System and method for identifying a source of interference in a mobile telecommunications network

• US 6,393,277 B1
• Filed: 08/13/1999
• Issued: 05/21/2002
• Est. Priority Date: 08/13/1999
• Status: Expired due to Term

• Current Assignee: Ericsson, Inc. (Telefonaktiebolaget LM Ericsson)
• Original Assignee: Ericsson, Inc. (Telefonaktiebolaget LM Ericsson)
• Inventors: Sahin, Yildirim, Shah, Ali, Yost, George P.
• Primary Examiner(s): Trost, William
• Assistant Examiner(s): GESESSE, TILAHUN
• Application Number:
  US09/374,718
• Time in Patent Office: 1,012 Days
• Field of Search: 455/63, 455/423, 455/424, 455/425, 455/453, 455/446, 455/447, 455/448, 455/449, 455/67-1, 455/67.3, 455/67.7, 455/226.1, 455/226.2, 455/226.3, 370/329, 370/331, 370/332, 370/130
• US Class Current: 455/423
• CPC Class Codes: H04W 16/18 Network planning tools

Abstract

A method and system are disclosed for identifying one or more sources of co-channel interference within a selected cell in a mobile telecommunications network. The system includes data collecting devices which measure and store interference levels within the selected sell and traffic levels within a plurality of candidate cells, any of which may potentially contribute to the interference. The system further includes a processing element which, for each candidate cell, determines a partial correlation coefficient between the stored interference levels and the stored traffic levels for the candidate cell. The processing element additionally determines the multiple correlation coefficient between the stored interference levels and the stored traffic levels for all of the candidate cells. Based upon the partial and multiple correlation coefficients, the processing element is capable of accurately identifying the candidate cells which contribute to the co-channel interference in the selected cell.

Claims

1. A method of identifying a source of interference associated with a selected cell in a mobile telecommunications network, comprising the steps of:

identifying candidate cells in the mobile telecommunications network, at least one of which is a source of interference within the selected cell;

measuring interference levels within the selected cell during predetermined sampling intervals and storing at least one interference level for each sampling interval in memory;

measuring traffic levels within candidate cells during the predetermined sampling intervals and, for each candidate cell, storing at least one traffic level for each sampling interval in memory;

for each candidate cell, determining a partial correlation coefficient between the stored interference levels and the stored traffic levels for the candidate cell; and

identifying one or more interfering candidate cells that cause the interference within the selected cell, based upon the determined partial correlation coefficients.

2. The method of claim 1, wherein:

said step of identifying candidate cells identifies cells in the mobile telecommunications network within which information is communicated at a frequency that is the same as the frequency at which information within the selected cell is communicated.

3. The method of claim 1, further comprising the step of:

determining the multiple correlation coefficient between the stored interference levels and the stored traffic levels corresponding to all of the candidate cells.

4. The method of claim 3, wherein:

said step of identifying the one or more interfering candidate cells identifies the one or more interfering candidate cells based upon the determined multiple correlation coefficient.

5. The method of claim 1, further comprising the step of:

identifying the candidate cell that provides the most interference within the selected cell.

6. The method of claim 5, wherein said step of identifying the candidate cell providing the most interference comprises the steps of:

for each candidate cell, determining a simple correlation coefficient between the stored interference levels and the stored traffic levels for the candidate cell; and

identifying the candidate cell associated with the greatest simple correlation coefficient as the candidate that provides the most interference within the selected cell.

7. The method of claim 1, wherein the step of determining a partial correlation coefficient for each candidate cell comprises the step of:

creating a covariance matrix based upon the stored interference levels and the stored traffic levels.

8. In a mobile cellular telecommunications system, an apparatus for identifying a source of interference associated with a selected cell from one or more candidate cells, comprising:

a memory device;

a plurality of data collecting devices for measuring interference levels within the selected cell during predetermined sampling intervals and storing at least one interference level for each sampling interval in said memory device, and for measuring traffic levels within said candidate cells during the predetermined sampling intervals and storing at least one traffic level of each candidate cell for each sampling interval in said memory device; and

a processing element, in communication with said memory device, for determining, for each said candidate cell, a partial correlation coefficient between the stored interference levels and the stored traffic levels for the candidate cell, and for identifying one or more interfering candidate cells that cause the most interference within the selected cell, based upon the determined partial correlation coefficients.

9. The apparatus of claim 8, wherein:

for each candidate cell, said processing element determines a simple correlation coefficient between the stored interference levels and the stored traffic levels for the candidate cell, and identifies the candidate cell that provides the most interference to the selected cell based upon the simple correlation coefficients.

10. The apparatus of claim 9, wherein:

said processing element identifies the candidate cell associated with the greatest simple correlation coefficient as the candidate cell that provides the most interference to the selected cell.

11. The apparatus of claim 8, wherein:

said processing element determines a multiple correlation coefficient between the stored interference levels and the stored traffic levels, and identifies said one or more interfering candidate cells based upon the multiple correlation coefficient.

12. A method of identifying a source of interference associated with a selected cell in a mobile telecommunications network, comprising the steps of:

identifying candidate cells in the mobile telecommunications network, at least one of which is a source of interference within the selected cell;

measuring interference levels within the selected cell during predetermined sampling intervals and storing at least one interference level for each sampling interval in memory;

measuring traffic levels within candidate cells during the predetermined sampling intervals and, for each candidate cell, storing at least one traffic level for each sampling interval in memory;

for each candidate cell, determining a correlation coefficient between the stored interference levels and the stored traffic levels for the candidate cell; and

identifying the candidate cell that causes the greatest amount of interference within the selected cell, based upon the determined correlation coefficients.

13. The method of claim 12, wherein:

said step of determining a correlation coefficient comprises the step of determining, for each candidate cell, a simple correlation coefficient correlating the stored interference levels and the stored traffic levels for the candidate cell.

14. The method of claim 12, wherein:

said step of determining a correlation coefficient comprises the step of determining, for each candidate cell, a partial correlation coefficient correlating the stored interference levels and the stored traffic levels for the candidate cell; and

said method further comprises the step of identifying other candidate cells that cause interference within the disturbed cell, based upon the determined partial correlation coefficients.