System and method for classifying signals occuring in a frequency band

• US 20030224741A1
• Filed: 04/22/2003
• Published: 12/04/2003
• Est. Priority Date: 04/22/2002
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cognio, Inc. (Cisco Systems, Inc.)
• Inventors: Sugar, Gary L., Diener, Neil R., Miller, Karl A.
• Granted Patent: US 7,116,943 B2
• Time in Patent Office: Days
• US Class Current: 455/115.1
• CPC Class Codes: H04L 1/1664 the supervisory signal being transmitted together with payload signals; piggybacking
• CPC Class Codes: H04W 16/14 Spectrum sharing arrangements between different networks

Abstract

A system and method for classifying signals occurring in a frequency band. One or more characteristics of one or more signals in the frequency band are detected using any suitable technology, such as a device that can generate characteristics of signal pulses detected in the frequency band. Data pertaining to the signal pulses is accumulated over time. The accumulated signal data is compared against reference data associated with known signals to classify the one or more signals in the frequency band based on the comparison. The accumulated data may include one or more characteristics selected from the group consisting of: pulse center frequency, pulse bandwidth, pulse duration, time between pulses and number of different active pulses, and wherein the reference data associated with each of a plurality of known signals comprises one or more characteristics selected from the group consisting of: pulse center frequency, pulse bandwidth, pulse duration and time between pulses. The accumulated signal data is compared against the reference data, and depending on the degree of match with reference data, a signal can be classified. Additional levels of signal classification processing may be performed.

Claims

1. A method for classifying signals occurring in a frequency band, comprising:

a. accumulating data pertaining to one or more characteristics of radio frequency energy received in the frequency band over time;

b. comparing the accumulated data against reference data associated with known signals; and

c. classifying one or more signals occurring the frequency band based on the step of comparing.

2. The method of claim 1, and further comprising the step of detecting one or more characteristics of radio frequency energy received in the frequency band.

3. The method of claim 2, wherein the step of detecting comprises detecting power spectral information of the radio frequency energy.

4. The method of claim 3, wherein the step of accumulating comprises accumulating data pertaining to power spectral information of the radio frequency energy over time.

5. The method of claim 3, wherein the step of detecting comprises detecting signal pulses of radio frequency energy in the frequency band from the power spectral information.

6. The method of claim 5, wherein the step of accumulating data comprises accumulating signal pulse data pertaining to detection of the signal pulses over time.

7. The method of claim 6, wherein the step of accumulating signal pulse data comprises accumulating data for one or more characteristics selected from the group consisting of:

pulse center frequency, pulse bandwidth, pulse duration, time between pulses and number of different active pulses, and wherein the reference data associated with each of a plurality of known signals comprises one or more characteristics selected from the group consisting of;

pulse center frequency, pulse bandwidth and pulse duration.

8. The method of claim 6, wherein the step of comparing comprises comparing accumulated signal pulse data against reference signal pulse data associated with known signal types.

9. The method of claim 1, wherein the step of comparing comprises determining a degree of match between the accumulated data with the reference data.

10. The method of claim 1, and further comprising assigning for the reference data for each known signal, match criteria between characteristics of the reference data and corresponding characteristics in the accumulated data that must be met in order to declare a match between the accumulated data and the reference data.

11. The method of claim 1, wherein the step of classifying comprises determining a signal type of one or more signals occurring in the frequency band.

12. The method of claim 11, and further comprising the step of generating information describing a signal type for one or more signals occurring in the frequency band.

13. The method of claim 11, wherein the step of classifying comprises determining a signal type for one or more signals occurring in the frequency band selected from the group of signal types consisting of:

frequency hopping signal, radar, microwave oven, constant frequency, Bluetooth™

signal, cordless phone, infant monitor transmitter, and video monitor transmitter.

14. The method of claim 7, wherein the step of accumulating data comprises accumulating one or more histograms for the signal pulse, the one or more histograms are selected from the group consisting of:

a center frequency histogram that tracks a percentage of time a given center frequency was observed for detected signal pulses, a bandwidth histogram that tracks the percentage of time a given bandwidth was observed for detected signal pulses, a pulse duration histogram that tracks a percentage of time a given duration or durations was observed for detected signal pulses, a time between pulses histogram that tracks a percentage of time that a given time duration or durations was observed between signal pulses and a number of active transmissions histogram that tracks when several different signal pulses simultaneously occur.

15. The method of claim 5, wherein the step of comparing comprises comparing timing characteristics associated with accumulated signal pulse data with pulse timing characteristics associated with a known signal.

16. The method of claim 15, wherein the step of comparing comprises comparing a time period between two or more signal pulses in the accumulated signal data with a corresponding time period for a known signal.

17. The method of claim 16, wherein the step of comparing comprises comparing a time period between a leading edge of a first signal pulse and a leading edge of a subsequent signal pulse in the accumulated signal data with a corresponding time period for a known signal.

18. The method of claim 1, and further comprising the step of obtaining a sample of a signal detected for a time interval, wherein the step of comparing comprises comparing the sample of the signal with corresponding data for known signals.

19. The method of claim 3, wherein the step of detecting comprises iterating through a plurality of different characteristics for time intervals to detect signal pulses in the frequency band that meet one or more of the plurality of different characteristics.

20. The method of claim 1, and further comprising outputting information including one or more of:

a center frequency of the signal, if relevant, a measure of match confidence, power of the signal and duty cycle of the signal.

21. The method of claim 1, and further comprising displaying one more characteristics of a signal classified from the accumulated data.

22. The method of claim 1, and further comprising steps of receiving a request from an application program interface to classify one or more signal types occurring in the frequency band;

and supplying in response to the request information describing one or more signal types when they are determined to occur.

23. The method of claim 22, wherein the step of receiving a request comprises receiving characteristics of one or more signal types to be analyzed for occurrence in the radio frequency band.

24. A system for classifying signals occurring in a frequency band, comprising:

a. at least one spectrum sensor device that receives radio frequency energy in the radio frequency band and outputs data pertaining to one or more characteristics of radio frequency energy; and

b. a processor that accumulates the data output by the spectrum sensor device and compares the accumulated data against reference data to classify the one or more signals in the frequency band.

25. The system of claim 24, wherein the spectrum sensor device generates power spectral information of the received radio frequency energy.

26. The system of claim 24, wherein the spectrum sensor device comprises a signal detector that detects signal pulses of radio frequency energy in the frequency band from the power spectral information.

27. The system of claim 26, wherein the processor accumulates signal pulse data comprising data associated with signal pulses detected in the frequency band, and wherein the processor compares the accumulated signal pulse data with the reference data comprising signal pulse data associated with known signals.

28. The system of claim 27, wherein the processor accumulates signal pulse data comprising one or more characteristics selected from the group consisting of:

pulse center frequency, pulse bandwidth, pulse duration histogram and time between pulses, and compares the accumulated signal pulse data with reference data comprising one or more characteristics selected from the group consisting of;

pulse center frequency, pulse bandwidth, pulse duration and time between pulses.

29. The system of claim 28, wherein the processor builds one or more histograms for the accumulated signal pulse data.

30. The system of claim 29, wherein the processor builds histograms selected from the group consisting of:

a center frequency histogram that tracks a percentage of time a given center frequency was observed for detected signal pulses, a bandwidth histogram that tracks the percentage of time a given bandwidth was observed for detected signal pulses, a pulse duration histogram that tracks a percentage of time a given duration or durations was observed for detected signal pulses, a time between pulses histogram that tracks percentage of time that a given time duration or durations was observed between signal pulses and a number of active transmissions histogram that tracks when several different signal pulses simultaneously occur.

31. The system of claim 27, wherein the processor compares the accumulated signal data against reference data by comparing a pulse timing signature of a known signal against the accumulated signal data.

32. The system of claim 31, wherein the processor compares timing characteristics associated with accumulated signal pulse data with pulse timing characteristics associated with known signals.

33. The system of claim 31, wherein the processor compares a time period between a leading edge of a first signal pulse and a leading edge of a subsequent signal pulse in the accumulated signal data with a corresponding time period for a known signal.

34. The system of claim 24, wherein the processor compares a sample of a signal detected for a time interval with corresponding data for known signals

35. The system of claim 26, wherein the spectrum sensor device comprises one or more pulse detectors that detect characteristics of signals in the frequency band, and wherein the processor iteratively changes one or more parameters of the one or more pulse detectors to detect signal pulses of different characteristics.

36. The system of claim 24, wherein the spectrum sensor device resides in a card device, and wherein the processor is part of a host device coupled to the card device through an interface.

37. The system of claim 24, wherein the processor outputs information describing a signal type of one or more signals occurring in the frequency band.

38. The system of claim 37, wherein the processor outputs information describing a signal type selected from the group of signal types consisting of:

frequency hopping signal, radar, microwave oven, constant frequency, Bluetooth™

signal, cordless phone, infant monitor transmitter, and video monitor transmitter.

39. The system of claim 37, wherein the processor outputs information for a signal that is classified including one or more of:

a center frequency of the signal, if relevant, a measure of match confidence, power of the signal and duty cycle of the signal.

40. The system of claim 24, wherein the processor generates data to display one or more characteristics of a signal classified from the accumulated data.

41. The system of claim 24, wherein the processor receives a request from an application program interface to classify one or more signal types occurring in the frequency band;

and supplies in response to the request information describing one or more signal types when they are determined to occur.

43. A processor readable medium encoded with instructions that, when executed by a processor, cause the processor to perform steps of:

a. comparing data associated with one or more characteristics of radio frequency energy received in a frequency band against reference data associated with known signals; and

b. classifying one or more signals in the frequency band based on the comparison.

42. The system of claim 44, wherein the processor receives characteristics of one or more signal types to be analyzed for occurrence in the radio frequency band.

44. The processor readable medium of claim 43, wherein the instructions encoded on the medium to perform the comparing step comprise instructions for comparing data associated with signal pulses detected in the frequency band against reference signal pulse data associated with known signal types.

45. The processor readable medium of claim 44, wherein the instructions encoded on the medium to perform the comparing step comprise instructions for comparing one or more characteristics selected from the group consisting of:

pulse center frequency, pulse bandwidth, pulse duration, time between pulses and number of different active transmissions, with reference data associated with each of a plurality of known signal types comprising one or more characteristics selected from the group consisting of;

pulse center frequency, pulse bandwidth, and pulse duration and time between pulses.

46. The processor readable medium of claim 44, wherein the instructions encoded on the medium to perform the comparing step comprise instructions for comparing histograms for the one or more signal pulse characteristics associated with the radio frequency energy with histograms for corresponding one or more characteristics of reference data associated with known signal types.

47. The processor readable medium of claim 43, wherein the instructions encoded on the medium for comparing comprise instructions for comparing timing characteristics associated with accumulated signal pulse data with pulse timing characteristics associated with a known signal.

48. The processor readable medium of claim 47, wherein the instructions encoded on the medium for comparing comprise instructions for comparing a time period between two or more signal pulses in the accumulated signal data with a corresponding time period for a known signal.

49. The processor readable medium of claim 48, wherein the instructions encoded on the medium for comparing comprise instructions for comparing a time period between a leading edge of a first signal pulse and a leading edge of a subsequent signal pulse in the accumulated signal data with a corresponding time period for a known signal.

50. The processor readable medium of claim 46, and further comprising instructions encoded on the medium for outputting information describing a signal type for a classified signal.

51. The processor readable medium of claim 50, and further comprising instructions encoded on the medium for outputting information including one or more of:

a center frequency of the signal, if relevant, a measure of match confidence, power of the signal and duty cycle of the signal.

52. The processor readable medium of claim 50, wherein the instructions encoded on the medium for outputting a signal type comprise instructions for outputting a signal type selected from the group of signal types consisting of:

frequency hopping signal, radar, microwave oven, constant frequency, Bluetooth™

signal, cordless phone, infant monitor transmitter, and video monitor transmitter.

53. The processor readable medium of claim 43, and further comprising instructions encoded on the medium to generate data for displaying information describing the classified signal.

54. The processor readable medium of claim 43, and further comprising instructions encoded on the medium for receiving a request from an application program interface to classify one or more signal types occurring in the frequency band;

and supplying in response to the request information describing one or more signal types when they are determined to occur.

55. The processor readable medium of claim 54, wherein the instructions encoded on the medium for receiving a request further comprise instructions for receiving characteristics of one or more signal types to be analyzed for occurrence in the radio frequency band.

56. A software system that processes data representing activity in a radio frequency band where signals of multiple types may occur, comprising:

a. a first process for accumulating data associated with activity in the radio frequency band; and

b. a second process that classifies types of signals occurring in the radio frequency band based on data from the first process.

57. A device that receives radio frequency energy in a radio frequency band and processes signals representative thereof, comprising:

a. a radio receiver that receives radio frequency energy in a radio frequency band where signals of multiple types may be occurring;

b. a spectrum analyzer that computes power values for radio frequency energy received in at least part of the radio frequency band for a time interval;

c. a signal detector coupled to the spectrum analyzer that detects signal pulses of radio frequency energy that meet one or more characteristics; and

d. a processor coupled to receive output of the spectrum analyzer and the signal detector, wherein the processor is programmed to;

i. accumulate data pertaining to signal pulses detected by the signal detector; and

ii. compare accumulated data against reference data associated with known signals to classify one or more signals occurring in the frequency band.

58. The device of claim 57, wherein the processor accumulates for each signal pulse detected by the signal detector one or more of:

pulse center frequency, pulse bandwidth, pulse duration, time between pulses and number of different active pulses.

59. The device of claim 58, wherein the processor generates controls for configuring signal pulse characteristics used by the signal detector to detect signal pulses from the radio frequency energy.