Method of evaluation of the effect of channel reassignment and/or parameter changes on interference throughout a cellular system

• US 6,496,698 B2
• Filed: 06/15/2001
• Issued: 12/17/2002
• Est. Priority Date: 07/02/1997
• Status: Expired due to Fees

• Current Assignee: Allen Telecom LLC (CommScope Holding Company, Inc.)
• Original Assignee: Scoreboard Inc. (CommScope Holding Company, Inc.)
• Inventors: Jensen, Eric
• Primary Examiner(s): Hunter, Daniel
• Assistant Examiner(s): TRAN, PABLO N
• Application Number:
  US09/882,478
• Publication Number:
  US 20020022480A1
• Time in Patent Office: 550 Days
• Field of Search: 455/446-447, 455/423, 455/450, 455/524-525, 455/33.1, 455/33.4, 455/39.1, 455/67.1, 455/67.3, 455/67.7, 455/226--22, 455/134-135, 455/62-63, 455/422, 455/403
• US Class Current: 455/447
• CPC Class Codes: H04W 16/18 Network planning tools

Abstract

A computer implemented process compares signals communicated between a known position and a plurality of base stations in a cellular telephone system to determine the level of interference with a signal on a channel expected to serve the known position, and determines a value indicating a probability of interference with a signal on a channel expected to serve the known position.

Claims

1. A method for evaluating the effect of channel reassignment and/or a change in parameter settings on the interference quality in a cellular system, wherein said cellular system being evaluated may be an entire cellular system or a portion of a cellular system, comprising the steps of:

identifying a plurality of likely servers for a plurality of corresponding known positions in a cellular telephone system;

comparing additional signals received at said plurality of known positions in said cellular telephone system to determine the potential interference of each of said additional signals with said plurality of likely servers; and

determining a quality value for each of said likely servers at each of said corresponding known positions, based upon the interactive probability of interference from said additional signals, for a first set of planned channel assignments and parameter settings;

dividing said cellular system into a plurality of sectors, each of said sectors including a plurality of said known positions;

determining an interference quality value for each of said sectors based upon the quality values for the known positions within each of said sectors;

determining a first quality score for said cellular system based upon said interference quality values for said sectors of said cellular system;

determining the effect on said potential interference from one or more of said additional signals which would occur as a result of changing one or more parameters and/or channel assignments of one or more of said additional signals;

redetermining said quality values for each of said known positions effected by said change in said additional signals;

redetermining said sector interference quality values for each sector effected by said redetermination of said quality vales for said each of said known positions;

determining a second cellular system interference quality score based upon said redetermined sector interference quality values; and

evaluating the system interference score quality effect of said changes by comparison of said first system interference quality score with said second system interference quality score.

2. A process for optimizing the performance of a wireless communication system, comprising the steps of:

for each of a number of measurement points within the bounds of a test region;

determining a likely server sector based upon the relative values of a number of signal strength measurements made at said measurement point;

determining a number of likely interferer sectors based upon the relative values of said number of signal strength measurements made at said measurement point; and

for each individual one of said likely interferer sectors, calculating a value obtained from an estimate of said individual sector'"'"'s likelihood of transmission and the relative value of said individual sector'"'"'s signal strength measurement to said likely server sector'"'"'s signal strength measurement;

determining a weighted probability that at least one of said number of likely interferer sectors will be active at some time, from said calculated values; and

ascribing said weighted probability as a magnitude of measurement point interference.

3. The process of claim 2, further comprising the step of:

for each individual one of a number of server sectors within the bounds of said test region, determining an individual sector interference value by;

calculating a sector interference value from said measurement point interference values for all of said number of measurement points having a common likely server sector.

4. The process of claim 3, further comprising the step of:

determining a system interference score from;

calculating a system interference sum by summing said individual sector interference values for all of said number of server sectors within the bounds of said test region.

5. The process of claim 3, further comprising the steps of:

ascribing said sector interference value as a sector current quality value;

correlating each of said number of signal measurements with a corresponding and separate conceptual signal that represents the characteristics of said measured signal within a propagation model;

changing a value of one of a number of parameters associated with one of said number of conceptual signals;

applying said propagation model to said number of conceptual signals to determine the expected signal strengths of said number of conceptual signals at each of said number of signal measurement points;

revising said individual sector interference value by substituting said expected signal strength values for said corresponding signal strength measurement values;

comparing said revised individual sector interference value to said sector current quality value; and

associating a quality increment value with said revised individual sector interference value that indicates a relative value of an improvement, provided by said parameter value change, over said sector current quality.

6. The process of claim 5, further comprising the steps of:

performing the steps identified in claim 5 for a plurality of different values of said one of a number of parameters, as applied to said one conceptual signal;

identifying which parameter value of said plurality of different values provides the greatest quality increment value; and

ascribing said identified parameter value and its associated quality increment value to a signal best change vector associated with said one of said conceptual signals.

7. The process of claim 6, further comprising the steps of:

performing the steps of claim 6 on a number of different conceptual signals;

identifying which of said signal best change vectors, each associated with a different one of said number of conceptual signals, provides the greatest quality increment value; and

ascribing said identified signal best change vector value and its associated quality increment value to a sector best change vector associated with said one of said number of parameters.

8. The process of claim 7, further comprising the steps of:

performing the steps of claim 7 on a number of different parameters of said number of parameters;

identifying which of said sector best change vectors, each associated with a different one of said number of different parameters, provides the greatest quality increment value; and

ascribing said identified sector best change vector value and its associated quality increment value to a multi-parameter best change vector.

9. The process of claim 4, further comprising the steps of:

ascribing said system interference score as a system current quality score;

correlating each of said number of signal measurements with a corresponding and separate conceptual signal that represents the characteristics of said measured signal within a propagation model;

changing a value of one of a number of parameters associated with one of said number of conceptual signals;

applying said propagation model to said number of conceptual signals to determine the expected signal strengths of said number of conceptual signals at each of said number of signal measurement points;

revising said individual system interference score by substituting said expected signal strength values for said corresponding signal strength measurement values;

comparing said revised individual system interference score to said system current quality score; and

associating a quality increment value with said revised individual system interference score that indicates a relative value of an improvement, provided by said parameter value change, over said system current quality score.

10. The process of claim 9, further comprising the steps of:

performing the steps identified in claim 9 for a plurality of different values of said one of a number of parameters, as applied to said one conceptual signal;

identifying which parameter value of said plurality of different values provides the greatest quality increment value; and

ascribing said identified parameter value and its associated quality increment value to a signal best change vector associated with said one of said conceptual signals.

11. The process of claim 10, further comprising the steps of:

performing the steps of claim 10 on a number of different conceptual signals;

identifying which of said signal best vectors, each associated with a different one of said number of conceptual signals, provides the greatest quality increment value; and

ascribing said identified signal best vector value and its associated quality increment value to a system best change vector associated with said one of said number of parameters.

12. The process of claim 11, further comprising the steps of:

performing the steps of claim 11 on a number of different parameters of said number of parameters;

identifying which of said system best vectors, each associated with a different one of said number of different parameters, provides the greatest quality increment value; and

ascribing said identified system best vector value and its associated quality increment value to a multi-parameter best change vector.

13. The process of claim 8, wherein:

said number of different parameters consists of the parameters of signal frequency, signal power, and hand-off biasing level.

14. The process of claim 12, wherein:

said number of different parameters consists of the parameters of signal frequency, signal power, and hand-off biasing level.