FAST HANDOVER USING SIP

• US 20090177785A1
• Filed: 03/30/2007
• Published: 07/09/2009
• Est. Priority Date: 04/03/2006
• Status: Active Grant

• Current Assignee: British Telecommunications PLC (BT Group PLC)
• Original Assignee: British Telecommunications PLC (BT Group PLC)
• Inventors: Reid, Gidon M., Jover Aparicio, Fernando, Singh, Devinder
• Granted Patent: US 8,032,656 B2
• Time in Patent Office: Days
• US Class Current: 709/228
• CPC Class Codes: H04L 61/00 Network arrangements, protocols or services for addressing or naming
• CPC Class Codes: H04L 65/1101 Session protocols
• CPC Class Codes: H04L 65/1104 Session initiation protocol [SIP]
• CPC Class Codes: H04L 65/65 Network streaming protocols, e.g. real-time transport protocol [RTP] or real-time control protocol [RTCP]
• CPC Class Codes: H04W 8/26 Network addressing or numbering for mobility support
• CPC Class Codes: H04W 80/04 Network layer protocols, e.g. mobile IP [Internet Protocol]

Abstract

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.

Claims

1. 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:

(i) mapping at the proxy server the fixed address with a dynamic network address allocated to the first user agent;

(ii) sending a request by the first user agent to the second user agent for a data stream;

(iii) 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;

(iv) 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

(v) 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.

2. A method as claimed in claim 1, wherein the dynamic network address is an IP address.

3. A method as claimed in claim 1, wherein the new dynamic network address results from the first user agent moving from a first subnet to a second subnet.

4. A method as claimed in claim 1, wherein the new dynamic network address results from a change in location.

5. A method as claimed in claim 1, wherein each message comprises a message header and message body, and the data stream is embedded in the message body and the fixed address is in the message header.

6. A method as claimed in claim 1 wherein the request comprises a call identifier and each generated message comprises the same call identifier.

7. A method as claimed in claim 1 wherein the first user agent parses each message from the proxy server in dependence on the call identifier in each message.

8. A method as claimed in claim 1 wherein each generated message includes a sequence number to indicate a preferred order for the message to be processed by the first user agent.

9. A method according to claim 1, wherein the first user agent maintains the first dynamic network address until the second dynamic network address is allocated and registered with the proxy server.

10. A method according to claim 1, wherein the first and second user agents are SIP devices.

11. A method according to claim 1, wherein the fixed network address is a SIP universal resource indicator.