Method of data transfer in mobile and fixed telecommunications systems

• US 20050154774A1
• Filed: 03/26/2003
• Published: 07/14/2005
• Est. Priority Date: 03/28/2002
• Status: Active Grant

• Current Assignee: British Telecommunications PLC (BT Group PLC)
• Original Assignee: British Telecommunications PLC (BT Group PLC)
• Inventors: Giaffreda, Raffaele, Hodgkinson, Terence G
• Granted Patent: US 7,305,474 B2
• Time in Patent Office: Days
• US Class Current: 709/200
• CPC Class Codes: H04L 67/04 specially adapted for terminals or networks with limited capabilities; specially adapted for terminal portability
• CPC Class Codes: H04L 67/14 Session management for real-time applications in data packet communications networks H04L65/1066
• CPC Class Codes: H04L 67/146 Markers for unambiguous identification of a particular session, e.g. session cookie or URL-encoding
• CPC Class Codes: H04L 67/148 Migration or transfer of sessions
• CPC Class Codes: H04L 67/63 Routing a service request depending on the request content or context
• CPC Class Codes: H04W 4/18 Information format or content conversion, e.g. adaptation by the network of the transmitted or received information for the purpose of wireless delivery to users or terminals
• 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]
• CPC Class Codes: H04W 80/10 adapted for application session management, e.g. SIP [Session Initiation Protocol] connection management H04W76/00; arrangements for session management H04L67/14
• CPC Class Codes: H04W 88/04 adapted for relaying to or from another terminal or user
• CPC Class Codes: H04W 88/08 Access point devices

Abstract

The present invention relates to a method of data transfer between mobile or fixed end devices connected to respective base stations. The method includes the steps of selecting a first session identifier (session ID) from a first array for sessions originating from an initiating end device, transferring data as a plurality of packets each of which contains the first session ID to a remote end device connected to a remote base station, the remote base station being configured to: allocate a second session ID from a second array, map to one another the said first and second session IDs, and, a forward the said second session ID to the remote end device. In this way, the mapping between session IDs need not be stored in the end devices, allowing for a session to be handed over from one end device to another end device where both end devices are connected to the same base station.

Claims

1. A method of communication between end devices connected to a telecommunications network, the network comprising a local network access point to which an initiating end device is connected, and a remote network access point to which a remote end device is connected

the method comprising:

selecting, a first session identifier (session ID) from a first array comprising at least one assignable session ID;

storing first session ID at the network access point;

forwarding, from the initiating end device to the local network access point, a remote end device identifier, indicative of the identity of a remote end device with which the initiating end device is to communicate;

updating an initiating end device table with the remote end device identifier and with the first session ID; and

transferring data as a plurality of packets each of which contains the first session ID;

wherein the method further comprises;

sending the first session ID along with an identification of the said remote end device to the said remote network access point;

allocating at the said remote network access point, a second session ID from a second array comprising at least one assignable session ID;

updating a remote network access point table with the allocated second session ID such that the said first and second session IDs are mapped to one another;

and

forwarding the said second session ID to the remote end device;

the step of transferring data as a plurality of packets further comprising;

transferring each packet between the initiating end device and the remote network access point via the local network access point along with the said first session ID, and transferring each said packet between the remote fixed access device and the remote end device using the mapping of the said first to the said second session ID.

16. The method of claim 1, wherein the remote end device identifier forwarded from the initiating device is in a first format, the method further comprising resolving the remote end device identifier into a second format.

18. The method of claim 1, further comprising, upon termination of a session, resetting or removing the information held in each table regarding that now terminated session.

19. The method of claim 18, wherein the step of resetting or removing the information is carried out after a predetermined time out period.

25. The method of claim 1, further comprising transmitting an indicator of the data type between the end devices.

26. The method of claim 25, wherein the data type indicator forms a part of a header for each of the said packets to be transferred.

27. The method of claim 25, further comprising selecting a medium in which the transferred data is to be handled, the selection taking place on the basis of the data type indicator.

2. A method of communication between end devices connected to a telecommunications network, the network comprising a local network access point having a plurality of assignable communications channels, the method comprising:

allocating a communications channel to each of the end devices connected to the network;

maintaining, at the local network access point, a local network access point table which cross-references each allocated channel with an identification of the end device to which it is allocated;

maintaining, at each end device to which a communication channel has been allocated, an end device table which contains the allocated communications channel identifier for that end device;

selecting, at an initiating end device, a first session identifier (session ID) from a first array comprising at least one assignable session ID;

adding the first session ID to the end device table of the initiating end device;

forwarding the first session ID from the initiating end device to the network access point;

forwarding, from the initiating end device to the local network access point, a remote end device identifier, indicative of the identity of a remote end device with which the initiating end device is to communicate;

updating the initiating end device table with the remote end device identifier and with the first session ID;

returning a communication commencement request to the initiating end device; and

transferring data as a plurality of packets each of which contains the first session ID, between the said initiating end device and the said remote end device via the local network access point.

3. The method of claim 2, in which the telecommunications network further comprises a remote network access point to which the remote end device is connected, the remote network access point also having a plurality of assignable channels, the method further comprising:

allocating a communications channel for the remote network access point to each of the end devices connected to the network via the said remote network access point; and

maintaining, at the remote network access point, a remote network access point table which cross-references the channels allocated to these devices connected to the network via the said remote network access point with a corresponding end device identifier.

4. The method of claim 3, wherein the remote end device is Internet Protocol (IP) enabled, the local and remote access point tables being maintained with cross references for each allocated channel with a corresponding IP address assigned by the local and remote network access point tables respectively, and wherein the remote end device identifier is an IP address assigned by the said remote network access point, the method further comprising:

forwarding data to be transferred from the initiating end device to the local network access point as a plurality of session packets each including the said first session ID;

encapsulating, at the local network access point the data within each session packet into a transport layer packet such as TCP or UDP;

inserting the first session ID into each said transport layer packet;

encapsulating each transport layer packet into an Internet Protocol packet; and

forwarding each IP packet to the said remote network access point for transmission to the said remote end device.

5. The method of claim 4, further comprising:

searching the remote network access point table of the remote network access point upon receipt of an IP packet; and

forwarding that IP packet to the remote end device as is, if the said searching step indicates that the IP address in the IP packet is not found in the list of IP addresses held by the said remote network access point table.

6. The method of claim 4, further comprising:

searching the remote network access point table of the remote network access point upon receipt of an IP packet;

transferring the data within the IP packet received at the said remote network access point into a session packet when the said searching step determines that the IP address in the received IP packet is found in the list of IP addresses held by the said remote network access point table; and

forwarding the session packet to the remote end device on the basis of the IP address of the remote end device located in the remote network access point table.

7. The method of claim 3, wherein the remote end device is or is not IP enabled, the local and remote access point tables being maintained with cross-references for each allocated channel with a corresponding IP address assigned by the local and remote network access point tables respectively, and wherein the remote end device identifier is an IP address assigned by the said remote network access point, the method further comprising:

sending the first session ID along with an identification of the said remote end device to the said remote network access point;

allocating at the said remote network access point, a second session ID from a second array comprising at least one assignable session ID;

updating the remote network access point table with the allocated second session ID such that the said first and second session IDs are mapped to one another; and

forwarding the said second session ID to the remote end device;

the step of transferring data as a plurality of packets further comprising;

transferring each packet between the initiating end device and the remote network access point via the local network access point along with the said first session ID, and transferring each said packet between the remote fixed access device and the remote end device using the mapping of the said first to the said second session ID.

8. The method of claim 7, wherein each packet is transferred between the remote network access point and the initiating end device, via the said first end device, as a session packet including the said first session ID within a header portion of each said session packet, and between the said remote end device and the remote network access point as a session packet including the said second session ID within the said header portion thereof, the method further comprising:

replacing, at the remote network access point, the said first session ID in the said session packets with the mapped second session ID when the said session packets have arrived from the said initiating end device.

9. The method of claim 3, wherein the step of sending the first session ID and the identification of the said remote end device further comprises sending an application identifier which identifies an application to be employed by the said remote end device, the method further comprising:

ascertaining, at the remote network access point and on the basis of the received application identifier, whether the remote end device is capable of accepting the request to employ the said application; and

forwarding data from the initiating device for use by the said application in the event that the remote end device is capable of accepting the request.

10. The method of claim 9, wherein the said remote network access point table maintains a list of available applications for the said remote end device, the step of ascertaining whether the remote end device is capable of accepting the request comprising determining from the said remote network access point table whether the received application identifier is compatible with the said list of available applications for the said remote end device.

11. The method of claim 9, wherein the said application identifier is a well known port number.

12. The method of claim 9, further comprising:

maintaining, in the remote network access point table, a list of the number of parallel sessions supportable by the said remote end device along with a list of the number of those parallel sessions already taking place, and

forwarding the said data in the event that the remote end device has at least one available session as determined from the said remote network access point table.

13. The method of claim 9, further comprising:

maintaining, in the remote end device table, a list of the number of parallel sessions supportable by the said remote end device along with a list of the number of those parallel sessions already taking place; and

forwarding the said list within the said remote end device table to the remote network access point table at least when the said remote end device table is updated in this respect.

14. The method of claim 7, wherein the step of returning a communication commencement request to the initiating end device is initiated from the said remote end device.

15. The method of claim 4, wherein the step of returning a communication commencement request to the initiating end device is initiated from the said remote network access point.

17. The method of claim 2, further comprising ascertaining whether the remote end device is IP enabled or not.

20. The method of claim 3, wherein the connection point of the remote end device is to be changed from a first remote network access point to a second, different remote network access point, the method further comprising:

allocating a new remote communications channel for communication between the remote end device and the second remote network access point, the new remote communications channel having an associated new remote communications channel identifier;

forwarding the new remote communications channel identifier from the second remote network access point to the first remote network access point;

returning, from the first remote network access point to the second remote network access point, the contents of the first remote network access point table, the new remote communications channel identifier being employed as a routing controller;

replacing the old remote communications channel identifier, received from the first remote network access point table, with the new remote communications channel identifier;

adding the contents of the first remote network access point, including the new remote communications channel identifier, to the second remote network access point table; and

transferring data between the initiating and remote end devices via the local network access point and the second remote network access point.

21. The method of claim 3, wherein the connection point of the initiating end device is to be changed from a first local network access point to a second local network access point, the method further comprising:

allocating a new local communications channel for communication between the initiating end device and the second local network access point, the new local communications channel having an associated new local communications channel identifier;

forwarding the new local communications channel identifier from the second local network access point to the first local network access point;

returning, from the first local network access point to the second local network access point, the contents of the first local network access point table, the new local communications channel identifier being employed as a routing controller;

replacing the old local communications channel identifier, received from the first local network access point table, with the new local communications channel identifier;

adding the contents of the first local network access point, including the new local communications channel identifier, to the second local network access point table; and

transferring data between the remote and initiating end devices via the remote network access point and the second local network access point.

22. The method of claim 20, wherein the data is removed from the first network access point table once it has been forwarded to the second network access point table.

23. The method of claim 3, wherein the data transfer destination is to be changed from a first remote end device to a second remote end device, the method further comprising:

forwarding a new device remote communications channel identifier for the said second remote end device to the remote network access point;

replacing the old device remote communications channel identifier with the new device remote communications channel identifier in the remote network access point table; and

transferring data between the second remote end device and the initiating device via the remote network access point and the local network access point.

24. The method of claim 23, further comprising:

detecting the geographical location of the first remote end device; and

forwarding the new device remote communications channel identifier to the remote network access point, to start handover to the second remote end device, only when the first remote end device is within a predefined range of the second remote end device.

28. A database for a network access point in a telecommunications network, comprising:

(a) a cross-reference between (i) one of a plurality of communications channels assigned for communication between the network access point and an end device, and (ii) a corresponding device identifier for that end device to which that communications channel is assigned;

(b) a first session identifier (session ID) received from a initiating end device and selected from one of a plurality of session IDs held by that end device; and

(c) a remote end device identifier indicative of the destination of data to be sent from the initiating end device;

the database being configured to permit routing of data packets containing the first session ID between the initiating and the remote end devices, via the network access point.

29. A local network access point for a telecommunications network, the local network access point comprising:

a plurality of communications channels at least some of which are assigned for communication with a corresponding plurality of end devices; and

a database under the control of the local network access point, the data base including;

(a) a cross-reference between the assigned communication channels and an identification of an end device to which that channel is allocated;

(b) a first session identifier (session ID) forwarded from an initiating end device and selected from one of a plurality of session IDs held by that end device; and

(c) a remote end device identifier indicative of the destination of data to be sent from the initiating end device

the local network access point being arranged to route packets of data, each containing the said session ID, in accordance with the contents of the said database.