
A method is provided to manage call continuity by monitoring ongoing sessions in an IMS network, detecting network-switching events, determining which sessions to release or transfer to a circuit-switched CS network, and performing a session transfer procedure, including mapping call states and assigning transaction identifiers during a Single Radio Voice Call Continuity (SRVCC) handover.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple IMS ongoing sessions are established without clear management rules, then service versatility is improved, but call continuity reliability deteriorates due to unexpected call drops and unsynchronized call states during handover
Solution Approach 1:
The patent applies preliminary action by establishing clear session management rules and state mapping definitions before handover occurs. The specification pre-defines how multiple IMS sessions should be handled during SRVCC handover, including which sessions to transfer and which to release, thereby preventing call drops and state desynchronization before they can occur.
Solution Approach 2:
The patent applies parameter changes by defining specific parameters for session management during handover, including session states (active, held, released), call states (multiparty, single-party), and transaction identifiers. These parameter definitions enable consistent UE implementation and reliable session continuity across network transitions.
2Ease of operation
If UE implementations follow inconsistent interpretations of existing specifications, then ease of operation is improved for individual implementations, but manufacturing precision deteriorates due to lack of consistent agreement in 3GPP specification
Solution Approach 1:
The patent applies homogeneity by providing unified, consistent definitions for session management across all UE implementations. The specification establishes homogeneous rules for handling multiple IMS sessions during handover, ensuring that all UEs interpret and implement the protocol in the same way, thereby achieving manufacturing precision while maintaining ease of operation through clear guidance.
Solution Approach 2:
The patent applies segmentation by breaking down the complex session management process into distinct, manageable segments: session monitoring, handover detection, session determination (which sessions to transfer/release), and session transfer execution. This segmentation provides clear implementation guidelines while maintaining overall system consistency.
3Reliability
If clear session management rules are established for multiple IMS sessions during handover, then call continuity reliability is improved, but device complexity increases due to additional monitoring and determination procedures
Solution Approach 1:
The patent applies self-service by enabling the UE to autonomously monitor its own IMS sessions, detect handover events, determine which sessions to transfer or release, and execute the session transfer procedure without requiring complex external coordination. The UE independently manages its session state based on the standardized rules, reducing overall system complexity while maintaining high reliability.
Data Source
AI summary
A method to manage call continuity in a network environment including a circuit-switched network and an IP multimedia subsystem (IMS) network is provided. A UE monitors one or more ongoing sessions in an IMS network, and the ongoing sessions contain at least one conference call. The UE detects a network-switching event for the UE to switch from the IMS network to a circuit-switched CS network. The UE then determines the one or more ongoing sessions within the IMS network to be released or transferred to the CS network. Finally, the UE performs a session transfer procedure for transferring the determined sessions.