Efficient handoffs between cellular and wireless local area networks

• US 20040008645A1
• Filed: 12/20/2002
• Published: 01/15/2004
• Est. Priority Date: 05/28/2002
• Status: Active Grant

• Current Assignee: RPX Clearinghouse LLC (RPX Corporation)
• Original Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Inventors: Janevski, Goran, Gage, Bill, Syed, Hamid
• Granted Patent: US 7,583,632 B2
• Time in Patent Office: Days
• US Class Current: 370/331
• CPC Class Codes: H04W 36/0033 with transfer of context information
• 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

Abstract

The present invention facilitates a handoff between cellular and wireless local area networks (WLANs). To facilitate a WLAN interface with the cellular network, a proxy packet control function (P-PCF) establishes a data tunnel to a packet data serving node (PDSN), as well as a WLAN association with a mobile terminal. The WLAN association is a tunnel, and is preferably implemented via an Access Router acting as a liaison between the proxy PCF and an Access Point. The Access Router and the proxy PCF establish an IP tunnel, which carries the WLAN user'"'"'s PPP traffic. Handoffs between the cellular and WLAN networks are facilitated by effecting a same-PDSN, inter-PCF handoff wherein the communication session with the mobile terminal is effectively changed from between the PDSN and the proxy PCF to between the PDSN and a PCF associated with a base station controller facilitating the cellular access, and vice versa.

Claims

1. A method for facilitating a handoff between a cellular network and wireless local area network, WLAN, the method comprising:

a) providing a communication session to a mobile terminal from a packet data serving node via a first packet control function associated with a base station controller capable of facilitating cellular access for the mobile terminal;

b) determining a need for a handoff to provide the communication session to the mobile terminal via a second packet control function capable of facilitating WLAN access for the mobile terminal;

c) terminating the communication session to the mobile terminal via the first packet control function; and

d) providing the communication session to the mobile terminal via the second packet control function such that the handoff of the communication session occurs from the cellular network to the WLAN.

2. The method of claim 1 further comprising:

a) establishing a WLAN association between an Access Router and the mobile terminal;

b) establishing a first data tunnel between the Access Router and the second packet control function; and

c) establishing a second data tunnel between the second packet control function and the packet data serving node wherein the WLAN association, first data tunnel, and second data tunnel are associated to provide the communication session via the second packet control function.

3. The method of claim 2 wherein the communication session provided via the first packet data function is facilitated by a radio channel between the mobile terminal and the base station controller associated with a third data tunnel between the first packet control function and the packet data serving node and the step of terminating the communication session further comprises removing the third data tunnel prior to establishing the second data tunnel between the second packet control function and the packet data serving node.

4. The method of claim 3 wherein packet flow for the communication session changes from between the packet data serving node and the first packet control function to between the packet data serving node and the second packet control function.

5. The method of claim 2 wherein establishing the WLAN association between the access router and the mobile terminal comprises establishing a wireless link between the mobile terminal and an access point as well as establishing a communication link between the access point and the second packet control function.

6. The method of claim 1 further comprising:

a) establishing a first radio channel between the mobile terminal and the base station controller; and

b) establishing a first data tunnel between the first packet control function and the packet data serving node wherein the first radio channel and the first data tunnel are associated to provide the communication session via the first packet control function.

7. The method of claim 1 further comprising:

a) receiving at the second packet control function a handoff signal originating from the mobile terminal to determine a need for the handoff; and

b) signaling the packet data serving node from the second packet control function to initiate the handoff by terminating the communication session to the mobile terminal via the first packet control function and providing the communication session to the mobile terminal via the second packet control function.

8. The method of claim 1 further comprising:

a) determining a need for a handoff to provide the communication session to the mobile terminal via the first packet control function;

b) terminating the communication session to the mobile terminal via the second packet control function; and

c) providing the communication session to the mobile terminal via the first packet control function such that the handoff of the communication session occurs from the WLAN to the cellular network.

9. The method of claim 1 wherein the cellular network is a cdma2000 network.

10. The method of claim 9 wherein the WLAN is an 802.11-based WLAN.

11. The method of claim 10 wherein the cellular network is a cdma2000 network.

12. The method of claim 1 wherein the communication session is at least in part facilitated using a point-to-point protocol.

13. A method for facilitating a handoff between a wireless local area network, WLAN, and a cellular network, the method comprising:

a) providing a communication session to a mobile terminal from a packet data serving node via a first packet control function capable of facilitating WLAN access for the mobile terminal;

b) determining a need for a handoff to provide the communication session to the mobile terminal via a second packet control function associated with a base station controller capable of facilitating cellular access for the mobile terminal;

c) terminating the communication session to the mobile terminal via the first packet control function; and

d) providing the communication session to the mobile terminal via the second packet control function such that the handoff of the communication session occurs from the WLAN to the cellular network.

14. The method of claim 13 further comprising:

a) establishing a first radio channel between the mobile terminal and the base station controller; and

b) establishing a first data tunnel between the first packet control function and the packet data serving node wherein the first radio channel and the first data tunnel are associated to provide the communication session via the first packet control function.

15. The method of claim 14 wherein the communication session provided via the first packet data function is facilitated by a WLAN association between an Access Router and the mobile terminal, a second data tunnel between the Access Router and the second packet control function, and a third data tunnel between the second packet control function and the packet data serving node;

and the step of terminating the communication session further comprises removing the third data tunnel prior to establishing the second data tunnel.

16. The method of claim 15 wherein packet flow for the communication session changes from between the packet data serving node and the first packet control function to between the packet data serving node and the second packet control function.

17. The method of claim 13 further comprising:

a) establishing a WLAN association between an access router and the mobile terminal;

b) establishing a first data tunnel between the Access Router and the first packet control function on behalf of the mobile terminal; and

c) establishing a second data tunnel between the first packet control function and the packet data serving node wherein the WLAN association, first data tunnel, and second data tunnel are associated to provide the communication session via the first packet control function.

18. The method of claim 17 wherein establishing the WLAN association between the access router and the mobile terminal comprises establishing a wireless link between the mobile terminal and an access point as well as establishing a communication link between the access point and the second packet control function.

19. The method of claim 13 further comprising:

a) receiving at the second packet control function an origination signal originating from the mobile terminal to determine a need for the handoff; and

signaling the packet data serving node from the second packet control function to initiate the handoff by terminating the communication session to the mobile terminal via the first packet control function and providing the communication session to the mobile terminal via the second packet control function.

20. The method of claim 13 wherein the origination signal from the mobile terminal includes information indicative of the handoff from the WLAN network to the cellular network.

21. The method of claim 13 further comprising:

a) determining a need for a handoff to provide the communication session to the mobile terminal via the first packet control function;

b) terminating the communication session to the mobile terminal via the second packet control function; and

c) providing the communication session to the mobile terminal via the first packet control function such that the handoff of the communication session occurs from the cellular network to the WLAN.

22. The method of claim 13 wherein the cellular network is a cdma2000 network.

23. The method of claim 22 wherein the WLAN is an 802.11-based WLAN.

24. The method of claim 23 wherein the cellular network is a cdma2000 network.

25. The method of claim 13 wherein the communication session is at least in part facilitated using a point-to-point protocol.

26. A method for facilitating a handoff between a cellular network and a wireless local area network, WLAN, comprising:

a) providing a communication session to a mobile terminal via a first packet control function;

b) determining a need for a handoff to provide the communication session to the mobile terminal via a second packet control function; and

c) providing the communication session to the mobile terminal via the second packet control function, the first packet control function facilitating the communication session between a packet data serving node and the mobile terminal via one of a cellular access or WLAN access and the second packet control function facilitating the communication session via an other of the cellular access or WLAN access.

27. The method of claim 26 wherein the cellular network is a cdma2000 network.

28. The method of claim 27 wherein the WLAN is an 802.11-based WLAN.

29. The method of claim 28 wherein the cellular network is a cdma2000 network.

30. The method of claim 26 wherein the communication session is at least in part facilitated using a point-to-point protocol.

31. A system for facilitating a handoff between a wireless local area network, WLAN, and a cellular network, the system comprising:

a) at least one network interface; and

b) a control system associated with the at least one interface and adapted to;

i) determine a need for a handoff to provide a communication session to a mobile terminal, which is being provided the communication session via a packet control function associated with a base station controller capable of facilitating cellular access for the mobile terminal;

ii) send a message to a packet data serving node to facilitate a handoff from the packet control function network; and

iii) establish a WLAN association with the mobile terminal and a first data tunnel with a packet data control serving node to provide the communication session between the mobile terminal and the packet data serving node.

32. The system of claim 31 wherein once the WLAN association with the mobile terminal is established, the control system is further adapted to cooperate with the packet data serving node to terminate the first data tunnel with the packet data serving node to facilitate a handoff to the packet control function.

33. The system of claim 31 wherein the control system is adapted to establish the WLAN association by establishing a communication link with an Access Router, which further establishes a wireless link with an Access Point providing a wireless link with the mobile terminal.

34. The system of claim 31 wherein the control system determines a need for the handoff upon receiving an origination signal originating from the mobile terminal.