Centralized wireless LAN load balancing

• US 7,480,264 B1
• Filed: 02/10/2005
• Issued: 01/20/2009
• Est. Priority Date: 02/10/2005
• Status: Expired due to Fees

• Current Assignee: Quest Software, Inc.
• Original Assignee: SonicWALL, Inc. (SonicWall Holdings Ltd.)
• Inventors: Duo, Zhuangzhi, Chen, Zhong
• Primary Examiner(s): Orgad; Edan
• Assistant Examiner(s): Wyllie; Christopher T
• Application Number:
  US11/056,525
• Time in Patent Office: 1,440 Days
• Field of Search: 370/310.2, 370/317, 370/328, 370/332, 370/333, 370/400, 370/401, 370/468, 370/229, 370/230.1
• US Class Current: 370/310.2
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/125 by balancing the load, e.g. traffic engineering
• CPC Class Codes: H04W 24/02 Arrangements for optimising operational condition
• CPC Class Codes: H04W 28/0236 radio quality, e.g. interference, losses or delay
• CPC Class Codes: H04W 48/06 based on traffic conditions
• CPC Class Codes: H04W 48/20 Selecting an access point
• CPC Class Codes: H04W 8/04 Registration at HLR or HSS [Home Subscriber Server]
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]

Abstract

A centralized wireless LAN load balancing mechanism is described herein. In one embodiment, in response to a request for entering a wireless network from a wireless station and forwarded from multiple access points (APs) of the wireless network, a network access device coupled to the multiple APs determines a load for each of the APs. The network access device then selects one of the APs based on the determined loads of the APs and instructs the selected AP to associate with the wireless station. The network access device further instructs the remaining APs to reject the request. Other methods and apparatuses are also described.

Claims

1. A computer implemented method, comprising:

in response to a request for entering a wireless network from a wireless station and forwarded from a plurality of access points (APs), a network access device coupled to the plurality of APs determining a load for each of the APs, including calculating a weight for each AP according to a predetermined algorithm, the weight representing the load for the respective AP based on at least one of the number of wireless stations associated with the respective AP, the RSSI between the respective AP and the wireless station of the request, and the FER of the respective AP, wherein calculating a weight for each AP according to a predetermined algorithm comprises;

calculating a first variance of mean RSSI of the respective AP prior to receiving the request from the wireless station,

calculating a second variance of mean RSSI of the respective AP after receiving the request from the wireless station, wherein the weight of the respective AP is determined based on the first and second variances of mean RSSI; and

the network access device selecting one of the APs based on the determined loads of the APs to associate with the wireless station, including selecting an AP having a weight that satisfies a predetermined category to associate with the wireless station, while causing a remainder of the APs to reject the request,

wherein the load of each AP is determined based on a number of wireless stations associated with the respective AP and a received signal strength indication (RSSI) between the respective AP and the wireless station of the request, wherein the load of each AP is determined further based on a frame error rate (FER) of the respective AP.

2. The method of claim 1, wherein the network access device is a gateway device interfacing the wireless network with another network.

3. The method of claim 1, wherein the load of each AP is determined based on a number of wireless stations associated with the respective AP and a received signal strength indication (RSSI) between the respective AP and the wireless station of the request.

4. The method of claim 3, wherein the load of each AP is determined further based on a frame error rate (FER) of the respective AP.

5. The method of claim 4, further comprising:

the network access device calculating a weight for each AP according to a predetermined algorithm, the weight representing the load for the respective AP based on at least one of the number of wireless stations associated with the respective AP, the RSSI between the respective AP and the wireless station of the request, and the FER of the respective AP; and

selecting an AP having a weight that satisfies a predetermined category to associate with the wireless station.

6. The method of claim 1, wherein the weight of the respective AP is determined based on a difference between the first and second variances of mean RSSI.

7. The method of claim 1, wherein calculating a weight for each AP according to a predetermined algorithm further comprises calculating a quota mean of RSSI for each AP based on the second variance of mean RSSI of the respective AP and a maximum RSSI received by the respective AP, wherein the weight of the respective AP is determined further based on quota mean of RSSI of the respective AP.

8. The method of claim 7, wherein the weight of each AP is calculated as a product of a difference between the first and second variances of mean RSSI, the quota mean of RSSI, and the FER of the respective AP.

9. The method of claim 4, further comprising, in response to the request received from the wireless station, each AP transmitting a first message to the network access device, the first message including at least one of the number of wireless stations associated with the respective AP, the received RSSI of the wireless station requesting, and the FER of the respective AP.

10. The method of claim 9, further comprising, in response to the first message from each AP, the network access device is to calculate the load for each AP based on the received first message, to select one of the APs having the load satisfying a predetermined category, and to send a second message to the selected AP to instruct the selected AP to accept the request.

11. The method of claim 10, further comprising the network access device sending a third message to a remainder of the APs to reject the request.

12. The method of claim 9, wherein the request received from the wireless station is an IEEE 802.11 compatible probe request message, wherein the selected AP responds with an IEEE 802.11 compatible probe response message to accept the probe request, and wherein a remainder of the APs responds with an IEEE 802.11 compatible probe response message having one or more predetermined bits altered to reject the probe request.

13. The method of claim 12, wherein the IEEE 802.11 compatible probe response message having the one or more predetermined bits altered indicates that the request has been rejected by the respective AP, and wherein the IEEE 802.11 compatible probe response message having the one or more predetermined bits unaltered indicates that the request has been accepted by the respective AP.

14. The method of claim 12, wherein the remainder of the APs responds with an IEEE 802.11 compatible probe response message having a privacy bit inverted.

15. A computer-readable storage medium embedded with instructions to cause a machine to perform a method, the method comprising:

in response to a request for entering a wireless network from a wireless station and forwarded from a plurality of access points (APs), a network access device coupled to the plurality of APs determining a load for each of the APs, including calculating a weight for each AP according to a predetermined algorithm, the weight representing the load for the respective AP based on at least one of the number of wireless stations associated with the respective AP, the RSSI between the respective AP and the wireless station of the request, and the FER of the respective AP, wherein calculating a weight for each AP according to a predetermined algorithm comprises;

calculating a first variance of mean RSSI of the respective AP prior to receiving the request from the wireless station, and

calculating a second variance of mean RSSI of the respective AP after receiving the request from the wireless station, wherein the weight of the respective AP is determined based on the first and second variances of mean RSSI; and

the network access device selecting one of the APs based on the determined loads of the APs to associate with the wireless station, including selecting an AP having a weight that satisfies a predetermined category to associate with the wireless station, while causing a remainder of the APs to reject the request,

wherein the load of each AP is determined based on a number of wireless stations associated with the respective AP and a received signal strength indication (RSSI) between the respective AP and the wireless station of the request, wherein the load of each AP is determined further based on a frame error rate (FER) of the respective AP.

16. The computer-readable storage medium of claim 15, wherein the load of each AP is determined based on a number of wireless stations associated with the respective AP and a received signal strength indication (RSSI) between the respective AP and the wireless station of the request.

17. The computer-readable storage medium of claim 16, wherein the load of each AP is determined further based on a frame error rate (FER) of the respective AP.

18. A system, comprising:

a network access device; and

a plurality of access points (APs) coupled to the network access device, each of the APs being capable of wirelessly communicating with one or more wireless stations over a wireless network,

wherein in response to a request for entering the wireless network and forwarded from one or more of the APs, the network access device coupled to the plurality of APs determining a load for each of the APs, including calculating a weight for each AP according to a predetermined algorithm, the weight representing the load for the respective AP based on at least one of the number of wireless stations associated with the respective AP, the RSSI between the respective AP and the wireless station of the request, and the FER of the respective AP, wherein calculating a weight for each AP according to a predetermined algorithm comprises;

calculating a first variance of mean RSSI of the respective AP prior to receiving the request from the wireless station,

calculating a second variance of mean RSSI of the respective AP after receiving the request from the wireless station, wherein the weight of the respective AP is determined based on the first and second variances of mean RSSI; and

the network access device selecting one of the APs based on the determined loads of the APs to associate with the wireless station, including selecting an AP having a weight that satisfies a predetermined category to associate with the wireless station, whiling causing a remainder of the APs to reject the request,

wherein the load of each AP is determined based on a number of wireless stations associated with the respective AP and a received signal strength indication (RSSI) between the respective AP and the wireless station of the request, wherein the load of each AP is determined further based on a frame error rate (FER) of the respective AP.