ENHANCED CROSS-NETWORK HANDOFF FOR MOBILE IP SERVICE MOBILITY

• US 20080159232A1
• Filed: 12/29/2006
• Published: 07/03/2008
• Est. Priority Date: 12/29/2006
• Status: Active Grant

• Current Assignee: United States Cellular Corporation (Telephone & Data Systems, Inc.)
• Original Assignee: United States Cellular Corporation (Telephone & Data Systems, Inc.)
• Inventors: Saxena, Narothum, Irizarry, Michael, Thalanany, Sebastian
• Granted Patent: US 8,145,210 B2
• Time in Patent Office: Days
• US Class Current: 370/332
• CPC Class Codes: H04W 36/0016 Hand-off preparation specially adapted for end-to-end data sessions
• CPC Class Codes: H04W 36/0019 adapted for mobile IP [MIP]
• CPC Class Codes: H04W 36/144 over a different radio air interface technology
• CPC Class Codes: H04W 48/18 Selecting a network or a communication service
• CPC Class Codes: H04W 80/04 Network layer protocols, e.g. mobile IP [Internet Protocol]

Abstract

A system and method are described whereby an enhanced handoff scheme provides for monitoring of mobile device conditions and network conditions associated with a current access network attachment, as well as with a plurality of access networks on a preferred access network list, to proactively initiate a handoff operation, thereby preserving the QoS constraints necessary for seamless delivery of IP multimedia services. In an embodiment, each of the plurality of access networks is connected to an IMS core network, whereby a policy function receives quality of service constraints associated with the launched application from the mobile device and orders a list of preferred access networks accordingly. Preferably, the policy function selects an appropriate access gateway associated with a target access network based at least in part on the mobile device conditions reported by the mobile device and the access network conditions monitored by the policy function.

Claims

1. A method for maintaining an IP network session according to quality of service constraints for an application running on a user device, the method comprising:

receiving a list of preferred access networks for the user device, the list comprising a plurality of access networks authorized for the user device;

receiving the quality of service constraints from the user device;

establishing the IP network session via a first access network based on the quality of service constraints, wherein the first access network is one of the plurality of networks;

monitoring user device and access network conditions for the first access network and at least some of the plurality of networks on the list of preferred access networks to determine whether the first access network is able to maintain the IP network session in accordance with the quality of service constraints for the application; and

if the first access network is not able to maintain the IP network session in accordance with the quality of service constraints, transferring the IP network session to a second access network selected based on at least one of the user device conditions and the access network conditions.

2. The method of claim 1 further comprising ordering the list of preferred access networks based on the quality of service constraints.

3. The method of claim 1 wherein the access network conditions comprise one or more network condition triggers for each of the plurality of access networks, the network condition triggers associated with the quality of service constraints for the application.

4. The method of claim 3 wherein the network condition triggers include a plurality of thresholds comprising a bandwidth threshold, a latency threshold, a packet loss threshold, and a capacity threshold.

5. The method of claim 1 wherein the user device conditions include at least one of a received signal quality indicator, a battery life indicator, and a mobility direction indicator.

6. The method of claim 5 further comprising ordering the at least some of the plurality of networks from the list of preferred access networks according to the received signal quality indicator.

7. The method of claim 5 wherein the received signal quality indicator comprises at least one of a received signal strength indicator, a bit error rate indicator, and a signal-to-noise ratio indicator.

8. The method of claim 1 wherein the user device is capable of accessing a cellular network and a Wi-Fi network.

9. The method of claim 1 further comprising controlling the IP network session via an IP Multimedia Subsystem (IMS) core network, wherein each of the plurality of access networks is connected to the IMS core network.

10. A system for maintaining an IP network session according to quality of service constraints for an application running on a user device, the system comprising:

a policy function server having a list of preferred access networks for the user device, the list comprising a plurality of access networks authorized for the user device;

the user device capable of initiating the IP network session for the application on a first access network according to the quality of service constraints, wherein the policy function server and the user device respectively monitor access network conditions and user device conditions associated with the first access network and at least some of the plurality of networks on the list of preferred access networks; and

when the first access network is not able to maintain the IP network session in accordance with the quality of service constraints, the policy function server transferring the IP network session to a second access network selected based on at least one of the user device conditions and the access network conditions.

11. The system of claim 10 wherein the policy function server orders the list of preferred access networks based on the quality of service constraints.

12. The system of claim 10 wherein the access network conditions comprise one or more network condition triggers for each of the plurality of access networks, the network condition triggers associated with the quality of service constraints for the application.

13. The system of claim 12 wherein the network condition triggers include a plurality of thresholds comprising a bandwidth threshold, a latency threshold, a packet loss threshold, and a capacity threshold.

14. The system of claim 10 wherein the user device conditions include at least one of a received signal quality indicator, a battery life indicator, and a mobility direction indicator.

15. The system of claim 14 wherein the user device orders the at least some of the plurality of networks on the list of preferred access networks according to the received signal quality indicator.

16. The system of claim 14 wherein the received signal quality indicator comprises at least one of a received signal strength indicator, a bit error rate indicator, and a signal-to-noise ratio indicator.

17. The system of claim 10 wherein the user device is capable of accessing a cellular network and a Wi-Fi network.

18. The system of claim 10 further comprising an IP Multimedia Subsystem (IMS) core network for controlling the IP network session, wherein each of the plurality of access networks is connected to the IMS core network.

19. A user device for running an application by initiating an IP network session on a first access network according to quality of service constraints for the application, wherein the user device monitors received signal quality associated with one or more access networks and sends at least one handoff parameter to a policy function server when the received signal quality associated with the first access network indicates that the first access network is not able to maintain the IP network session in accordance with the quality of service constraints;

and

wherein, in response to receiving the at least one handoff parameter, the policy function server transfers the IP network session to a second access network selected based at least in part on the at least one handoff parameter.

20. The user device of claim 19 wherein the policy function server includes a list of preferred access networks for the user device, the list ordered based on the quality of service constraints.

21. The user device of claim 20 wherein the policy function selects the second access network based on the at least one handoff parameter and the list of preferred access networks ordered based on the quality of service constraints.

22. The user device of claim 19 wherein the at least one handoff parameter comprises an ordered list of the one or more access networks based on the received signal quality monitored by the user device.

23. The user device of claim 19 wherein the received signal quality comprises at least one of a received signal strength indicator, a bit error rate indicator, and a signal-to-noise ratio indicator.

24. The user device of claim 19 wherein the user device is capable of accessing a cellular network and a Wi-Fi network.