System and method for signal classiciation of signals in a frequency band

• US 6,850,735 B2
• Filed: 09/18/2002
• Issued: 02/01/2005
• 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.
• Primary Examiner(s): Nguyen, Simon
• Application Number:
  US10/246,364
• Publication Number:
  US 20040203826A1
• Time in Patent Office: 867 Days
• Field of Search: 455/67.11, 455/115.1, 455/115.2, 455/115.3, 455/115.4, 455/176.1, 455/179.1, 455/180.1, 455/226.1, 375/224, 375/340
• US Class Current: 455/67.11
• CPC Class Codes: H04B 17/309 Measuring or estimating channel quality parameters
• 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. detecting signal pulses associated with one or more signals in the frequency band;

b. accumulating signal pulse data pertaining to detection of the signal pulses over time, the signal pulse data comprising one or more of;

pulse center frequency, pulse bandwidth, pulse duration, time between pulses and number of different signal pulses detected; and

c. analyzing the signal pulse data with respect to data associated with known signals to classify the one or more signals occurring in the frequency band.

2. The method of claim 1, wherein the step of detecting comprises detecting signal pulses associated with the one or more signals in the frequency band.

3. The method of claim 1, wherein the step of analyzing comprises analyzing the signal pulse data against definition data that includes signal descriptive information associated with known signal pulses.

4. The method of claim 3, wherein the step of analyzing comprises determining a degree of match between one or more characteristics of the signal pulse data with the data associated with known signals.

5. The method of claim 3, and further comprising assigning for a known signal, match criteria between characteristics of the data associated with a known signal and corresponding characteristics in the accumulated signal pulse data that must be met in order to declare a match.

6. The method of claim 3, wherein the step of analyzing comprises analyzing the signal pulse data against definition data, wherein the definition data comprises one or more of:

(1) characteristics of signal pulse data including one or more of center frequency, pulse duration, bandwidth and time between pulses;

(2) definition of recurring pulse patterns common to a particular communication protocol or standard;

(3) iterative test definitions that search for specific signal pulse data characteristics;

(4) algorithms that examine statistics and pulse types for a specific device; and

(5) algorithms that process historical statistics derived from the signal pulse data over relatively longer periods of time.

7. The method of claim 3, wherein the steps of detecting, accumulating and analyzing are performed in a first device, and further comprising the step of receiving definition data from a second device for use by the first device in performing the step of classifying.

8. The method of claim 1, wherein the step of accumulating data comprises accumulating histograms for the one or more characteristics.

9. The method of claim 8, wherein the step of accumulating data comprises accumulating one or more histograms including:

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 detected signal pulses and a number of active transmissions histogram that tracks a percentage of time that a given number of signal transmissions was observed.

10. The method of claim 1, and further comprising the step of obtaining raw samples of received energy for a time interval, wherein the step of analyzing further comprises analyzing the raw samples.

11. The method of claim 10, wherein the step of classifying comprises analyzing the raw samples to determine if they sufficiently match a synchronization portion of a known communication signal.

12. The method of claim 1, wherein the step of detecting comprises iterating through a plurality of different signal pulse characteristics for time intervals to detect signals in the frequency band that meet one or more of the plurality of different signal pulse characteristics.

13. The method of claim 1, wherein the step of classifying further comprises outputting, for a signal that can be classified, information that describes the type of signal, as well as one or more of:

a center frequency of the signal, if relevant, a measure of probability that there is a match, power of the signal and duty cycle of the signal.

14. The method of claim 1, wherein the step of analyzing comprises analyzing the signal pulse data with data describing patterns associated with known signals.

15. The method of claim 14, wherein the step of analyzing comprises analyzing the signal pulse data for recurring signal pulse patterns.

16. The method of claim 15, wherein the step of analyzing comprises analyzing the signal pulse data for a time period between successive signal pulses.

17. The method of claim 1, wherein the step of detecting comprises detecting, from data representing received energy in the frequency band, signal pulses that fall within a range of one or more of:

bandwidth, duration, and center frequency.

18. The method of claim 17, wherein the step of accumulating comprises accumulating pulse event data associated with signal pulses occurring in the frequency band that are determined to fall within a range of one or more of:

bandwidth, duration, and center frequency.

19. The method of claim 18, wherein the step of detecting comprises detecting, from the data representing received energy in the frequency band, multiple types of signal pulses that may be simultaneously occurring in the frequency band and that fall within a corresponding range of one or more of:

bandwidth, duration, and center frequency.

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

a. a memory that stores accumulated signal pulse data comprising one or more of;

pulse center frequency, pulse bandwidth, pulse duration and time between pulses for signal pulses detected in the frequency band over time; and

b. a processor coupled to the memory that analyzes the accumulated signal pulse data with respect to data associated with known signals to classify one or more signals occurring in the frequency band.

21. The system of claim 20, wherein the processor analyzes the accumulated signal pulse data with respect to definition data that includes signal descriptive information associated with known signals.

22. The method of claim 21, wherein the processor analyzes the signal pulse data against definition data, wherein the definition data comprises one or more of:

(1) characteristics of signal pulse data including one or more of center frequency, pulse duration, bandwidth and time between pulses;

(2) definition of recurring pulse patterns common to a particular communication protocol or standard;

(3) iterative test definitions that search for specific signal pulse data characteristics;

(4) algorithms that examine statistics and pulse types for a specific device; and

(5) algorithms that process historical statistics derived from the signal pulse data over relatively longer periods of time.

23. The system of claim 20, wherein the memory stores accumulated data comprising histograms for the one or more characteristics.

24. The system of claim 23, wherein the memory stores accumulated data comprising histograms selected from the group consisting of:

a center frequency histogram that tracks a percentage of time a given center frequency was observed for a signal pulse, a bandwidth histogram that tracks the percentage of time a given bandwidth was observed for a signal pulse, a pulse duration histogram that tracks a percentage of time a given duration was observed for a signal pulse, 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 a percentage of time that a given number of different signal transmissions was observed.

25. The system of claim 20, wherein the processor further analyzes raw samples of received energy for a time interval.

26. The system of claim 25, wherein the processor analyzes the raw samples to determine if they sufficiently match a synchronization portion of a known communication signal.

27. The system of claim 20, and further comprising one or more pulse detector circuits that detect signal pulses having characteristics that fall within a range of one or more of:

bandwidth, center frequency band and duration.

28. The system of claim 27, wherein the processor changes parameters of the one or more pulse detector circuits to detect signals pulses of different characteristics.

29. The system of claim 27, and comprising a plurality of pulse detector circuits each of which detects signal pulses that have characteristics that fall within a corresponding range of one or more of:

bandwidth, center frequency band and duration, so as to detect multiple types of signal pulses that may be simultaneously occurring in the frequency band.

30. The system of claim 20, wherein the memory resides in a first device and the processor resides in a second device, and wherein the first device transmits the accumulated signal pulse data to the second device for processing by the processor.

31. The system of claim 20, and further comprising a spectrum analysis device that generates signal pulse data pertaining to signals occurring in the frequency band and outputs the signal pulse data to the memory.

32. The system of claim 31, and further comprising a radio receiver that receives signals occurring in the frequency band and outputs baseband signals representative thereof to the spectrum analysis device.

33. The system of claim 32, wherein the spectrum analysis device and the radio receiver are implemented in a card device, and wherein the processor is included in a host device coupled to the card device.

34. The system of claim 20, wherein the processor generates as output for a signal that can be classified, information that describes the type of signal, as well as one or more of:

a center frequency of the signal, if relevant, a measure of probability that there is a signal match, power of the signal and duty cycle of the signal.

35. The system of claim 20, wherein the processor compares the signal pulse data with data describing a time period between successive signal pulses associated with a known signal.

47. The medium of claim 35, and further comprising instructions encoded on the medium that cause the processor to generate the signal pulse data.

48. The medium of claim 47, wherein the instructions encoded on the medium for performing the step of detecting comprises instructions for detecting from data representing received energy in the frequency band, multiple types of signal pulses that may be simultaneously occurring in the frequency band and that fall within a corresponding range of one or more of:

bandwidth, duration, and center frequency.

36. A method for generating data indicative of a signal of a device operating in a frequency band, comprising steps of:

a. detecting signal pulses associated with signals transmitted by the device operating in the frequency band;

b. accumulating signal pulse data pertaining to the detected signal pulses over time, the signal pulse data comprising one or more of;

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

c. generating from the accumulated signal pulse data signal classification definition data useful to classify or identify the device when it operates in the frequency band.

37. The method of claim 36, wherein the step of accumulating data comprises accumulating one or more histograms selected from the group consisting of:

a center frequency histogram that tracks a percentage of time a given center frequency was observed for a signal pulse, a bandwidth histogram that tracks the percentage of time a given bandwidth was observed for a signal pulse, a pulse duration histogram that tracks a percentage of time a given duration was observed for a signal pulse, 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 a percentage of time that a given number of different signal transmissions was observed.

38. The method of claim 36, and further comprising the step of defining match criteria between the definition data and signal pulse data of a detected signal in order to declare that the detected signal is a match.

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

a. accumulating signal pulse data pertaining to detection of signal pulses associated with one or more signals occurring in a frequency band, the signal pulse data comprising one or more of;

signal pulse center frequency, signal pulse bandwidth, signal pulse duration, time between signal pulses and number of different signal pulses detected in the frequency band; and

b. classifying the one or more signals in the frequency band by analyzing the signal pulse data with respect to data associated with known signals.

40. The medium of claim 39, wherein the instructions encoded on the medium to perform the classifying step comprise instructions for analyzing the accumulated signal pulse data with respect to definition data that includes signal descriptive information associated with known signals derived from one or more of:

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

41. The medium of claim 40, wherein the instructions encoded on the medium to perform the classifying step comprise instructions for analyzing the signal pulse data against definition data, wherein the definition data comprises one or more of:

(1) characteristics of signal pulse data including one or more of center frequency, pulse duration, bandwidth and time between pulses;

(2) definition of recurring pulse patterns common to a particular communication protocol or standard;

(3) iterative test definitions that search for specific signal pulse data characteristics;

(4) algorithms that examine statistics and pulse types for a specific device; and

(5) algorithms that process historical statistics derived from the signal pulse data over relatively longer periods of time.

42. The medium of claim 39, wherein the instructions encoded on the medium to perform the classifying step comprise instructions for determining a degree of match between one or more characteristics of the signal pulse data with the data associated with known signals.

43. The memory medium of claim 42, and further comprising instructions encoded on the medium for assigning match criteria between characteristics of the data associated with known signals and signal pulse data that must be met in order to declare a match.

44. The medium of claim 39, and further comprising instructions encoded on the medium for analyzing raw samples of received energy for a time interval in order to classify the signal.

45. The medium of claim 44, and further comprising instructions encoded on the medium for analyzing the raw samples to determine if they sufficiently match a synchronization portion of a known communication signal.

46. The memory medium of claim 39, and further comprising instructions encoded on the medium for outputting, for a signal that can be classified, information that describes the type of signal, as well as one or more of:

a center frequency of the signal, if relevant, a measure of probability that the signal matches the identifier, power of the signal and duty cycle of the signal.

49. The medium of claim 39, wherein the instructions encoded on the medium for performing the step of comparing comprise instructions for comparing the signal pulse data with data describing a time period between successive signal pulses associated with a known signal.

50. The medium of claim 39, wherein the instructions encoded on the medium for performing the step of accumulating comprise instructions for accumulating pulse event data associated with signal pulses occurring in the frequency band that are determined to fall within a range of one or more of:

bandwidth, duration, and center frequency.

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

a. a radio receiver that receives signals occurring in the frequency band and outputs signals representative thereof;

b. a spectrum analysis device that generates signal pulse data pertaining to signals occurring in the frequency band based on the signals output by the radio receiver;

c. a memory that stores accumulated signal pulse data pertaining to signals occurring in the frequency band over time that is output by the spectrum analysis device; and

d. a processor coupled to the memory that analyzes the accumulated signal pulse data to classify one or more signals occurring in the frequency band;

e. wherein the spectrum analysis device and the radio receiver are implemented in a card device, and wherein the processor is included in a host device coupled to the card device.

52. The system of claim 51, wherein the spectrum analysis device detects, from signals output of the radio receiver, signal pulses that fall within a range of one or more of:

bandwidth, duration, and center frequency, and outputs signal pulse data for signal pulses that fall within such ranges.

53. The system of claim 52, wherein the processor accumulates the signal pulse data, the signal pulse data comprising one or more of:

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

54. The system of claim 53, wherein the processor analyzes the signal pulse data with respect to definition data that includes signal descriptive information associated with known signal pulses.

55. The system of claim 54, wherein the processor analyzes the signal pulse data against definition data, wherein the definition data comprises one or more of:

(1) characteristics of signal pulse data including one or more of center frequency, pulse duration, bandwidth and time between pulses;

(2) definition of recurring pulse patterns common to a particular communication protocol or standard;

(3) iterative test definitions that search for specific signal pulse data characteristics;

(4) algorithms that examine statistics and pulse types for a specific device; and

(5) algorithms that process historical statistics derived from the signal pulse data over relatively longer periods of time.

56. The system of claim 51, wherein the processor further analyzes raw samples of received energy for a time interval.

57. The system of claim 56, wherein the processor analyzes the raw samples to determine if they sufficiently match a synchronization portion of a known communication signal.

58. The system of claim 51, wherein the processor generates as output for a signal that can be classified, information that describes the type of signal, as well as one or more of:

a center frequency of the signal, if relevant, a measure of probability that there is a signal match, power of the signal and duty cycle of the signal.