Frequency assignment for multi-cell IEEE 802.11 wireless networks

• US 7,346,357 B1
• Filed: 03/13/2007
• Issued: 03/18/2008
• Est. Priority Date: 11/08/2001
• Status: Expired due to Fees

• Current Assignee: AT&T Corporation (AT&T, Inc.)
• Original Assignee: AT&T Corporation (AT&T, Inc.)
• Inventors: Kim, Byoung-Jo J., Leung, Kin K
• Primary Examiner(s): Gelin; Jean
• Assistant Examiner(s): Nguyen; Huy D
• Application Number:
  US11/717,366
• Time in Patent Office: 371 Days
• Field of Search: 455/453, 455/446, 455/447, 455/450, 455/451, 455/452.1
• US Class Current: 455/453
• CPC Class Codes: H04W 16/04 Traffic adaptive resource partitioning
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 28/16 Central resource management; Negotiation of resources or communication parameters, e.g. negotiating bandwidth or QoS [Quality of Service]
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]

Abstract

A frequency planning method for use in an IEEE 802.11 wireless network is described. The frequency planning method obtains traffic load information associated with access points belonging to a multi-cell wireless network and assigns channels to the access points based on the traffic load information.

Claims

1. A method executed in a network management system adapted to work with a network of access points AP_i, i=1, 2, . . . M, where each AP_i communicates at an assigned frequency with a plurality of terminals, and where the communication between an access point and a terminal employs a protocol that provides contention-based access using a carrier sense multiple access with collision avoidance (CDMA/CA) mechanism, and also provides contentions-free access when the contention-based access is successful, comprising the steps of:

receiving from each APi information about (a) fraction of time that APi is busy, (b) for each possible frequency of operation, k, fraction of time that one or more access points other than APi would interfere with APi if APi were communicating at frequency k, and (c) for each possible frequency of operation, k, fraction of time that one or more pairs of access points, not including APi, would interfere with APi if APi were communicating at frequency k;

developing a measure of effective channel utilization for APi, Ui, operating at frequency l, in accord with the expression

2. The method of claim 1 where the objective function is

min max {U₁, U₂, . . . , U_M},

and the minimization is carried out over the assignment indicator X_rk, subject to the constraint that no effective channel utilization by an access point exceeds the total capacity of the access point.

3. The method of claim 1 where the step of creating employs a heuristic algorithm.

4. The method of claim 3 where the algorithm begins with a random channel assignment.

5. The method of claim 4 where, in said algorithm,

(a) effective channel utilizations for each access point is computed,

(b) identify the highest effective channel utilization is, V, the access point with that highest effective channel utilization (AP_highest), and the frequency assigned to AP_highest,

(c) assign all other possible other frequencies, one at a time, to AP_highest, for each assignment re-compute the effective channel utilizations for each access point,

(d) identify, following the re-computing, the a channel assignment with the lowest effective channel utilization, W;

(e) if W is less than V, replace V with W and return to step (c), and if W is not less than V, retain V.