SIP Proxy Address Mapping for Seamless Handover
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Solution Overview
Problem
Existing methods for handover of active data sessions in mobile communications networks, such as Wi-Fi, result in interruptions due to the need to terminate and restart RTP sessions when a user moves between IP subnets, causing delays and data loss in real-time services like voice calls or video streaming.
Innovation Solution
A method utilizing modified SIP messages to carry data streams, where the SIP proxy server maps a fixed address to a dynamic network address, allowing seamless handover by replacing the mapped address with a new one when the user agent changes IP addresses, eliminating the need for new SIP INVITE messages and maintaining continuous data transfer without altering the content server's processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional SIP handover is used to notify the data server of a new IP address, then the user device can maintain connectivity, but handover latency increases and real-time services experience interruptions
Solution Approach 1:
The patent merges signaling data and transport data into a single data stream transmitted over one RTP session. Instead of separating control messages (SIP INVITE) from media data, both are multiplexed together, eliminating the need for separate session establishment procedures during handover and reducing latency
Solution Approach 2:
The system performs preliminary actions by pre-establishing a single RTP session that can carry both signaling and transport data. This preparatory configuration allows the data stream to be immediately redirected to the new IP address without requiring additional session setup, thus reducing handover latency
2Reliability
If a new RTP session is created after IP address change, then data can be routed to the new address, but data loss occurs during the transition period
Solution Approach 1:
The patent maintains continuity of the RTP session across IP address changes. The single persistent session allows data to flow continuously without interruption, as the session parameters remain valid and the data stream can be seamlessly redirected to the new address without termination or re-establishment
Solution Approach 2:
By combining signaling and transport data into one continuous data stream over a single RTP session, the system ensures uninterrupted data flow during handover. The merged stream maintains its integrity and can be redirected atomically, preventing data loss that would occur with separate session management
3Reliability
If separate SIP INVITE messages are sent for each data stream, then the data server can route data correctly, but device complexity and processing overhead increase
Solution Approach 1:
The patent creates a universal data stream that can carry multiple types of data (signaling and transport) simultaneously. This multi-functional approach eliminates the need for separate SIP INVITE messages for each data type, reducing processing overhead while maintaining reliable routing through a single multiplexed channel
Data Source
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AI summary
A method of handling a data stream during a handover in a communications network comprising a first user agent having a fixed address, a proxy server and a second user agent, said method comprising the steps of: mapping at the proxy server the fixed address with a dynamic network address allocated to the first user agent; sending a request by the first user agent to the second user agent for a data stream; generating by the second user agent in response to the request a plurality of messages each comprising part of the data stream requested and the fixed address of the first user agent, wherein the message is a session initiation protocol message, and sending the messages to the proxy server; receiving the messages at the proxy server and determining the mapped dynamic network address corresponding to the fixed address in the message, and forwarding the messages to the determined dynamic network address; and when the first user agent is allocated a new dynamic network address, replacing by the proxy server the mapped dynamic network address with the new dynamic network address and forwarding the received messages to the new dynamic network address.