Methods and apparatus for reducing roaming latency in a mobile node

• US 20050148328A1
• Filed: 12/30/2003
• Published: 07/07/2005
• Est. Priority Date: 12/30/2003
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Leung, Patrick Pak-Chiu, Pathan, Arnavkumar M.
• Granted Patent: US 8,064,903 B2
• Time in Patent Office: Days
• US Class Current: 455/432.100
• CPC Class Codes: H04W 36/324 by mobility data, e.g. speed data
• CPC Class Codes: H04W 64/006 with additional information processing, e.g. for direction or speed determination

Abstract

Methods and apparatus for triggering roaming in a mobile network device are disclosed. A speed of the network device is detected. One or more maximum/minimum trigger values corresponding to one or more trigger events are ascertained at the speed of the network device. One or more trigger counters associated with the one or more trigger events are maintained. Roaming of the network device is triggered when one of the trigger counters associated with one of the trigger events is equal to or exceeds (or is less than or equal to) one of the trigger values corresponding to the trigger event at the speed of the network device.

Claims

1. A method of triggering roaming in a network device, comprising:

detecting a speed of the network device;

ascertaining one or more trigger values corresponding to one or more trigger events at the speed of the network device;

maintaining one or more trigger counters associated with the one or more trigger events; and

triggering roaming when one of the trigger counters associated with one of the trigger events is equal to or exceeds one of the trigger values corresponding to the one of the trigger events at the speed of the network device.

2. The method as recited in claim 1, wherein the network device is a Mobile Node implemented in a 802.11 environment.

3. The method as recited in claim 1, wherein the network device is a Mobile Node supporting Mobile IP.

4. The method as recited in claim 1, wherein roaming is triggered when the network device has reached or is nearing a perimeter of a coverage area of an Access Point to which the network device has associated or a Foreign Agent via which the network device has registered with its Home Agent

5. The method as recited in claim 1, wherein roaming is triggered when the network device is no longer within a coverage area of an Access Point to which the network device has associated or a Foreign Agent via which the network device has registered with its Home Agent.

6. The method as recited in claim 1, wherein ascertaining comprises:

obtaining the one or more trigger values from a profile, wherein the profile includes a set of one or more trigger values at a plurality of speeds.

7. The method as recited in claim 1, wherein the rate at which the network device roams increases as the speed of the network device increases.

8. The method as recited in claim 6, wherein the trigger values decrease as the speed of the network device increases.

9. The method as recited in claim 1, wherein the trigger events include at least one of maximum data retry count is exceeded, maximum number of beacons missed is exceeded, data rate shift, and signal strength

10. The method as recited in claim 9, wherein the trigger values include at least one of maximum data retry count, maximum number of beacons missed, maximum data rate shift, and minimum signal strength.

11. The method as recited in claim 10, wherein roaming is triggered when one of the trigger counters associated with the maximum data retry count is exceeded trigger event is equal to or exceeds the maximum data retry count trigger value.

12. The method as recited in claim 10, wherein roaming is triggered when one of the trigger counters associated with the maximum number of beacons missed is exceeded trigger event is equal to or exceeds the maximum number of beacons missed trigger value.

13. The method as recited in claim 10, wherein roaming is triggered when one of the trigger counters associated with the data rate shift trigger event is equal to or exceeds the maximum data rate shift trigger value.

14. The method as recited in claim 10, wherein roaming is triggered when one of the trigger counters associated with the signal strength trigger event is less than the minimum signal strength trigger value.

15. The method as recited in claim 1, wherein detecting a speed of the network device is performed using a GPS.

16. The method as recited in claim 1, wherein the network device is a Mobile Node, the method further comprising:

registering with a Home Agent via a new Foreign Agent using a new Access Point when roaming is triggered, wherein the Mobile Node is within a coverage area of the new Foreign Agent and the new Access Point.

17. The method as recited in claim 16, further comprising:

de-registering with the Home Agent via a new Foreign Agent using a new Access Point, wherein the Mobile Node is no longer within a coverage area of the previous Foreign Agent.

18. The method as recited in claim 1, wherein the network device is a Mobile Node, and wherein when roaming is triggered, the Mobile Node is no longer within a coverage area of a Foreign Agent via which the mobile node has registered with its Home Agent.

19. The method as recited in claim 1, wherein when roaming is triggered, the network device is no longer within a coverage area of an Access Point servicing the network device.

28. The method as recited in claim 1, wherein the network device is a Mobile Node, the method further comprising:

registering with a Home Agent via a Foreign Agent when roaming is triggered, wherein the Mobile Node is within a coverage area of the Foreign Agent.

29. The method as recited in claim 28, further comprising:

de-registering with the Home Agent via a new Foreign Agent, wherein the Mobile Node is no longer within a coverage area of the previous Foreign Agent.

30. The method as recited in claim 1, wherein the network device is a Mobile Node, and wherein when roaming is triggered, the Mobile Node is no longer within a coverage area of a Foreign Agent via which the mobile node has registered with its Home Agent.

20. A method of triggering roaming in a network device, comprising:

detecting a speed of the network device;

ascertaining one or more trigger values corresponding to one or more trigger events at the speed of the network device;

maintaining one or more trigger counters associated with the one or more trigger events; and

triggering roaming when one of the trigger counters associated with one of the trigger events is less than or equal to one of the trigger values corresponding to the one of the trigger events at the speed of the network device.

21. A method of triggering roaming in a network device, comprising:

detecting a speed of the network device;

modifying one or more trigger values corresponding to one or more trigger events such that the one or more trigger values correspond to the speed of the network device;

maintaining one or more trigger counters associated with the one or more trigger events; and

triggering roaming when one of the trigger counters associated with one of the trigger events is equal to or exceeds one of the trigger values corresponding to the one of the trigger events at the speed of the network device.

22. The method as recited in claim 21, wherein modifying one or more trigger values comprises:

multiplying the one or more trigger values by one or more multiplying factors, wherein each of the multiplying factors corresponds to the speed of the network device.

23. The method as recited in claim 22, wherein each of the multiplying factors decreases the one or more trigger values when the speed of the network device increases.

24. The method as recited in claim 22, wherein each of the multiplying factors increases the one or more trigger values when the speed of the network device decreases.

25. The method as recited in claim 22, further comprising:

ascertaining the multiplying factors corresponding to the speed of the network device.

26. The method as recited in claim 22, wherein multiplying comprises:

multiplying the one or more trigger values by a single multiplying factor.

27. The method as recited in claim 22, wherein multiplying comprises:

multiplying each of the trigger values by a different multiplying factor, wherein the multiplying factor corresponds to the trigger event.

31. A method of triggering roaming in a network device, comprising:

detecting a speed of the network device;

modifying one or more trigger values corresponding to one or more trigger events such that the one or more trigger values correspond to the speed of the network device;

maintaining one or more trigger counters associated with the one or more trigger events; and

triggering roaming when one of the trigger counters associated with one of the trigger events is less than or equal to one of the trigger values corresponding to the one of the trigger events at the speed of the network device.

32. A computer-readable medium storing thereon computer-readable instructions for triggering roaming in a network device, comprising:

instructions for detecting a speed of the network device;

instructions for ascertaining one or more trigger values corresponding to one or more trigger events at the speed of the network device;

instructions for maintaining one or more trigger counters associated with the one or more trigger events; and

instructions for triggering roaming when one of the trigger counters associated with one of the trigger events is equal to or exceeds one of the trigger values corresponding to the one of the trigger events at the speed of the network device.

33. An apparatus for triggering roaming in a network device, comprising:

means for detecting a speed of the network device;

means for ascertaining one or more trigger values corresponding to one or more trigger events at the speed of the network device;

means for maintaining one or more trigger counters associated with the one or more trigger events; and

means for triggering roaming when one of the trigger counters associated with one of the trigger events is equal to or exceeds one of the trigger values corresponding to the one of the trigger events at the speed of the network device.

34. An apparatus for triggering roaming in a network device, comprising:

a processor; and

a memory, at least one of the processor and the memory adapted for;

detecting a speed of the network device;

ascertaining one or more trigger values corresponding to one or more trigger events at the speed of the network device;

maintaining one or more trigger counters associated with the one or more trigger events; and

triggering roaming when one of the trigger counters associated with one of the trigger events is equal to or exceeds one of the trigger values corresponding to the one of the trigger events at the speed of the network device.