Method and apparatus for handing off a mobile terminal between a mobile network and a wireless lan

• US 20050021586A1
• Filed: 12/10/2002
• Published: 01/27/2005
• Est. Priority Date: 12/19/2001
• Status: Active Grant

• Current Assignee: Thomson Licensing SA (Vantiva SA)
• Original Assignee: Thomson Licensing SA (Vantiva SA)
• Inventors: Richardson, John, Bichot, Guillaume
• Granted Patent: US 7,693,522 B2
• Time in Patent Office: Days
• US Class Current: 709/200
• CPC Class Codes: H04W 36/1446 wherein at least one of the networks is unlicensed
• CPC Class Codes: H04W 48/18 Selecting a network or a communication service
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]
• CPC Class Codes: H04W 88/06 adapted for operation in multiple networks or having at least two operational modes, e.g. multi-mode terminals

Abstract

A method for performing a handover of a mobile terminal between a 3G cell and a WLAN cell when the mobile terminal moves within a 3G cell into the coverage area of the WLAN cell. The present invention proposes that the handover be performed when there are no active calls. If there are ongoing calls, method proposes to wait until the calls are terminated before the handover is performed. After the ongoing calls are terminated, the handover is performed by disassociating from the radio access network of the 3G cell and associating with the access point of the WLAN, using the relatively straightforward disassociation and association procedures. The handover method according to the present invention obviates the need for complex and expensive protocols to ensure a seamless and error free handover of calls when moving from the coverage of the 3G cell to the coverage of the WLAN cell. This method can be used with either the loose coupling arrangement or the tight coupling arrangement.

Claims

1. A method for controlling a mobile terminal, comprising the steps of:

establishing an association with a first access network to connect to a core network;

determining when the mobile terminal is entering a coverage area of a second access network, which is overlaid within the first access network;

determining whether the mobile terminal has an active call session via the first access network when the mobile terminal enters the second access network, and if so, maintaining the association with the first access network when the mobile terminal enters the coverage area of the second access network until the active call session is terminated, and upon termination of the call session, disassociating from the first access network and establishing an association with the second access network to connect to the core network.

2. The method according to claim 1, wherein

the first access network is a 3G cell, and the second access network is a wireless LAN cell.

3. The method according to claim 2, wherein

the 3G cell and the wireless LAN are coupled to the network in a loose coupling arrangement.

4. The method according to claim 3, further comprising the step of

determining whether there is an ongoing mobility management procedure in progress when the mobile terminal enters the wireless LAN cell, and if so, maintaining the association with the first access network when the mobile terminal enters the coverage area of the second access network until the mobility management procedure is terminated.

5. The method according to claim 3, further comprising the step of

determining whether there is an ongoing radio resource control procedure in progress when the mobile terminal enters the wireless LAN cell, and if so, maintaining the association with the first access network when the mobile terminal enters the coverage area of the second access network until the radio resource control procedure is terminated.

6. The method according to claim 3, wherein

the step of disassociating from the first access network and associating with the second access network comprises receiving an RNC ID that corresponds to an access point in the wireless LAN cell.

7. The method according to claim 3, wherein

the termination of the call session is determined in response to the presence of radio and transport bearers.

8. The method according to claim 3, wherein

the association with the wireless LAN is established following the PDP context deactivation procedure between the mobile terminal and the first access network.

9. The method according to claim 3, wherein

the association with the wireless LAN is established following deactivation of circuit switch connections.

10. The method according to claim 3, wherein

the association with the wireless LAN is established following deactivation of packet switch connections.

11. The method according to claim 2, wherein

the 3G cell and the wireless LAN are coupled to the network in a tight coupling arrangement.

12. The method according to claim 11, further comprising the step of

determining whether there is an ongoing mobility management procedure in progress when the mobile terminal enters the wireless LAN cell, and if so, maintaining the association with the first access network when the mobile terminal enters the coverage area of the second access network until the mobility management procedure is terminated.

13. The method according to claim 11, further comprising the step of

determining whether there is an ongoing radio resource control procedure in progress when the mobile terminal enters the wireless LAN cell, and if so, maintaining the association with the first access network when the mobile terminal enters the coverage area of the second access network until the radio resource control procedure is terminated.

14. The method according to claim 11, wherein

the step of disassociating from the first access network and associating with the second access network comprises receiving an RNC ID that corresponds to an access point in the wireless LAN cell.

15. The method according to claim 11, wherein

the termination of the call session is determined in response to the presence of radio and transport bearers.

16. The method according to claim 11, wherein

the association with the wireless LAN is established following the PDP context deactivation procedure between the mobile terminal and the first access network.

17. The method according to claim 11, wherein

the association with the wireless LAN is established following deactivation of circuit switch connections.

18. The method according to claim 11, wherein

the association with the wireless LAN is established following deactivation of packet switch connections.