Method and apparatus for design of wireless networks to aid in location identification of mobile units

• US 20040259522A1
• Filed: 06/17/2003
• Published: 12/23/2004
• Est. Priority Date: 06/17/2003
• Status: Active Grant

• Current Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Alicherry, Mansoor Ali Khan, Poosala, Viswanath, Nagesh, Harsha, Phadke, Chitra
• Granted Patent: US 7,099,670 B2
• Time in Patent Office: Days
• US Class Current: 455/404.2
• CPC Class Codes: H04W 4/02 Services making use of location information
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

Techniques and systems for designing a network providing communication and location identification services are described. A solution point comprising parameters for each of a plurality of base stations is generated. A coverage and locatability performance value for the solution point is computed, as well as derivatives of the performance value. The coverage and locatability performance value and its derivatives are used to indicate favorable directions for searching for subsequent solution points, and subsequent solution points are generated and compared against previous solution points until an optimum solution point is found. The coverage and locatability performance value is a weighted sum of coverage and locatability values for each point in the service area of the network, with coverage values representing forward and reverse link quality and locatability values representing the probability that a point will experience an acceptable power level from at least four base stations.

Claims

1. A system for design of a wireless network providing communication and location services for mobile units within the service area of the network, comprising:

an optimizer for generating solution values for a network design, the optimizer being operative to search for solution points providing optimal communication coverage and location identification performance for the network; and

a coverage and locatability engine for evaluating coverage and location performance for each of a series of solution points selected by the optimizer, the coverage and locatability engine computing a coverage and locatability performance value for each of the solution points and providing the performance value to the optimizer for use in evaluating the quality of the solution point.

2. The system of claim 1, wherein the optimizer searches for candidate solution points by first generating an initial candidate solution point, submitting the initial candidate solution point to the coverage and locatability engine for evaluation and using the results generated by the coverage and locatability engine to evaluate the quality of the solution point and to determine favorable search areas for the next solution point, and repeatedly generating and evaluating new candidate solution points until an optimal solution point is found.

3. The system of claim 2, wherein the coverage and locatability engine computes derivatives of each coverage and locatability performance value for a solution point and wherein the derivatives are used by the optimizer to indicate favorable directions in which to search for a new candidate solution point.

4. The system of claim 3, wherein the optimizer, upon identifying a candidate solution point, perturbs the parameters of the solution point in order to identify the most favorable solution in the solution space in the vicinity of the candidate solution point.

5. The system of claim 4, wherein the coverage and locatability performance value is a weighted sum of coverage and locatability values for each point within the network.

6. The system of claim 5, wherein the coverage value for each point within the network is based on the quality of the forward and reverse link for the mesh point and wherein the value for locatability for each point within the network is based on the likelihood that the mesh point will experience a forward link of at least a specified minimum power for at least four different base stations in the service area.

7. The system of claim 6, wherein the optimizer receives terrain and traffic information for use in computing the solution points.

8. The system of claim 7, wherein each solution point comprises values for the power, azimuth angle and tilt angle for each base station antenna in the network.

9. The system of claim 8, further including a history database for storing each candidate solution point and details of the computation and evaluation of each candidate solution point, for use in determining whether an optimal solution point has been generated.

10. A method of design for a network providing communication and location identification services for mobile units, comprising the steps of:

receiving terrain and traffic information for a network;

sequentially generating a series of solution points for the network;

evaluating the coverage and locatability performance of each solution point and comparing each subsequently computed solution point with the previously computed solution point to determine if the subsequently computed solution point represents an improvement;

retaining the subsequently computed solution point if it represents an improvement over the previously computed solution point and discarding the subsequently computed solution point otherwise; and

continuing to generate and evaluate solution points until an optimal solution point is found.

11. The method of claim 10, wherein the step of evaluating the coverage and locatability performance of each solution point includes examining the results of the evaluation to identify favorable search directions for use in generating a subsequent solution point.

12. The method of claim 11, wherein the step of evaluating the coverage and locatability performance of each solution point includes computing coverage and locatability values for each point in the service area of the network and computing a weighted sum of the coverage and locatability values in order to generate a coverage and locatability performance value for the solution point.

13. The method of claim 12, wherein the coverage value for each point in the service area includes an evaluation of the forward and reverse link power for the point and wherein the locatability value for each point includes an evaluation of the probability that the point will experience at least a minimum threshold power from at least four base stations.

14. The method of claim 13, wherein each solution point comprises values for power, azimuth angle and tilt angle for each base station antenna in the network.

15. A software program for design of wireless networks providing communication and locatability services and executable by a data processing system, comprising:

an optimizer module for generating solution values for a network design, the optimizer being operative to search for solution points providing optimal communication coverage and location identification performance for the network; and

a coverage and locatability module for evaluating coverage and location performance for each of a series of solution points selected by the optimizer, the coverage and locatability engine computing a coverage and locatability performance value for each of the solution points and providing the performance value to the optimizer for use in evaluating the quality of the solution point.

16. The software program of claim 15, wherein the optimizer module searches for candidate solution points by first generating an initial candidate solution point, submitting the initial candidate solution point to the coverage and locatability module for evaluation and using the results generated by the coverage and locatability module to evaluate the quality of the solution point and to determine favorable search areas for the next solution point, and repeatedly generating and evaluating new candidate solution points until an optimal solution point is found.

17. The software program of claim 16, wherein the coverage and locatability module computes derivatives of each coverage and locatability performance value for a solution point and wherein the derivatives are used by the optimizer to indicate favorable directions in which to search for a new candidate solution point.

18. The software program of claim 17, wherein the optimizer module, upon identifying a candidate solution point, perturbs the parameters of the solution point in order to identify the most favorable solution in the solution space in the vicinity of the candidate solution point.

19. The software program of claim 18, wherein the coverage and locatability performance value is a weighted sum of coverage and locatability values for each point within the network.

20. The software program of claim 19, wherein the coverage value for each point within the network is based on the quality of the forward and reverse link for the mesh point and wherein the value for locatability for each point within the network is based on the likelihood that the mesh point will experience a forward link of at least a specified minimum power for at least four different base stations in the service area.