Domain Transfer Function for Emergency Session Continuity
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Solution Overview
Problem
There is a need to efficiently transfer emergency services sessions between circuit-switched and packet-based communication subsystems, ensuring continuity of emergency services as users move between different access points or subsystems, particularly for multimedia communications like 911 calls.
Innovation Solution
The implementation of a domain transfer function (DTF) within the multimedia subsystem, which anchors call signaling and provides location updates, enables seamless transfers between circuit-switched and packet-based subsystems by establishing and maintaining emergency services sessions, ensuring that calls are routed correctly and location information is updated during transfers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If emergency services sessions are transferred between circuit-switched and packet-based subsystems, then service continuity is improved, but system complexity increases
Solution Approach 1:
The patent introduces a Multimedia Subsystem (MS) as an intermediary between circuit-switched and packet-based subsystems. The MS provides domain transfer functions that enable seamless emergency services session transfers between disparate subsystems, maintaining service continuity while managing the complexity of inter-subsystem communication through a dedicated mediation layer.
Solution Approach 2:
The patent segments the emergency services session transfer process into distinct functional components: session initiation in the originating subsystem, session anchoring in the Multimedia Subsystem, and session completion in the target subsystem. This segmentation allows each subsystem to handle specific aspects of the transfer independently, reducing overall system complexity while ensuring reliable service continuity.
2Productivity
If domain transfer function anchors all call signaling, then transfer efficiency is improved, but signaling path length increases
Solution Approach 1:
The domain transfer function performs preliminary actions by pre-establishing session anchors and preparing transfer pathways before actual emergency services sessions need to be transferred. This includes pre-configuring the Multimedia Subsystem to handle inter-subsystem signaling, which streamlines subsequent transfers and improves efficiency despite the extended signaling path.
Data Source
AI summary
Methods and nodes for coordinating communication sessions are described herein. A method includes providing, by a control system, a signaling anchor point at a domain transfer function in a visited multimedia subsystem for an access signaling leg and a remote access signaling leg for a communication session between a user element and a public service access point and coordinating call signaling for the communication session via the access signaling leg and the remote signaling leg.