SIP Server Session Continuity During Mobile Gateway Handover
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Solution Overview
Problem
Current methods fail to ensure continuous management of communication sessions for fourth-generation mobile terminals during macro-mobility, leading to risks of service interruption when mobile terminals move out of the coverage area of the initial base station and switch to a different access gateway.
Innovation Solution
A method that involves transmitting an alert message to a new SIP server when a mobile terminal changes access gateways, allowing the new server to request the call context from the previous server and send an invitation message with connection parameters to the terminal, enabling seamless session management without requiring modifications to the SIP clients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If centralized session management is used with a single SIP server, then session management is simplified, but service continuity is lost during macro-mobility events
Solution Approach 1:
The centralized SIP server is segmented into multiple distributed SIP servers (first SIP server, second SIP server). Each server can independently manage communication sessions, allowing the system to maintain service continuity when a terminal moves between access gateways by transferring session management to a different server.
Solution Approach 2:
An alert message mechanism acts as an intermediary between access gateways and SIP servers. When a terminal changes access gateway, the new gateway sends an alert message to trigger session context transfer between SIP servers, ensuring seamless handover without terminal involvement.
2Reliability
If session context is transferred between SIP servers during macro-mobility, then service continuity is maintained, but network signaling overhead increases
Solution Approach 1:
The session context transfer mechanism extracts only the essential session management information (session parameters, terminal identification) from the complete session data. This selective transfer minimizes signaling overhead while maintaining service continuity, avoiding unnecessary data transmission.
3Reliability
If multiple SIP servers are distributed across the network, then service continuity during macro-mobility is improved, but system complexity increases
Solution Approach 1:
Each distributed SIP server is designed with universal functionality to manage communication sessions independently. Any SIP server can take over session management for a moving terminal, eliminating the need for complex server-specific configurations and simplifying the overall system architecture despite the distributed nature.
4Productivity
If session management is tied to a specific access gateway, then local optimization is achieved, but macro-mobility continuity is compromised
Solution Approach 1:
The session management system transitions from a static gateway-bound model to a dynamic server-based model. Session context can be dynamically transferred between SIP servers based on terminal mobility, allowing the system to adapt to changing network conditions while maintaining local management efficiency through the alert message trigger mechanism.
Data Source
Figure 1a
Figure 1b
Figure 2~3
AI summary
The invention relates to a method for ensuring continuity during the management of communication sessions operated from a fourth-generation mobile terminal (130) communicating on an IP network, said network including at least one radio network (110) provided with a plurality of base stations (111) with which said terminal (130) is capable of communicating, said radio network (110) being connected by means of access gateways (113, 113b, 113c) to an interconnect network (120) provided with application servers (150a, 150b, 150c) for managing communication sessions, the sessions of a mobile terminal (130) being managed by means of one of said servers (150a, 150b, 150c), wherein the method comprises at least the following steps: during a movement of the mobile terminal (130) resulting in a change of the access gateway, the new gateway (113b) transmits an alarm message to a new server for managing the communication sessions (150b); the new management server (150b) issues an interrogation request to at least one of the session management servers (150a, 150c) of said interconnect network different from said new server in order to recover the call context from the initial server (150a) that managed the session before the movement of the terminal (130); the new session management server (150b) transmits to the mobile terminal (130) an invitation along with the connection parameters such that said terminal can be connected to the new server (150b).