Making roaming decisions based on association qualities between wireless devices and wireless access points

• US 7,447,176 B2
• Filed: 06/03/2003
• Issued: 11/04/2008
• Est. Priority Date: 06/03/2003
• Status: Expired due to Fees

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Abhishek, Abhishek, Ruan, Jiandong, Ayyagari, Arun
• Primary Examiner(s): Nguyen; Duc M
• Application Number:
  US10/454,247
• Publication Number:
  US 20040246922A1
• Time in Patent Office: 1,981 Days
• Field of Search: 370/331, 370/332, 370/333, 370/338, 455/41.2, 455436-440
• US Class Current: 370/331
• CPC Class Codes: H04W 48/20 Selecting an access point
• CPC Class Codes: H04W 8/02 Processing of mobility data, e.g. registration information at HLR [Home Location Register] or VLR [Visitor Location Register]; Transfer of mobility data, e.g. between HLR, VLR or external networks
• CPC Class Codes: H04W 80/00 Wireless network protocols or protocol adaptations to wireless operation
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]

Abstract

The principles of the present invention provides for making roaming decisions based on association qualities between a wireless device and one or more wireless access points. From time to time, the wireless device updates a current association quality for a current wireless access point, for example, based on relative signal strength, observed error rates, and current wireless access point workload. Similarly, the wireless device updates association qualities for any other wireless access points the wireless device can communicate with. If the current association quality falls below a quality threshold, the wireless device roams to attempt to associate with another wireless access point. The wireless device ranks compatibly configured wireless access points based at least in part on corresponding association qualities. The wireless device can attempt to associate with higher ranked wireless access points before lower ranked wireless access points.

Claims

1. At a wireless device in a wireless local area network environment that includes a plurality of wireless access points and a wireless device that is currently associated with a current wireless access point from among the plurality of wireless access points, a method for determining whether the wireless device should roam to associate with another of the wireless access points, the method comprising the following performed by the wireless device:

an act of calculating an association quality for the current wireless access point based on a plurality of parameters relevant to the quality of the current association including received signal strength measurements, error rate observations, and an access point availability parameter;

an act of determining that the association quality for the current wireless access point is insufficient, the determination indicating that the association quality is below a user-defined threshold association quality value which indicates a level of quality at which the wireless device attempts to roam to a different wireless access point;

an act of calculating an association quality for at least one of the other wireless access points of the plurality of wireless access points based on a plurality of parameters relevant to the quality of at least one of the other wireless access points including received signal strength measurements, error rate observations, and an access point availability parameter;

an act of comparing the association quality of the current wireless access point to the association quality of the at least one of the other wireless access points to determine which of the at least one other wireless access points is optimal based on a weighting of the plurality of parameters; and

an act of determining that the wireless device should attempt to associate with the determined optimal other wireless access point.

2. The method as recited in claim 1, wherein the act of calculating an association quality for the current wireless access point comprises an act of calculating an association quality based on the signal strength of the current wireless access point.

3. The method as recited in claim 1, wherein the act of calculating an association quality for the current wireless access point comprises an act of calculating an association quality based on the available resources at the current wireless access point.

4. The method as recited in claim 3, wherein an act of calculating an association quality based on the availability resources at the current wireless access point comprises an act of calculating an association quality based on radio frequency availability.

5. The method as recited in claim 3, wherein an act of calculating an association quality based on the availability resources at the current wireless access point comprises an act of calculating an association quality based on processor availability.

6. The method as recited in claim 3, wherein an act of calculating an association quality based on the availability resources at the current wireless access point comprises an act of calculating an association quality based on memory availability.

7. The method as recited in claim 3, wherein an act of calculating an association quality based on the availability resources at the current wireless access point comprises an act of calculating an association quality based on an access point availability parameter that collectively represents the availability of a plurality of different wireless access point resources.

8. The method as recited in claim 1, wherein the act of calculating an association quality for the current wireless access point comprises an act of calculating an association quality based an error rate of data packets sent from the current wireless access point.

9. The method as recited in claim 1, wherein the act of determining that the association quality for the current wireless access point is insufficient comprises an act of detecting that the association quality for the current wireless access point is below a quality threshold value.

10. The method as recited in claim 1, wherein the act of calculating an association quality for at least one of the other wireless access points of the plurality of wireless access points comprises an act of calculating an association quality for at least one of the other wireless access points based on the on the available resources at the at least one of the other wireless access points.

11. The method as recited in claim 1, wherein the act of calculating an association quality for at least one of the other wireless access points of the plurality of wireless access points comprises an act of calculating an association quality for at least one of the other wireless access points based on the on the signal strength of the at least one of the other wireless access points.

12. The method as recited in claim 1, wherein the act of comparing the association quality of the current wireless access point to the association quality of the at least one of the other wireless access points comprises an act of comparing an association quality value for the current wireless access points to an association quality value for at least one of the other wireless access points.

13. The method as recited in claim 1, wherein the act of determining that the wireless device should attempt to associate with one of the at least one of the other wireless access points comprises an act of the wireless device roaming.

14. The method as recited in claim 1, further comprising:

an act of storing the calculated association quality for the current wireless access point in a corresponding entry of an access point list.

15. The method as recited in claim 1, further comprising:

an act of storing the calculated association qualities for the at least one of the other wireless access point in corresponding entries of an access point list.

16. The method as recited in claim 1, further comprising:

an act of receiving a packet from the current wireless access point that includes an access point availability parameter.

17. The method as recited in claim 16, wherein the act of receiving a packet from the current wireless access point that includes an access point availability parameter comprises an act of receiving a packet that includes one or more access point configuration parameters.

18. At a wireless device, in a wireless local area network environment that includes a plurality of wireless access points and a wireless device that is currently associated with a current wireless access point from among the plurality of wireless access points, a method for determining whether the wireless device should roam to associate with another of the wireless access points, the method comprising the following performed by the wireless device:

an act of calculating an association quality for the current wireless access point based on a plurality of parameters relevant to the quality of the current association including received signal strength measurements, error rate observations, and an access point availability parameter;

an act of determining that the association quality for the current wireless access point is insufficient, the determination indicating that the association quality is below a user-defined threshold association quality value which indicates a level of quality at which the wireless device attempts to roam to a different wireless access point;

a step for identifying that at least one of the other wireless access points has a sufficient association quality based on a plurality of parameters relevant to the quality of at least one of the other wireless access points including received signal strength measurements, error rate observations, and an access point availability parameter;

an act of determining that the wireless device should attempt to associate with the determined optimal other wireless access points.

19. In a wireless local area network environment that includes a plurality of wireless access points and a wireless device that is associated with a current access point from among the plurality of wireless access points, a method for identifying a new access point for the wireless device to attempt to associate with when the association quality for the current access point is insufficient, the method comprising the following performed by the wireless device:

an act of creating a candidate list of one or more wireless access points from among the plurality of wireless access points, the candidate list including wireless access points that have a configuration appropriate for communicating with the wireless device;

an act of generating a ranked candidate list by assigning a corresponding rank to each wireless access point in the candidate list, the corresponding rank for each wireless access point being calculated at least in part based on an association quality between the access point and the wireless device, the association quality being based on a plurality of parameters relevant to the quality of at least one of the other wireless access points including received signal strength measurements, error rate observations, and an access point availability parameter;

an act of determining that the association quality for the current wireless access point is insufficient, the determination indicating that the association quality is below a user-defined threshold association quality value which indicates a level of quality at which the wireless device attempts to roam to a different wireless access point;

an act of selecting a ranked wireless access point from the ranked candidate list; and

an act of attempting to associate with the selected ranked wireless access point.

20. The method as recited in claim 19, wherein the act of creating a candidate list of one or more wireless access points from among the plurality of wireless access points comprises an act of identifying wireless access points that are operating in infrastructure mode.

21. The method as recited in claim 19, wherein the act of creating a candidate list of one or more wireless access points from among the plurality of wireless access points comprises an act of identifying wireless access points having a service set identifier matching a service set identifier requested by the wireless device.

22. The method as recited in claim 19, wherein the act of creating a candidate list of one or more wireless access points from among the plurality of wireless access points comprises an act of identifying wireless access points having a data rate value matching a data rate value requested by the wireless device.

23. The method as recited in claim 19, wherein the act of creating a candidate list of one or more wireless access points from among the plurality of wireless access points comprises an act of identifying wireless access points having a privacy settings matching that match privacy settings requested by the wireless device.

24. The method as recited in claim 23, wherein the act of identifying wireless access points having a privacy settings matching that match privacy settings requested by the wireless device comprise an act of identifying a wireless access point that supports Wired Equivalent Privacy encryption.

25. The method as recited in claim 19, wherein the act of creating a candidate list of one or more wireless access points from among the plurality of wireless access points comprises an act of retrieving one or more entries from an access points list.

26. The method as recited in claim 19, wherein the act of generating a ranked candidate list by assigning a corresponding rank to each wireless access point in the candidate list comprises an act of identifying wireless access points that have a corresponding association quality above a quality threshold value.

27. The method as recited in claim 19, wherein the act of generating a ranked candidate list by assigning a corresponding rank to each wireless access point in the candidate list comprises an act of randomly assigning ranks to wireless access points having a corresponding association quality above a quality threshold value.

28. The method as recited in claim 19, wherein the act of selecting a ranked wireless access point from the ranked candidate list comprises an act of selecting the highest ranked wireless access point.

29. The method as recited in claim 19, wherein the act of attempting to associate with the selected ranked wireless access point comprises an act of wirelessly communicating with the selected ranked wireless access point.

30. The method as recited in claim 19, further comprising:

an act of retrieving association qualities for wireless access points from corresponding entries in an access point list.

31. A computer-readable medium storing a computer program for use at a wireless device in a wireless local area network environment that includes a plurality of wireless access points and a wireless device that is currently associated with a current wireless access point from among the plurality of wireless access points, the computer program implementing a method for determining whether the wireless device should roam to associate with another of the wireless access points, the computer program comprising one or more computer executable instructions that, when executed by a processor, cause the wireless device to perform the following:

calculate an association quality for the current wireless access point based on a plurality of parameters relevant to the quality of the current association including received signal strength measurements, error rate observations, and an access point availability parameter;

determine that the association quality for the current wireless access point is insufficient, the determination indicating that the association quality is below a user-defined threshold association quality value which indicates a level of quality at which the wireless device attempts to roam to a different wireless access point;

calculate an association quality for at least one of the other wireless access points of the plurality of wireless access points based on a plurality of parameters relevant to the quality of at least one of the other wireless access points including received signal strength measurements, error rate observations, and an access point availability parameter;

compare the association quality of the current wireless access point to the association quality of the at least one of the other wireless access points to determine which of the at least one other wireless access points is optimal based on a weighting of the plurality of parameters; and

determine that the wireless device should attempt to associate with the determined optimal other wireless access point.

32. The computer-readable medium storing a computer program as recited in claim 31, wherein the one or more computer-readable media include system memory.

33. A computer-readable medium storing a computer program for use in a wireless local area network environment that includes a plurality of wireless access points and a wireless device that is associated with a current access point from among the plurality of wireless access points, the computer program product for implementing a method for identifying a new access point for the wireless device to attempt to associate with when the association quality for the current access point is insufficient, the computer program product comprising one or more computer-readable media having stored thereon computer executable instructions that, when executed by a processor, cause the wireless device to perform the following:

create a candidate list of one or more wireless access points from among the plurality of wireless access points, the candidate list including wireless access points that have a configuration appropriate for communicating with the wireless device;

generate a ranked candidate list by assigning a corresponding rank to each wireless access point in the candidate list, the corresponding rank for each wireless access point being calculated at least in part based on an association quality between the access point and the wireless device, the association quality being based on a plurality of parameters relevant to the quality of at least one of the other wireless access points including received signal strength measurements, error rate observations, and an access point availability parameter;

an act of determining that the association quality for the current wireless access point is insufficient, the determination indicating that the association quality is below a user-defined threshold association quality value which indicates a level of quality at which the wireless device attempts to roam to a different wireless access point;

select a ranked wireless access point from the ranked candidate list; and

attempt to associate with the selected ranked wireless access point.

34. The computer-readable medium storing a computer program as recited in claim 33, wherein the one or more computer-readable media include system memory.

35. In a wireless device, one or more computer-readable media having stored thereon a data structure for representing an entry in an access point list, the data structure comprising the following:

an access point identifier field representing an access point identifier for identifying a wireless access point that can wirelessly communicate with the wireless device;

a quality parameter field representing an association quality value that indicates the association quality between the wireless device and the wireless access point identified in the access point identifier field, the association quality being based on a plurality of parameters relevant to the quality of the current association including received signal strength measurements, error rate observations, and an access point availability parameter, the quality parameter field indicating that the association quality is below a user-defined threshold association quality value which indicates a level of quality at which the wireless device attempts to roam to a different wireless access point; and

an AP configuration parameters field representing one or more configuration values that indicate the configuration of the wireless access point identified in the access point identifier field.