Method for performing inter-system handovers in a mobile communication system

• US 7,640,036 B2
• Filed: 08/11/2005
• Issued: 12/29/2009
• Est. Priority Date: 05/11/2005
• Status: Expired due to Fees

• Current Assignee: RPX Corporation
• Original Assignee: Nokia Solutions and Networks US LLC (Nokia Corporation)
• Inventors: Kallio, Juha
• Primary Examiner(s): WASHINGTON, ERIKA ALISE
• Application Number:
  US11/201,123
• Publication Number:
  US 20060258358A1
• Time in Patent Office: 1,601 Days
• Field of Search: None
• US Class Current: 455/552.1
• CPC Class Codes: H04L 65/1016 IP multimedia subsystem [IMS]
• CPC Class Codes: H04L 65/1043 Gateway controllers, e.g. media gateway control protocol [MGCP] controllers
• CPC Class Codes: H04L 65/1095 Inter-network session transfer or sharing
• CPC Class Codes: H04W 36/0066 of control information between different types of networks in order to establish a new radio link in the target network
• CPC Class Codes: H04W 72/04 Wireless resource allocation
• CPC Class Codes: H04W 76/10 Connection setup
• CPC Class Codes: H04W 76/30 Connection release
• CPC Class Codes: H04W 80/00 Wireless network protocols or protocol adaptations to wireless operation
• 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 88/06 adapted for operation in multiple networks or having at least two operational modes, e.g. multi-mode terminals
• CPC Class Codes: H04W 88/16 Gateway arrangements

Abstract

The invention relates to a method for performing inter-system handovers in a communication system comprising at least a mobile station, a call state control function, a first and a second call control node, a first and a second media gateway and a radio network node. The handover is achieved by way of connecting a call control node to a call state control function. The call control node allocates a media gateway for the session established. The session media bearers are routed via the media gateway. The call control node acts as an anchor node for the handover. As the mobile station moves to a new cell a media bearer is established to the media gateway from the mobile station via the new cell.

Claims

1. A method, comprising:

receiving a session set-up message from a mobile station to a call state control function;

determining inter-system handover support of the mobile station in said call state control function;

providing said session set-up message to a first call control node in response to said inter-system handover support of the mobile station;

requesting an allocation of a first media gateway from said first call control node;

receiving a handover request to said first call control node from said mobile station via said call state control function;

determining in said first call control node an identity of a second call control node based on cell information in said handover request;

sending the handover request from said first call control node to said second call control node;

receiving a handover number to said first call control node from said second call control node in response to said handover request;

routing a handover session from said first call control node to said second call control node using said handover number;

receiving an answer message to said first call control node from said second call control node;

receiving a handover completion message to said first call control node from said call state control function; and

requesting a removing of at least one packet switched media bearer from said media gateway.

2. The method according to claim 1, the method further comprising:

receiving a registration message from said mobile station to said call state control function;

fetching subscriber data associated with said mobile station from a home subscriber server to said call state control function;

determining in said call state control function whether said registration message must be provided to said first call control node;

providing said registration message to said first call control node;

determining in said first call control node whether said mobile station supports inter-system handover;

performing location update procedure between said first call control node and a home location register; and

said first call control node acknowledging said registration message to said mobile station via said call state control function.

3. The method according to claim 1, the method further comprising:

said mobile station determining the availability of an unlicensed radio band;

said mobile station sending a session set-up message via said unlicensed radio band;

said mobile station determining the availability of a licensed radio band and cell information associated with said licensed radio band; and

said mobile station performing decision on handover to said licensed radio band.

4. The method according to claim 3, wherein said licensed radio band is used by at least one of the global system of mobile communications, the general packet radio system and the universal mobile telecommunication system.

5. The method according to claim 3, wherein said unlicensed radio band is used by at least one of a wireless local area network, a Bluetooth™

base transceiver station and a short range point-to-point radio base transceiver station.

6. The method according to claim 1, wherein said first call control node and said second call control node are mobile switching center servers.

7. The method according to claim 1, wherein said at least one packet switched media bearer is transmitted over Internet Protocol between said mobile station and said media gateway.

8. The method according to claim 1, wherein radio resources used by said mobile station comprise at least one radio channel.

9. The method according to claim 8, wherein each of said at least one radio channel comprises at least one of a carrier frequency, a timeslot, a spreading code and an orthogonal frequency division multiplexing sub-carrier.

10. The method according to claim 1, wherein said mobile station comprises a session initiation protocol user agent.

11. The method according to claim 1, wherein a communication system of the call control nodes comprises an IP multimedia subsystem.

12. A system comprising:

a call state control function node configured to receive a session set-up message from a mobile station, to determine inter-system handover support of the mobile station, to provide said session set-up message to a first call control node in response to said inter-system handover support of said mobile station, and wherein said first call control node is configured to request an allocation of a first media gateway,

receive a handover request from said mobile station via said call state control function, to determine an identity of a second call control node based on cell information in said handover request,

send the handover request to said second call control node,

receive a handover number from said second call control node in response to said handover request,

route a handover session from said first call control node to said second call

control node using said handover number,

receive an answer message from said second call control node,

receive a handover completion message from said call state control function, and

request a removing of at least one packet switched media bearer from said media gateway.

13. The system according to claim 12, wherein said call state control function is further configured to receive a registration message from said mobile station, to fetch subscriber data associated with said mobile station from a home subscriber server, to determine whether said registration message must be provided to said first call control node and to provide said registration message to said first call control node, and

said first call control node is configured to determine whether said mobile station supports inter-system handover, to perform a location update procedure towards a home location register and to acknowledge said registration message to said mobile station via said call state control function.

14. The system according to claim 12, wherein said mobile station is configured to determine the availability of an unlicensed radio band, to send a session set-up message via said unlicensed radio band, to determine the availability of a licensed radio band and cell information associated with said licensed radio band and to perform decision on handover to said licensed radio band.

15. The system according to claim 14, wherein a radio network node is configured to be connected to a base transceiver station, said base transceiver station being configured to use said licensed band.

16. The system according to claim 12, the system further comprising:

a second base transceiver station configured to communicate with said call state control function and to communicate with said mobile station using at least one of a wireless local area network protocol, a Bluetooth™

protocol and a short range point-to-point radio protocol.

17. The system according to claim 16, the system further comprising:

a session border controller configured to communicate with said mobile station via said second base transceiver station and to transmit said at least one first media bearer over Internet Protocol towards said media gateway.

18. The system according to claim 12, wherein said first call control node and said second call control node are mobile switching center servers.

19. The system according to claim 12, wherein said radio resources comprise at least one radio channel.

20. The system according to claim 19, wherein each said at least one radio channel comprises at least one of a carrier frequency, a timeslot, a spreading code and an orthogonal frequency division multiplexing sub-carrier.

21. The system according to claim 12, wherein said mobile station comprises a session initiation protocol user agent.

22. The system according to claim 12, wherein said system comprises an IP multimedia subsystem.

23. An apparatus, comprising:

a call controller configured to

request an allocation of a first media gateway,

receive a handover request from a mobile station via a call state control function,

determine an identity of a second call control node based on cell information in said handover request,

send the handover request to said second call control node,

receive a handover number from said second call control node in response to said handover request,

route a handover session from said first call control node to said second call control node using said handover number,

receive an answer message from said second call control node,

receive a handover completion message from said call state control function, and

request a removing of at least one packet switched media bearer from said media gateway.

24. The apparatus according to claim 23, wherein said first call control node and said second call control node are mobile switching center servers.

25. The apparatus according to claim 23, wherein said at least one packet switched media bearer is transmitted over Internet Protocol between said mobile station and said first media gateway.

26. The apparatus according to claim 23, wherein radio resources for said mobile station comprise at least one radio channel.

27. The apparatus according to claim 23, wherein said mobile station comprises a session initiation protocol user agent.

28. The apparatus according to claim 23, wherein a communication system of the call control nodes comprises an IP multimedia subsystem.

29. A computer program embodied on a computer readable medium, wherein when the computer program is executed the computer program is configured to control a processor to perform:

receiving a session set-up message from a mobile station to a call state control function;

determining inter-system handover support of the mobile station in said call state control function;

providing said session set-up message to a first call control node in response to said inter-system handover support of said mobile station;

requesting an allocation of a first media gateway from said first call control node;

receiving a handover request to said first call control node from said mobile station via said call state control function;

determining in said first call control node an identity of a second call control node based on cell information in said handover request;

sending the handover request from said first call control node to said second call control node;

receiving a handover number to said first call control node from said second call control node in response to said handover request;

routing a handover session from said first call control node to said second call control node using said handover number;

receiving an answer message to said first call control node from said second call control node;

receiving a handover completion message to said first call control node from said call state control function; and

requesting a removing of at least one packet switched media bearer from said media gateway.

30. The computer program according to claim 29, wherein said computer readable medium is a removable memory card.

31. The computer program according to claim 29, wherein said computer readable medium is a magnetic or an optical disk.

32. An apparatus, comprising:

set-up receiving means for receiving a session set-up message from a mobile station to a call state control function;

determining means for determining inter-system handover support of the mobile station in said call state control function;

sending means for providing said session set-up message to a first call control node in response to said inter-system handover support of said mobile station;

allocation means for requesting an allocation of a first media gateway from said first call control node;

receiving means for receiving a handover request to said first call control node from said mobile station via said call state control function;

determining means for determining in said first call control node an identity of a second call control node based on cell information in said handover request;

handover request means for sending the handover request from said first call control node to said second call control node;

routing information receiving means for receiving a handover number to said first call control node from said second call control node in response to said handover request;

routing means for routing a handover session from said first call control node to said second call control node using said handover number;

answer means receiving an answer message to said first call control node from said second call control node;

handover completion means for receiving a handover completion message to said first call control node from said call state control function; and

removal requesting means for requesting a removing of at least one packet switched media bearer from said media gateway.