Patent ID: 9379924
Filing Date: 2016-06-28
CPC Classification: H04L

Claim Text:
1. A method for spectrum sensing for cognitive radio, the method comprising: detecting edges of frequency bands, detecting energies in frequency bands, and to decide whether frequency bands are available to cognitive radio users; receiving a time-domain signal by a cognitive radio user; estimating a power spectral density of the time-domain signal; calculating wavelet transform coefficients at one or more scale factors by convolving the power spectral density with a first derivative of a wavelet smoothing function; obtaining a positive signal by taking the absolute value of all wavelet transform coefficients, and in response to more than one wavelet scale factor being used, combining wavelet transform coefficients of different scales; comparing the positive signal to a noise threshold and where the positive signal is less than the noise threshold setting the positive signal to zero; detecting one or more frequency-band edges of the power spectral density by solving for peak frequencies, wherein the peak frequencies are frequencies of the local maxima of the positive signal; defining a plurality of frequency bands as all frequencies between nearest neighbor pairs of frequency-band edges; determining a received energy value for a first frequency band of a plurality of frequency bands comparing the received energy value to an energy threshold; and signaling frequency band availability based on the comparison between the received energy value and the energy threshold.