Session Continuity via Handover Anchor Functions
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Solution Overview
Problem
Existing solutions for maintaining session continuity in IP multimedia communication systems, such as IMS and NGN, face challenges when a user changes access addresses, access technologies, or terminals, leading to session interruptions and quality issues due to lack of IP address preservation and inadequate handling of bandwidth differences and media attribute modifications.
Innovation Solution
The implementation of a method and system using Handover Source Function (HOSF) and Handover Destination Function (HODF) to establish new session connections upon detecting handover conditions, ensuring seamless session continuity by swapping connections on the service layer and managing media stream modifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a user changes access address or access technology during a session, then the user can utilize different access networks, but the session continuity is interrupted and quality deteriorates
Solution Approach 1:
The patent introduces a session border controller (SBC) as an intermediary entity that mediates between different access networks and the core session management system. The SBC maintains session state information and coordinates handover procedures, enabling seamless transitions between access technologies while preserving session continuity. This intermediary layer shields the core network from access network changes and ensures reliable session maintenance during transitions.
Solution Approach 2:
The patent implements preliminary registration and pre-establishment of session parameters before actual handover occurs. The terminal performs proactive session parameter negotiation and pre-configures handover policies, allowing the network to prepare resource allocation and routing paths in advance. This preliminary action ensures that when handover is triggered, the session can transition smoothly without interruption or quality degradation.
2Adaptability or versatility
If IP address changes occur during handover, then the terminal can access different networks, but media attribute modification and bandwidth differences cause quality issues
Solution Approach 1:
The patent implements dynamic parameter adaptation mechanisms that automatically adjust media attributes based on the target access network characteristics. When handover is detected, the system negotiates and modifies parameters such as codec selection, bitrate, packet size, and timing parameters to match the capabilities of the new access network. This parameter adaptation ensures media quality consistency despite IP address changes and bandwidth variations across different networks.
Solution Approach 2:
The patent employs session parameter copying and template matching approaches where successful session configurations from one access network are replicated and adapted for use in another network. The system maintains parameter templates for different access network types and copies appropriate parameters during handover, ensuring media attribute consistency while accounting for network-specific characteristics.
Data Source
AI summary
A method and a system for maintaining session continuity, in which the system includes a Handover Source Function (HOSF), a Handover Destination Function (HODF), a Handover Anchor Function-Control Plane (HOAF-CP) and a Handover Anchor Function-User Plane (HOAF-UP). The method includes a first user establishing a connection through the HOSF with the HOAF-CP and the HOAF-UP which correspond to a second user, so as to establish a session with the second user. The method further includes that, during session handover, the HODF that corresponds to the HOSF establishing another connection with the HOAF-CP and HOAF-UP though which the first user continues the session with the second user, so as to maintain the session continuity. When access address or access technology of the terminal changes, or even the terminal changes during a session, the method and the system can logically replace the connection before the handover with a new connection to ensure the session continuity.