A Simple Chirping-Based Spectrum Sensing Scheme for Cognitive Radio Applications

Abstract

In this study, we propose a simple spectrum sensing method based on exploiting the properties of a group-delay phaser. Following the theory that an additive white noise should have a flat spectrum over the band of interest, which is not the case for most data-modulated signals, the spectrum shape of input waveforms has been the test variable. The latter enables a clear distinguishing method between a noise background and a communication signal of a transmission body operating over the desired band. The phaser scatters the frequency components of received signals in time space, allowing a time-domain inspection of the corresponding spectral response. The accurate closed-form analytical expression for the probability of detection in an additive white Gaussian noise (AWGN) channel has been derived, in addition to the false alarm probability. The probability of detection has been studied versus signal-to-noise ratio (SNR) in AWGN and multipath channels. As well, the receiver operating characteristic (ROC) curves have been plotted for different values of SNR. A good performance has been achieved by our scheme, which has recorded a detection probability of 0.86 for a false alarm probability of 0.1, and further shown a kind of robustness against noise uncertainties. Experimental works have eventually been conducted, and the empirical results also validate the effectiveness of the elaborated approach. An improvement of around 30% in the probability of detection has been realized over the energy-based sensing technique, at low measures of false alarm probability.