System and method for identifying interferes in a communication spectrum

• US 7,133,686 B2
• Filed: 01/08/2003
• Issued: 11/07/2006
• Est. Priority Date: 01/08/2003
• Status: Active Grant

• Current Assignee: VTech Telecommunications Limited (VTech Holdings Ltd.)
• Original Assignee: VTech Telecommunications Limited (VTech Holdings Ltd.)
• Inventors: Koprivica, Milosh, Hundal, Sukhdeep S.
• Primary Examiner(s): Gesesse, Tilahun
• Application Number:
  US10/338,011
• Publication Number:
  US 20040132410A1
• Time in Patent Office: 1,399 Days
• Field of Search: 455/426.1, 455/426.2, 455/67.11, 455/67.14, 455/67.7, 455/226.1, 455/226.2, 455/465, 455/1
• US Class Current: 455/465
• CPC Class Codes: H04B 17/0085 using test signal generators
• CPC Class Codes: H04B 17/318 Received signal strength
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements

Abstract

A method for identifying interferers in a radio communication band, such as the 2.4 GHz ISM band, uses a priori information of the interferers such as channel structure, channel frequency and channel bandwidth. Measured RSSI can be used to detect and identify interferers. RSSI measurements can be made at multiple frequencies within a channel of the interferer. Randomization of RSSI measurements improves the likelihood of interferer detection and identification if such interferer is present. Metrics other than RSSI can be used.

Claims

1. A method for identifying an interferer in a cordless telephone communication band, comprising:

selecting N channels characteristics of the interferer;

selecting a plurality of frequencies within each of the selected N channels;

measuring a power spectral density in a bandwidth where the interferer is expected by measuring an RSSI at each of the selected frequencies within each of the selected N channels and calculating a function value dependent upon the measured RSSIs at each of the selected frequencies; and

identifying the interferer if the function value exceeds a threshold in accordance with the measured power spectral density.

2. The method recited claim 1, further comprising selecting frequencies for measuring RSSI independent of previous measurements.

3. The method recited in claim 1, further comprising measuring RSSI for all selected plurality of frequencies in one channel prior to measuring RSSI for any frequency in another channel.

4. The method recited in claim 1, further comprising measuring RSSI for any frequency in any channel regardless of whether RSSI has been measured for all selected plurality of frequencies in a particular channel.

5. The method recited in claim 1, further comprising measuring RSSIs substantially simultaneously.

6. The method recited in claim 1, further comprising not measuring RSSIs substantially simultaneously.

7. The method recited in claim 1, wherein the threshold is predetermined.

8. The method recited in claim 1, wherein the threshold is dynamically adjustable.

9. A cordless telephone system for identifying an interferer in a cordless telephone communication band, comprising:

a handset comprising;

a receiver to receive a signal at a particular frequency, the frequency determined using one or more known characteristics of the interferer;

a signal conditioning unit to process and digitize the signal;

a memory to store the digitized signal;

a first microprocessor to measure a power spectral density in a bandwidth where the interferer is expected and to identify the interferer in accordance with the measured power spectral density; and

a base unit in communication with the handset, wherein the base unit comprises;

a receiver to receive a signal at a second particular frequency, the frequency determined using one or more known characteristics of the interface;

a signal conditioning unit to process and digitize the signal;

a memory to store the digitized signal; and

a second microprocessor to measure a power spectral density in a bandwidth where the interferer is expected and to identify the interferer in accordance with the measured power spectral density.

10. The cordless telephone system recited in claim 9, wherein the first microprocessor is further configured to measure an RSSI at the particular frequency, compare the RSSI to a threshold, and identify the interferer if the RSSI exceeds the threshold.

11. The cordless telephone system recited in claim 9, wherein the second microprocessor is further configured to measure an RSSI at the second particular frequency, compare the RSSI to the threshold and identify the interferer if the RSSI exceeds the threshold.

12. A method for identifying an interferer in a radio communication band, said method comprising:

selecting a plurality of test channels in accordance with a channel structure of the interferer;

selecting a frequency in each selected channel;

measuring a power spectral density in a bandwidth where the interferer is expected by measuring an RSSI at the selected frequency in each selected channel and calculating a function value dependent upon the measured RSSIs at the selected frequency;

identifying the interferer in accordance with the measured power spectral density.

13. The method recited in claim 12, further comprising

comparing the shape of the measured power spectral density with shapes of power spectral densities for known interferers;

and

determining if there is a match in shape.

14. The method recited in claim 12, further comprising measuring the power spectral density by estimating the power spectral density using a plurality of narrowband RSSI measurements.

15. The method recited in claim 14, further comprising randomizing the RSSI measurements.

16. The method recited in claim 14, further comprising varying a time of the RSSI measurements.

17. The method recited in claim 12, further comprising:

measuring an RSSI associated with the selected frequency in each selected channel; and

comparing each measured RSSI to a threshold; and

identifying the interferer in accordance with the measured RSSI.

18. The method recited in claim 17, further comprising:

determining a percentage of measured RSSIs that exceed the threshold; and

comparing the percentage to an RSSI channel percentage threshold.

19. The method recited in claim 17, further comprising:

selecting at least one additional frequency in each selected channel; and

measuring an RSSI corresponding to each additional selected frequency.

20. The method recited in claim 19, further comprising:

comparing each measured RSSI to the threshold;

determining a percentage of measured RSSIs that exceed the threshold; and

comparing the percentage to an RSSI channel percentage threshold.

21. The method recited in claim 19, further comprising:

comparing each measured RSSI to a threshold for each selected channel;

determining a percentage of measured RSSIs that exceed the threshold for each selected channel; and

comparing the percentage to an RSSI channel percentage threshold for each selected channel.

22. The method recited in claim 19, further comprising:

calculating a function of the measured RSSIs to generate an function RSSI value; and

comparing the function RSSI value to a function RSSI threshold.

23. The method recited in claim 22, where in the function is a sum of the measured RSSIs.

24. The method recited in claim 22, wherein the function is a sum of measured RSSIs for each selected channel.

25. The method recited in claim 17, further comprising:

adjusting the threshold; and

comparing each measured RSSI to the adjusted threshold.

26. The method recite in claim 17, further comprising comparing each measured RSSI to a predetermined threshold.

27. A system for identifying an interferer in a radio communication band, said method comprising:

means for selecting a plurality of test channels in accordance with a channel structure of the interferer;

means for selecting a frequency in each selected channel;

means for measuring a power spectral density in a bandwidth where the interferer is expected by measuring an RSSI at the selected frequency in each of the selected channel and calculating a function value dependent upon the measured RSSIs at the selected frequency; and

means for identifying the interferer in accordance with the measured power spectral density.

28. The system recited in claim 27, further comprising

means for comparing the shape of the measured power spectral density with shapes of power spectral densities for known interferers;

and

means for determining if there is a match in shape.

29. The system recited in claim 27, further comprising means for measuring the power spectral density by estimating the power spectral density using a plurality of narrowband RSSI measurements.

30. The system recited in claim 29, further comprising means for randomizing the RSSI measurements.

31. The system recited in claim 29, further comprising means for varying a time of the RSSI measurements.

32. The system recited in claim 27, further comprising:

means for measuring an RSSI associated with the selected frequency in each selected channel;

means for comparing each measured RSSI to a threshold; and

means for identifying the interfere in accordance with the measured RSSI.