Methods for detecting and classifying signals transmitted over a radio frequency spectrum
A method for classifying a signal is disclosed. The method can be used by a station or stations within a network to classify the signal as non-cooperative (NC) or a target signal. The method performs classification over channels within a frequency spectrum. The percentage of power above a first threshold is computed for a channel. Based on the percentage, a signal is classified as a narrowband signal. If the percentage indicates the absence of a narrowband signal, then a lower second threshold is applied to confirm the absence according to the percentage of power above the second threshold. The signal is classified as a narrowband signal or pre-classified as a wideband signal based on the percentage. Pre-classified wideband signals are classified as a wideband NC signal or target signal using spectrum masks.
1. A method for classifying a signal within a channel, the method comprising:
receiving a radio frequency signal at a signal classifier;
determining whether the signal is a narrowband signal by comparing a first threshold and a second threshold to the received signal, and determining a percentage of the spectrum occupied by the signal above the second threshold, wherein the second threshold is lower than the first threshold;
comparing a mask to the spectrum within the channel to determine a degree of correlation between the mask and the received signal;
if the degree of correlation between the mask and the received signal is above a correlation threshold, classifying the received signal as a target signal; and
if the received signal is not determined to be a narrowband signal or a target signal, classifying the signal as a wideband signal.
2. The method of claim 1 , further comprising classifying the signal as no signal by comparing a third threshold and a fourth threshold to the received signal.
3. The method of claim 1 , further comprising looping to another channel from the channel.
4. The method of claim 1 , further comprising determining a type of the received signal according to the mask.
5. The method of claim 1 , wherein the step of determining the signal is a narrowband signal comprises applying a channel mask to the channel to determine the narrowband signal.
6. The method of claim 1 , further comprising computing a power spectrum envelope within the channel.
7. The method of claim 4 , wherein the target signal is determined to be a cooperative signal.
8. The method of claim 4 , wherein the target signal is determined to be a cognitive radio signal.
9. The method of claim 4 , wherein the target signal is determined to be a next generation (XG) radio signal.
10. The method of claim 1 , wherein the mask is selected from a defined set of masks.
11. A method for detecting a target signal, the method comprising:
receiving a radio frequency signal at a signal classifier;
determining that the received signal is not a narrowband signal by comparing a first threshold and a second threshold to the received signal and determining a percentage of the spectrum occupied by the signal above the second threshold;
determining that the received signal is not a wideband signal;
subsequent to determining that the received signal is not a wideband signal and that the received signal is not a narrowband signal, applying a channel mask to determine a degree of correlation between the mask and the received signal; and
based upon the degree of correlation between the mask and the received signal, determining that the signal is a target signal.
12. The method of claim 11 , further comprising classifying the target signal according to the channel mask.
13. The method of claim 11 , further comprising looping through a plurality of channel masks to select the channel mask.
14. The method of claim 11 , further comprising classifying the received signal as a cooperative signal.
15. The method of claim 11 , further comprising classifying the received signal as a cognitive radio signal.
16. The method of claim 11 , further comprising classifying the received signal as a next generation (XG) radio signal.
17. A system comprising:
a receiver configured to receive a radio frequency signal;
a signal classifier in communication with the receiver, the signal classifier configured to:
compare a first threshold and a second threshold to the received signal to determine whether the received signal is a narrowband signal, and determine a percentage of the spectrum occupied by the signal above the second threshold, wherein the second threshold is lower than the first threshold;
compare a mask to the spectrum within a channel to determine a degree of correlation between the mask and the received signal;
classify the received signal as a signal if the degree of correlation between the mask and the received signal is above a correlation threshold; and
classify the received signal as a wideband signal if the received signal is not determined to be a narrowband signal or a target signal.
18. The system of claim 17 , wherein the signal classifier is further configured to classify the signal as no signal by comparing a third threshold and a fourth threshold to the received signal.
19. The system of claim 17 , wherein the receiver is further configured to loop to another channel from the channel.
20. The system of claim 17 , wherein the step of determining whether the signal is a target signal further comprises determining a type of the target signal according to the mask.
21. The system of claim 17 , wherein the mask is selected from a defined set of masks.
22. The system of claim 17 , wherein the signal classifier is further configured to determine the target signal to be at least one of a cooperative signal, a cognitive radio signal, or a next generation (XG) radio signal.
23. The system of claim 17 , wherein the receiver and the signal classifier are disposed within the same physical radio.