Wireless LAN with dynamic channel selection

• US 20020181417A1
• Filed: 04/16/2002
• Published: 12/05/2002
• Est. Priority Date: 05/08/2001
• Status: Active Grant

• Current Assignee: Alcatel-Lucent USA, Inc. (Nokia Corporation)
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Malhotra, Richa, Busch, Patrick
• Granted Patent: US 7,110,374 B2
• Time in Patent Office: Days
• US Class Current: 370/329
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 72/02 Selection of wireless resources by user or terminal
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]
• CPC Class Codes: H04W 88/08 Access point devices

Abstract

The present invention describes an algorithm for the assignment of channels used by access points (APs) in wireless LANs in a dynamic way in order to achieve the best performance. The assignment of channels is based on a procedure in which an AP is passively listening on the other channels during idle time. The AP is calculating the optimal channel with the least interference and sharing. If the AP experiences too much disturbance, it will decide to switch to the calculated optimal channel.

Claims

1. An access point for a wireless communication network, comprising a processor and memory storing data and instructions, arranged to dynamically select an optimum channel by carrying out the following steps:

(a) selecting a channel from a plurality of possible channels;

(b) collecting data as to at least level of Medium Activity on said channel during a predetermined scanning time;

(c) storing a channel interference parameter indicative of a time period in said scanning time that said level of Medium Activity exceeded a first threshold value;

(d) repeating steps (b) and (c) for all other channels of said plurality of channels;

(e) selecting said optimum channel in accordance with a predetermined rule taking said channel interference parameter into account.

2. Access point according to claim 1, wherein the following steps are carried out:

additionally storing, in step (c), a channel sharing parameter indicative of a time period in said scanning time that said level of Medium Activity exceeded a second threshold;

in step (e), selecting said optimum channel in accordance with said predetermined rule taking said channel interference parameter and said channel sharing parameter into account.

3. Access point according to claim 1, wherein said channel interference parameter, at system startup, is defined as CI(j)=T_interference(j)/T_scan(j) with T_scan(j) being said scanning time on said channel (j) and T_interference(j) being a time period in said scanning time that said level of activity exceeded said first threshold.

4. Access point according to claim 2, wherein said channel sharing parameter, at system startup, is defined as CS(j)=T_sharing(j)/T_scan(j) with T_scan(j) being said scanning time on said channel (j) and T_sharing(j) being a time period in said scanning time that said level of Medium Activity exceeded said second threshold.

5. Access point according to claim 2, wherein said optimum channel is determined as being the channel having the minimum sum of said channel interference parameter and said channel sharing parameter.

6. Access point according to claim 2, wherein said optimum channel is determined as being part of a set of channels having sums of said channel interference parameter and said channel sharing parameter, wherein said sums are within a predefined distance δ

from the minimum sum, and wherein said optimum channel has the largest channel sharing parameter of the channels in said set.

7. Access point according to claim 1, wherein said channel interference parameter, during on-time, is defined as CI(j) with:

8. Access point according to claim 2, wherein said channel sharing parameter, during on-time, is defined as CS(j) with:

9. Access point according to claim 1, wherein said access point monitors its current channel during normal operation, in order to calculate an average disturbance AV_dist, wherein said access point switches to said optimum channel if said calculated average disturbance exceeds a disturbance threshold K_dist for allowable disturbance, wherein:

10. Access point according to claim 1, wherein said access point is arranged to determine its load and to use a longer scanning time when the load becomes lower and vice versa.

11. Communication system comprising an access point according to claim 1.

13. Method according to claim 10, wherein the following steps are carried out:

additionally storing, in step (c), a channel sharing parameter indicative of a time period in said scanning time that said level of sharing exceeded a second threshold;

in step (e), selecting said optimum channel in accordance with said predetermined rule taking said channel interference parameter and said channel sharing parameter into account.

12. Method of dynamically selecting an optimum channel by an access point for a wireless communication network, comprising a processor and memory storing data and instructions, comprising the following steps:

(a) selecting a channel from a plurality of possible channels;

(b) collecting data as to at least level of interference on said channel during a predetermined scanning time;

(c) storing a channel interference parameter indicative of a time period in said scanning time that said level of interference exceeded a first threshold value;

(d) repeating steps (b) and (c) for all other channels of said plurality of channels;

(e) selecting said optimum channel in accordance with a predetermined rule taking said channel interference parameter into account.

14. Computer program product for dynamically selecting an optimum channel by an access point of a wireless communication network, comprising a processor and memory for storing data and instructions, said computer program product after being loaded providing said access point with the following functionality:

(a) selecting a channel from a plurality of possible channels;

(b) collecting data as to at least level of interference on said channel during a predetermined scanning time;

(c) storing a channel interference parameter indicative of a time period in said scanning time that said level of interference exceeded a first threshold value;

(d) repeating steps (b) and (c) for all other channels of said plurality of channels;

(e) selecting said optimum channel in accordance with a predetermined rule taking said channel interference parameter into account.

15. Data carrier provided with a computer program product according to claim 14.