Abstract: Radio frequency spectrum is a very valuable resource in wireless communication. Its usage is increasing day by day at a tremendous rate. Since the available spectrum is limited, there is a need to find a way, to efficiently utilize this scarce spectrum. Cognitive radio is a huge step towards this. Cognitive radio helps the secondary users to use the unused licensed spectrum and drop out it when primary users are active. Spectrum sensing is a major function of cognitive radio. Commonly used spectrum sensing techniques are energy based spectrum sensing, matched filter spectrum sensing and cyclo stationary based spectrum sensing. In this paper, Energy detection, Cyclostationary detection and Adaptive double Threshold Energy Detection (ED_ADT) schemes were compared under different channels like AWGN, Rayleigh, and Rician. Results show that ED_ADT is optimal for signal detection having low SNR.

Keywords: Adaptive Double Threshold Energy Detector, Cognitive Radio, Cyclostationary Detector, Energy Detector, Probability of Detection.