Distributed seamless roaming in wireless networks

• US 9,730,117 B2
• Filed: 01/04/2016
• Issued: 08/08/2017
• Est. Priority Date: 10/19/2012
• Status: Active Grant

• Current Assignee: Ubiquiti Inc.
• Original Assignee: Ubiquiti Networks, Inc. (Ubiquiti Inc.)
• Inventors: Dayanandan, Sriram, Pera, Robert J., Luoh, Keh-Ming, Yang, Bo-chieh, Lee, Yuan-Hsiang
• Primary Examiner(s): Pezzlo, John
• Application Number:
  US14/987,688
• Publication Number:
  US 20160119827A1
• Time in Patent Office: 582 Days
• Field of Search: 370462, 370252, 370329
• CPC Class Codes: H04L 5/0055 Physical resource allocation for ACK/NACK for physical mapping arrangements in ARQ protocols H04L1/1861
• CPC Class Codes: H04W 36/0044 of quality context information
• CPC Class Codes: H04W 36/0094 Definition of hand-off measurement parameters
• CPC Class Codes: H04W 36/18 for allowing seamless reselection, e.g. soft reselection
• CPC Class Codes: H04W 36/30 by measured or perceived connection quality data
• CPC Class Codes: H04W 4/06 Selective distribution of broadcast services, e.g. multimedia broadcast multicast service [MBMS]; Services to user groups; One-way selective calling services
• CPC Class Codes: H04W 48/16 Discovering, processing access restriction or access information
• CPC Class Codes: H04W 72/542 using measured or perceived quality
• 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 84/12 WLAN [Wireless Local Area Networks]
• CPC Class Codes: H04W 84/18 Self-organising networks, e.g. ad-hoc networks or sensor networks
• CPC Class Codes: H04W 88/08 Access point devices

Abstract

One embodiment of the present invention provides a system for configuring an access point in a wireless network. During operation, the access point discovers one or more existing access points associated with the wireless network. The access point then obtains a set of configuration information from one existing access point, and synchronizes a local timestamp counter to a selected existing access point, thereby allowing the access point to be configured without using a centralized management station.

Claims

1. A method for conducting a maintenance procedure at an access point without disrupting access to a wireless network, comprising:

responsive to a local access point of the wireless network detecting a maintenance condition for performing a maintenance procedure, handing over one or more user stations associated with the local access point to other access points of the wireless network;

performing the maintenance procedure;

responsive to the local access point completing the maintenance procedure, obtaining a set of configuration information from an existing access point that belongs to the wireless network; and

in response to determining that the local access point has the best signal strength of a user station, allowing the user station to be associated with the local access point.

2. The method of claim 1, wherein performing the maintenance procedure involves conducting a spectrum scan to select a best available frequency.

3. The method of claim 1, wherein performing the maintenance procedure involves upgrading a firmware of the local access point.

4. The method of claim 1, further comprising:

multicasting a station query message to the other access points, wherein the station query message includes at least a media access control (MAC) address for the user station; and

receiving signal strength values for the user station from the other access points.

5. The method of claim 1, wherein allowing the user station to be associated with the local access point involves:

comparing the local access point'"'"'s signal strength value for the user station to signal strength values for the user station from the other access points; and

determining that the local access point'"'"'s signal strength value is the highest signal strength for the user station.

6. The method of claim 1, wherein handing over a user station to a remote access point involves:

flushing out any remaining packets for the user station in a local buffer; and

responsive to determining that the local buffer does not include a packet for the user station, removing the user station from an associated station list for the local access point.

7. The method of claim 1, wherein handing over a user station to a remote access point involves:

sending a handover request message to the remote access point; and

in response to receiving a switch request message from the remote access point, sending to the remote access point a switch response message that includes at least an association identifier for the user station.

8. The method of claim 7, wherein the switch response message also includes one or more of:

one or more 802.11 association information elements;

station information; and

802.11 block-ACK and aggregation states for one or more traffic identifiers (TIDs).

9. A wireless access point, comprising a processor and a memory coupled to the processor and storing instructions which when executed by the processor cause the processor to perform a method for conducting a maintenance procedure at the wireless access point without disrupting access to a wireless network, the method comprising:

responsive to the local wireless access point detecting a maintenance condition for performing a maintenance procedure, handing over one or more user stations associated with the local access point to other access points of the wireless network;

performing the maintenance procedure;

responsive to the local wireless access point completing the maintenance procedure, obtaining a set of configuration information from an existing access point that belongs to the wireless network; and

in response to determining that the local wireless access point has the best signal strength of a user station, allowing the user station to be associated with the local wireless access point.

10. The wireless access point of claim 9, wherein performing the maintenance procedure involves conducting a spectrum scan to select a best available frequency.

11. The wireless access point of claim 9, wherein performing the maintenance procedure involves upgrading a firmware of the local wireless access point.

12. The wireless access point of claim 9, further comprising:

multicasting a station query message to the other access points, wherein the station query message includes at least a media access control (MAC) address for the user station; and

receiving signal strength values for the user station from the other access points.

13. The wireless access point of claim 9, wherein allowing the user station to be associated with the local wireless access point involves:

comparing the local wireless access point'"'"'s signal strength value for the user station to signal strength values for the user station from the other access points; and

determining that the local wireless access point'"'"'s signal strength value is the highest signal strength for the user station.

14. The wireless access point of claim 9, wherein handing over a user station to a remote access point involves:

flushing out any remaining packets for the user station in a local buffer; and

responsive to determining that the local buffer does not include a packet for the user station, removing the user station from an associated station list for the local wireless access point.

15. The wireless access point of claim 9, wherein handing over a user station to a remote access point involves:

sending a handover request message to the remote access point; and

in response to receiving a switch request message from the remote access point, sending to the remote access point a switch response message that includes at least an association identifier for the user station.

16. The wireless access point of claim 15, wherein the switch response message also includes one or more of:

one or more 802.11 association information elements;

station information; and

802.11 block-ACK and aggregation states for one or more traffic identifiers (TIDs).

17. A method for conducting a maintenance procedure at an access point without disrupting access to a wireless network, comprising:

responsive to a local access point of the wireless network detecting a maintenance condition for performing a spectrum scan, handing over one or more user stations associated with the local access point to other access points of the wireless network;

performing the spectrum scan to select a best available frequency for the local access point;

responsive to the local access point completing the spectrum scan, obtaining configuration information from an existing access point that belongs to the wireless network; and

in response to determining that the local access point has the best signal strength of a user station, allowing the user station to be associated with the local access point.

18. A wireless access point, comprising a processor and a memory coupled to the processor and storing instructions which when executed by the processor cause the processor to perform a method for conducting a maintenance procedure at the wireless access point without disrupting access to a wireless network, the method comprising:

responsive to the local wireless access point detecting a maintenance condition for performing a firmware upgrade procedure, handing over one or more user stations associated with the local access point to other access points of the wireless network;

performing the firmware upgrade procedure to upgrade a firmware of the local wireless access point;

responsive to the local wireless access point completing the firmware upgrade procedure, obtaining a set of configuration information from an existing access point that belongs to the wireless network; and

in response to determining that the local wireless access point has the best signal strength of a user station, allowing the user station to be associated with the local wireless access point.