Cell radius estimation method

• US 6,173,186 B1
• Filed: 11/04/1998
• Issued: 01/09/2001
• Est. Priority Date: 08/27/1998
• Status: Expired due to Fees

• Current Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Original Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Inventors: Dalley, James Edward
• Primary Examiner(s): Eisenzopf, Reinhard J.
• Assistant Examiner(s): APPIAH, CHARLES NANA
• Application Number:
  US09/185,933
• Time in Patent Office: 797 Days
• Field of Search: 455/446, 455/422, 455/67.6, 455/561, 455/562, 455/423, 342/458
• US Class Current: 455/446
• CPC Class Codes: H04W 16/18 Network planning tools

Abstract

Current radio telecommunications cell radius estimation methods can result in spurious and inaccurate results outside regions with well sampled signal measurements. The present invention provides an improved cell radius estimation method using path loss and signal source distance data as well as a method for determining models for use in cell estimation without test data. The methods apply a fixed gradient line fit to the data to obtain cell radius estimates and to determine models for one or more geomorphology classifications. Cell radius estimates determined from the test data and the models can be used for cell distribution planning in network coverage planning applications. The invention provides improved accuracy as well as reduced costs in the network planning stage.

Claims

1. A method for estimating the radius of a radio telecommunications cell comprising the steps of:

determine path loss and range data from a plurality of predetermined locations within said cell;

apply a predetermined gradient line fit to said data;

obtain from said line fit a radius estimate for said cell corresponding to a predetermined signal level.

2. A method as claimed in claim 1 wherein the predetermined gradient line fit is determined according to the equation:

3. A method as claimed in claim 2 wherein the predetermined gradient is dependent on the height of the base station antenna.

4. A method as claimed in claim 3 wherein the predetermined gradient is determined from the Hata path loss model.

5. A method as claimed in claim 1 comprising the additional step of:

removing determined data less than a predetermined range.

6. A method as claimed in claim 1 comprising the additional step of:

removing determined data having a signal level below a predetermined signal floor level.

7. A method as claimed in claim 1 comprising the additional step of:

removing determined data with a range over which the average signal level is within a predetermined signal difference level of a predetermined signal floor level.

8. A method as claimed in claim 7, wherein the predetermined signal difference level corresponds to two standard deviations of the average signal level at said range.

9. A method as claimed in claim 1 comprising the additional step of:

removing determined data having a path loss less than a theoretical minimum path loss.

10. A method as claimed in claim 1 comprising the additional step of:

removing determined data having a signal level above a predetermined maximum signal level.

11. A method as claimed in claim 1 comprising the additional step of:

removing determined data having a path loss differing from other determined data at substantially the same range by an amount greater than a predetermined path loss difference.

12. A method of determining models for radio telecommunications cell radius estimation comprising the steps of:

determine path loss and range data from a plurality of predetermined locations within each of a plurality of cells;

classify each cell according to geomorphology;

for each cell apply a predetermined gradient line fit to said data and determine a path loss intercept at a predetermined range;

for each classification add said intercept values for each cell together with a corresponding base station height to a database, apply a line fit to said database data to obtain a model of path loss intercept values versus base station antenna height for use in the estimation of cell radii for cells of a selected base station height and geomorphology classification.

13. A method for estimating the radius of a radio communications cell comprising the steps of:

determine the path loss intercept value for a selected base station height and geomorphology from a model determined by;

a method of determining models for radio telecommunications cell radius estimation comprising the steps of;

determine path loss and range data from a plurality of predetermined locations within each of a plurality of cells;

classify each cell according to geomorphology;

for each cell apply a predetermined gradient line fit to said data and determine a path loss intercept at a predetermined range;

for each classification add said intercept values for each cell together with a corresponding base station height to a database, apply a line fit to said database data to obtain a model of path loss intercept values versus base station antenna height for use in the estimation of cell radii for cells of a selected base station height and geomorphology classification;

apply a predetermined gradient line fit to the intercept; and

obtain from said line fit a radius estimate for said cell corresponding to a predetermined signal level.

14. A method of determining radio telecommunications cell radius estimates for planning a cellular network coverage area comprising the steps of:

divide the network coverage area into a plurality of cells;

for a predetermined percentage of said cells determine cell radius estimates according to;

a method for estimating the radius of a radio telecommunications cell comprising the steps of;

determine path loss and range data from a plurality of predetermined locations within said cell;

apply a predetermined gradient line fit to said data;

obtain from said line fit a radius estimate for said cell corresponding to a predetermined signal level;

and, for the remaining percentage of cells determine cell radius estimates according to;

a method for estimating the radius of a radio communications cell comprising the steps of;

determine the path loss intercept value for a selected base station height and geomorphology from a model determined by;

a method of determining models for radio telecommunications cell radius estimation comprising the steps of;

determine path loss and range data from a plurality of predetermined locations within each of a plurality of cells;

classify each cell according to geomorphology;

for each cell apply a predetermined gradient line fit to said data and determine a path loss intercept at a predetermined range;

for each classification add said intercept values for each cell together with a corresponding base station height to a database, apply a line fit to said database data to obtain a model of path loss intercept values versus base station antenna height for use in the estimation of cell radii for cells of a selected base station height and geomorphology classification;

apply a predetermined gradient line fit to the intercept; and

obtain from said line fit a radius estimate for said cell corresponding to a predetermined signal level.