Method and system for classifying communication signals in a dynamic spectrum access system
Methods and systems for dynamic spectrum access (DSA) in a wireless network are provided. A DSA-enabled device may sense spectrum use in a region and, based on the detected spectrum use, select one or more communication channels for use. The devices also may detect one or more other DSA-enabled devices with which they can form DSA networks. A DSA network may monitor spectrum use by cooperative and non-cooperative devices, to dynamically select one or more channels to use for communication while avoiding or reducing interference with other devices.
1. A method of classifying the status of a channel by a dynamic spectrum access-enabled device, said method comprising:
determining a channelization for a region of spectrum;
measuring energy present in a plurality of channels defined by the channelization;
generating a first confidence score indicating the difference between a predefined signal mask and energy levels measured in a first group of the plurality of channels;
generating a second confidence score indicating the difference between the predefined signal mask and energy levels measured in a second group of the plurality of channels, the second group of channels including at least one channel comprising a higher frequency than each channel in the first group of channels; and
in response to at least one of the first and second confidence scores exceeding a predefined threshold, classifying the corresponding group of channels as containing a cooperative signal.
2. The method of claim 1 , further comprising classifying the corresponding group of channels as containing a dynamic spectrum access signal.
3. The method of claim 1 , the first and second group of channels having at least one channel in common.
4. The method of claim 1 , the first and second group of channels having no channels in common.
5. The method of claim 1 , wherein the frequency range encompassed by the first and second group of channels corresponds to a predefined channelization.
6. The method of claim 1 , wherein the channelization is different than a channelization associated with a non-cooperative signal expected in the region of spectrum.
7. A method of operating a dynamic spectrum access-enabled device, said method comprising:
determining a channelization for a region of spectrum;
measuring energy present in at least one channel defined by the channelization;
based on the measured energy, identifying a signal in the at least one channel;
comparing the detected signal to a predefined signal mask, the signal mask defining a power-frequency relationship for a modeled signal in the at least one channel;
calculating a confidence score based on the comparison of the detected signal to the signal mask, the confidence score indicating the likelihood that the signal is a cooperative signal; and
based on the confidence score, classifying the signal identified in the at least one channel as at least one of a non-cooperative signal, a primary signal, and a cooperative signal.
8. The method of claim 7 , wherein the channelization is different than a channelization associated with a non-cooperative signal expected in the region of spectrum.
9. The method of claim 7 , further comprising the step of communicating with a cooperative device on the at least one channel.
10. The method of claim 7 , further comprising:
identifying a known non-cooperative signal bandwidth corresponding to a region of spectrum that includes the at least one channel; and
selecting the signal mask to have a bandwidth different than the non-cooperative signal bandwidth.
11. The method of claim 7 , further comprising:
identifying the type of signal detected in the at least one channel as being a type expected for a cooperative signal.
12. The method of claim 7 , further comprising:
prior to identifying the signal in the at least one channel, measuring noise occurring in the channel for a period of time; and
reducing the value of the measured energy used to identify the signal in said identifying step based on the noise measured during the period of time.
13. The method of claim 7 , said step of calculating the confidence score further comprising:
calculating the difference in mean values between the signal mask and the detected signal in one or more pass-bands.
14. The method of claim 7 , said step of calculating the confidence score further comprising:
calculating the difference in mean values between the signal mask and the detected signal in one or more stop-bands.
15. The method of claim 7 , said step of calculating the confidence score further comprising:
calculating the difference in the variance between the signal mask and the detected signal in one or more pass-bands.
16. The method of claim 7 , said step of calculating the confidence score further comprising:
calculating the difference in the variance between the signal mask and the detected signal in one or more stop-bands.
17. The method of claim 7 , said step of calculating the confidence score further comprising:
calculating the distance between the amplitude of the center pass-band of the detected signal and the side guard-bands of the detected signal; and
calculating the difference between the calculated distance and the distance between the amplitude of the center pass-band of the signal mask and the side guard-bands of the signal mask.
18. The method of claim 7 , said step of calculating the confidence score further comprising:
calculating the difference between the peak-to-mean ratio of the signal mask and the peak-to-mean ratio of the detected signal.
19. A dynamic spectrum access-enabled device comprising:
a detector configured to measure energy present in at least one channel;
a first circuit to:
identify a signal in the at least one channel based on the energy measured by said detector;
compare the detected signal to a predefined signal mask, the signal mask defining a power-frequency relationship for a modeled signal in the at least one channel;
calculate a confidence score based on the comparison of the detected signal to the signal mask, the confidence score indicating the likelihood that the signal is a cooperative signal; and
based on the calculated confidence score, classify the signal identified in the at least one channels as available for use by the device node.
20. The device of claim 19 , wherein said first circuit comprises a signal classifier.
21. The device of claim 19 , wherein said detector is further configured to measure energy present in at least one of a first side portion and a second side portion of a narrow channel, the first side portion being defined by a first frequency range and the second side portion being defined a second frequency range, the second frequency range being higher than and non-overlapping with the first frequency range.
22. The device of claim 21 , further comprising a second circuit to
define an energy threshold equal to the measured energy level; and
measure energy present in a central portion of the narrow channel, the central portion being defined by a central frequency range between the first and second frequency ranges and, if the energy measured in the central portion is at least as great as the threshold, classify a signal detected in the narrow channel as a cooperative signal.
23. The device of claim 19 , further comprising:
a second circuit to determine the availability of the at least one channel for use by the device based on signal classification data received from the first circuit.
24. The device of claim 23 , further comprising a policy module to specify how often the detector measures energy in the at least one channel.
25. The device of claim 19 , wherein said device is a secondary device in the at least one channel.
26. The device of claim 19 , wherein said device is a base station.
27. A method of identifying a cooperative signal by a dynamic spectrum access-enabled device, said method comprising:
measuring energy present in at least one of a first side portion and a second side portion of a narrow channel, the first side portion being defined by a first frequency range and the second side portion being defined a second frequency range, the second frequency range being higher than and non-overlapping with the first frequency range;
setting an energy threshold to be the value of the energy measured in said side portion measuring step;
measuring energy present in a central portion of the narrow channel, the central portion being defined by a central frequency range between the first and second frequency ranges;
if the energy measured in the central portion is at least as great as the threshold, classifying a signal detected in the narrow channel as a cooperative signal.
28. The method of claim 27 , wherein the narrow channel is defined by a channelization different than a channelization associated with a non-cooperative signal expected in a region of spectrum that includes the narrow channel.
29. The method of claim 27 , further comprising the step of communicating with a cooperative device on the narrow channel.
30. The method of claim 27 , further comprising:
prior to classifying the signal as a cooperative signal, measuring noise occurring in the channel for a period of time; and
reducing the value of the measured energy used to identify the signal in said classifying step based on the noise measured during the period of time.