Seamless roaming in wireless networks

• US 9,185,618 B1
• Filed: 08/28/2009
• Issued: 11/10/2015
• Est. Priority Date: 12/05/2005
• Status: Active Grant

• Current Assignee: Fortinet Inc.
• Original Assignee: Meru Networks, Inc. (Fortinet Inc.)
• Inventors: Bharghavan, Vaduvur, Dunsbergen, Berend
• Primary Examiner(s): Eng, George
• Assistant Examiner(s): Hammonds, Marcus
• Application Number:
  US12/550,061
• Time in Patent Office: 2,265 Days
• Field of Search: 370/328, 370/331, 370/338
• US Class Current: 1/1
• CPC Class Codes: H04W 24/02 Arrangements for optimising operational condition
• CPC Class Codes: H04W 36/0016 Hand-off preparation specially adapted for end-to-end data sessions
• CPC Class Codes: H04W 36/18 for allowing seamless reselection, e.g. soft reselection
• CPC Class Codes: H04W 36/38 by fixed network equipment
• CPC Class Codes: H04W 76/11 Allocation or use of connection identifiers
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]

Abstract

A system and method for providing a seamless transition between access points for mobile devices. The method comprises associating a unique identifier for a plurality of mobile stations with a unique identifier for a first network in an acknowledgment table, then, upon receiving a frame from a mobile station, acknowledging the reception of the frame if the frame includes the unique identifier for the mobile station and the unique identifier for the network. The transfer of operation between access points is effectuated through the use of control circuitry which transfers portions of the contents of the acknowledgement table between various access points. This has the effect that the mobile stations does not sense a change in access points and thus the roaming from a first access point to a second access point is seamless.

Claims

1. A computer-implemented method performed by an access point of a plurality of access points managed by a controller of a wireless communication network the method comprising the steps of:

associating a mobile station of a plurality of mobile stations with the access point by storing, at both the mobile station and the access point, a persistent, uniquely assigned BSSID (Basic Service Set Identifier) that is uniquely assigned to the mobile station among a plurality of persistent uniquely-assigned BSSIDs stored at the access point that are assigned to the plurality of mobile stations, wherein each of the plurality of access points independently using layer 2 communications and the persistent, uniquely-assigned BSSID is configured in the mobile station by the access point with a beacon frame or a probe response frame sent from the mobile station to the access point;

receiving a frame from the mobile station, the frame comprising a sender address defined by a MAC address unique to the mobile station and a receiver address defined by the persistent, uniquely-assigned BSSID;

responsive to matching the receiver address of the received frame to one of the stored plurality of persistent, uniquely-assigned BSSIDs, generating an ACK frame to send to the mobile station; and

responsive to a handoff of the mobile station from the access point to another access point of the plurality of access points, disassociating the mobile station from the access point by deleting the persistent, uniquely-assigned BSSID, wherein the another access point associates with the mobile station by storing the persistent, uniquely-assigned BSSID allowing the mobile station to seamlessly continue to store and use the same persistent, uniquely-assigned BSSID for communication with the wireless communication network.

2. The method of claim 1, further comprising:

receiving the persistent, uniquely-assigned BSSID from the controller assigning the mobile station to the access point.

3. The method of claim 1, further comprising:

receiving a message from the controller disassociating the mobile station from the access point.

4. The method of claim 1, further comprising:

responsive to not matching the receiver address of the received frame to one of the stored BSSIDs, ignoring the received frame.

5. A non-transitory computer readable medium storing a computer program product that, when executed by a processor performs a method in an access point of a plurality of access points managed by a controller of a wireless communication network the method comprising the steps of:

associating a mobile station of a plurality of mobile stations with the access point by storing, at both the mobile station and the access point, a persistent, uniquely assigned BSSID (Basic Service Set Identifier) that is uniquely assigned to the mobile station among a plurality of persistent uniquely-assigned BSSIDs stored at the access point that are assigned to the plurality of mobile stations, wherein each of the plurality of access points independently using layer 2 communications and the persistent, uniquely-assigned BSSID is configured in the mobile station by the access point with a beacon frame or a probe response frame sent from the mobile station to the access point;

receiving a frame from the mobile station, the frame comprising a sender address defined by a MAC address unique to the mobile station and a receiver address defined by the persistent, uniquely-assigned BSSID;

responsive to matching the receiver address of the received frame to one of the stored plurality of persistent, uniquely-assigned BSSIDs, generating an ACK frame to send to the mobile station; and

responsive to a handoff of the mobile station from the access point to another access point of the plurality of access points, disassociating the mobile station from the access point by deleting the persistent, uniquely-assigned BSSID, wherein the another access point associates with the mobile station by storing the persistent, uniquely-assigned BSSID allowing the mobile station to seamlessly continue to store and use the same persistent, uniquely-assigned BSSID for communication with the wireless communication network.

6. The at least one computer readable product of claim 5, further comprising:

receiving the persistent, uniquely assigned BSSID from the controller assigning the mobile station to the access point.

7. The at least one computer readable product of claim 5, further comprising:

receiving a message from the controller disassociating the mobile station from the access point.

8. The at least one computer readable product of claim 5, further comprising:

responsive to not matching the receiver address of the received frame to one of the stored persistent, uniquely-assigned BSSIDs, ignoring the received frame.

9. The at least one computer readable product of claim 5, further comprising:

receiving the persistent, uniquely assigned BSSID from the controller assigning the mobile station to the access point.

10. An access point of a plurality of access points managed by a controller of a wireless communication network, comprising:

a processor; and

a memory coupled to the processor and containing program code, which when executed cause the processor to;

associate a mobile station of a plurality of mobile stations with the access point by storing, at both the mobile station and the access point, a persistent, uniquely assigned BSSID (Basic Service Set Identifier) that is uniquely assigned to the mobile station among a plurality of persistent uniquely-assigned BSSIDs stored at the access point that are assigned to the plurality of mobile stations, wherein each of the plurality of access points independently using layer 2 communications and the persistent, uniquely-assigned BSSID is configured in the mobile station by the access point with a beacon frame or a probe response frame sent from the mobile station to the access point;

receive a frame from the mobile station, the frame comprising a sender address defined by a MAC address unique to the mobile station and a receiver address defined by the persistent, uniquely-assigned BSSID;

responsive to matching the receiver address of the received frame to one of the stored plurality of persistent, uniquely-assigned BSSIDs, generate an ACK frame to send to the mobile station; and

responsive to a handoff of the mobile station from the access point to another access point of the plurality of access points, disassociate the mobile station from the access point by deleting the persistent, uniquely-assigned BSSID, wherein the another access point associates with the mobile station by storing the persistent, uniquely-assigned BSSID allowing the mobile station to seamlessly continue to store and use the same persistent, uniquely-assigned BSSID for communication with the wireless communication network.