System and method for identifying interferes in a communication spectrum

• US 20040132410A1
• Filed: 01/08/2003
• Published: 07/08/2004
• 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.
• Granted Patent: US 7,133,686 B2
• Time in Patent Office: Days
• US Class Current: 455/67.13
• 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 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 an RSSI associated with the selected frequency in each selected channel; and

identifying the interferer in accordance with the measured RSSIs.

2. The method recited in claim 1, further comprising comparing each measured RSSI to a threshold.

3. The method recited in claim 2, further comprising:

determining a percentage of measured RSSIs that exceed the threshold;

comparing the percentage to an RSSI channel percentage threshold.

4. The method recited in claim 1, further comprising:

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

measuring an RSSI corresponding to each additional selected frequency.

5. The method recited in claim 4, 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.

6. The method recited in claim 4, 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.

7. The method recited in claim 4, 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.

8. The method recited in claim 7, where in the function is a sum of the measured RSSIs.

9. The method recited in claim 7, wherein the function is a sum of measured RSSIs for each selected channel.

10. The method recited in claim 1, further comprising:

adjusting the threshold; and

comparing each measured RSSI to the adjusted threshold.

11. The method recite in claim 1, further comprising comparing each measured RSSI to a predetermined threshold.

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

means for identifying the interferer in accordance with the measured RSSIs.

13. The system recited in claim 12, further comprising means for comparing each measured RSSI to a threshold.

14. The system recited in claim 13, further comprising:

means for determining a percentage of measured RSSIs that exceed the threshold;

means for comparing the percentage to an RSSI channel percentage threshold.

15. The system recited in claim 12, further comprising:

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

means for measuring an RSSI corresponding to each additional selected frequency.

16. The system recited in claim 15, further comprising:

means for comparing each measured RSSI to the threshold;

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

means for comparing the percentage to an RSSI channel percentage threshold.

17. The system recited in claim 15, wherein the:

means for comparing each measured RSSI to the threshold for each selected channel;

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

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

18. The system recited in claim 15, further comprising:

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

means for comparing the function RSSI value to a function RSSI threshold.

19. The system recited in claim 16, where in the function is a sum of the measured RSSIs.

20. The system recited in claim 16, wherein the function is a sum of measured RSSIs for each selected channel.

21. The system recited in claim 12, further comprising:

means for adjusting the threshold; and

means for comparing each measured RSSI to the adjusted threshold.

22. The system recite in claim 12, further comprising means for comparing each measured RSSI to a predetermined threshold.

23. A cordless telephone system for identifying an interferer comprising:

a handset;

a base unit in communication with the handset;

a receiver to receive a signal centered at a frequency, the frequency selected in accordance with known characteristics about the interferer;

a microprocessor configured to measure an RSSI corresponding to the frequency, to compare the measured RSSI to an RSSI threshold and to indicate that the interferer is present when the measured RSSI exceeds the predetermined RSSI.

24. The cordless telephone system recited in claim 23, wherein the receiver is located in the handset.

25. The cordless telephone system recited in claim 23, wherein the receiver is located in the base unit.

26. The cordless telephone system recited in claim 23, wherein the microprocessor commands the receiver to tune to a plurality of frequencies, and wherein the microprocessor determines an RSSI at each frequency of the plurality of frequencies, compares the measured RSSI to the RSSI threshold, determines a percentage of RSSIs that exceed the RSSI threshold and indicates that the interferer is present if the determined percentage exceeds an RSSI channel threshold.

27. The cordless telephone system recited in claim 23, wherein the microprocessor is located in the handset.

28. The cordless telephone system recited in claim 23, wherein the microprocessor is located in the base unit.

29. The cordless telephone system recited in claim 23, wherein the RSSI threshold is predetermined.

30. The cordless telephone system recited in claim 23, wherein the RSSI threshold is dynamically adjustable.

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

selecting N channels based on known;

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

measuring an RSSI at each of the selected frequencies within each of the selected N channels;

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.

32. The method recited in claim 31, further comprising randomizing measuring the RSSIs.

33. The method recited in claim 32, further comprising selecting frequencies for measuring RSSI independent of previous measurements.

34. The method recited in claim 32, further comprising measuring RSSI for all frequencies in one channel prior to measuring RSSI for any frequency in another channel.

35. The method recited in claim 32, further comprising measuring RSSI for any frequency in any channel regardless of whether RSSI has been measured for all frequencies in a particular channel.

36. The method recited in claim 31, further comprising measuring RSSIs substantially simultaneously.

37. The method recited in claim 31, further comprising not measuring RSSIs substantially simultaneously.

38. The method recited in claim 31, wherein the threshold is predetermined.

39. The method recited in claim 31, wherein the threshold is dynamically adjustable.

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

a handset, the 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 microprocessor to measure an RSSI at the particular frequency, compare the RSSI to a threshold and identify the interferer if the RSSI exceeds the threshold; and

a base unit in communication with the handset.

41. The cordless telephone system recited in claim 40, 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 interferer;

a signal conditioning unit to process and digitize the signal;

a memory to store the digitized signal; and

a microprocessor 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.

42. The cordless telephone system recited in claim 40, wherein the threshold is predetermined.

43. The cordless telephone system recited in claim 40, wherein the threshold is dynamically adjustable.

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

a handset; and

a base unit in communication with the handset, the base unit 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; and

a receiver to measure an RSSI at the particular frequency; and

a processor to compare the RSSI to a threshold and identify the interferer if the RSSI exceeds the threshold.

45. The cordless telephone system recited in claim 44, wherein the threshold is predetermined.

46. The cordless telephone system recited in claim 44, wherein the threshold is dynamically adjustable.

47. 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;

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

48. The method recited in claim 47, further comprising

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

and

determining if there is a match in shape.

49. The method recited in claim 47, further comprising measuring the power spectral density by estimating the power spectral density using a plurality of narrowband RSSI measurements.

50. The method recited in claim 49, further comprising randomizing the RSSI measurements.

51. The method recited in claim 49, further comprising varying a time of the RSSI measurements.