Methods and apparatus for derivative-based optimization of wireless network performance

• US 6,611,500 B1
• Filed: 11/04/1999
• Issued: 08/26/2003
• Est. Priority Date: 11/04/1999
• Status: Expired due to Fees

• Current Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Hobby, John D., Hampel, Karl Georg, Polakos, Paul Anthony, Clarkson, Kenneth L.
• Primary Examiner(s): Chin, Wellington
• Assistant Examiner(s): FOX, JAMAL A
• Application Number:
  US09/434,578
• Time in Patent Office: 1,391 Days
• Field of Search: 370/252, 370/335, 370/254, 713/201, 709/227, 705/20, 455/67.1, 455/67.6, 455/436, 455/446, 455/449, 455/453
• US Class Current: 370/252
• CPC Class Codes: H04W 16/18 Network planning tools

Abstract

Improved techniques for optimizing performance of a wireless network. In an illustrative embodiment, a derivative-based optimization process is applied to optimize an objective function of a network performance metric with respect to a number of network tuning parameter variables. The optimization may be based on first or higher order derivatives of the objective function with respect to the selected network parameter variables. The objective function may include, e.g., one or more of a maximization of network coverage, a maximization of network capacity, and a minimization of network resources. Additional network parameters which are not variables in optimization process serve as constraints to the optimization process. Advantageously, the invention substantially improves the process of designing, adjusting and optimizing the performance of wireless networks.

Claims

1. A processor-implemented method for providing a desired level of performance in a wireless cellular network comprising a plurality of cells each having an associated base station, the method comprising the steps of:

selecting one or more network parameters associated with an air interface of the wireless cellular network as variables; and

optimizing an objective function of the wireless cellular network over multiple ones of the plurality of cells based on first or higher order derivatives of the objective function with respect to the selected network parameter variables.

2. The method of claim 1 wherein one or more of the selected network parameters are characterized by continuous functions.

3. The method of claim 1 wherein the optimizing step utilizes an optimization algorithm to implement the optimization based on first or higher order derivatives of the objective function with respect to the selected network parameter variables.

4. The method of claim 1 wherein the objective function comprises at least one of:

(i) a maximization of network coverage, (ii) a maximization of network capacity, and (iii) a minimization of network resources.

5. The method of claim 4 wherein the objective function comprises a linear combination of at least two of:

(i) the maximization of network coverage, (ii) the maximization of network capacity, and (iii) the minimization of network resources.

6. The method of claim 4 wherein network coverage is defined at least in part as a fraction of area in which quality of service is above a specified threshold, with respect to a target coverage area.

7. The method of claim 6 wherein network coverage is weighted in accordance with a weighting factor representative of traffic density within a particular coverage area.

8. The method of claim 4 wherein network capacity is defined at least in part by an amount of traffic having a given spatial distribution, and represents the ability of the wireless network to match the spatial traffic distribution.

9. The method of claim 8 wherein network capacity component further represents the amount of traffic having the given spatial distribution that can be carried by the network with a specified target blocking rate.

10. The method of claim 1 wherein the selected network parameters comprise at least one antenna parameter including at least one of antenna location, antenna height, antenna orientation, antenna tilt, and antenna beamwidth.

11. The method of claim 1 wherein the selected network parameters comprise a transmit power level for at least one communication channel and link of the wireless system.

12. The method of claim 1 wherein the selected network parameters comprise a handoff threshold for at least one communication channel and link of the wireless system.

13. The method of claim 1 wherein the selected network parameters comprise a number of channel units per cell or cell sector of the wireless system.

14. The method of claim 1 wherein the selected network parameters comprise a scaling factor for a power amplifier of the wireless system.

15. The method of claim 1 wherein additional network parameters which are not variables in optimization process serve as constraints to the optimization process.

16. The method of claim 1 wherein the optimizing step utilizes a propagation environment model based on statistical path loss.

17. The method of claim 1 wherein the optimizing step utilizes at least one of predicted propagation data and actual propagation data determined from in-field measurements.

18. The method of claim 1 wherein the wireless network comprises a network which supports mobile wireless subscriber units.

19. The method of claim 1 wherein the wireless network comprises a network which supports fixed wireless subscriber units.

20. An apparatus for providing a desired level of performance in a wireless cellular network comprising a plurality of cells each having an associated base station, the apparatus comprising:

a processor-based system operative (i) to identify one or more network parameters associated with an air interface of the wireless cellular network as variables; and

(ii) to optimize an objective function of the wireless cellular network over multiple ones of the plurality of cells based on first or higher order derivatives of the objective function with respect to the selected network parameter variables.

21. An article of manufacture comprising a computer-readable medium storing one or more software programs for use in providing a desired level of performance in a wireless cellular network comprising a plurality of cells each having an associated base station, wherein the one or more programs when executed by a processor include:

selecting one or more network parameters associated with an air interface of the wireless cellular network as variables; and

optimizing an objective function of the wireless cellular network over multiple ones of the plurality of cells based on first or higher order derivatives of the objective function with respect to the selected network parameter variables.