Analytical and experimental performance comparison of energy detectors for cognitive radios

Energy detection has been adopted as an alternative spectrum sensing method for cognitive radios due to its low computational complexity without requiring a priori information of the signal to be detected. In this work, we analyze the accuracy of different energy detector models in approximating the exact solution in AWGN and Rayleigh channels. Our simulations show that all of these models have almost the same performance in Rayleigh channels. Hence, we conclude that any one of them can be used to represent the energy detector's performance instead of the complicated exact solution in Rayleigh fading channels. Using Edell's model, we derive the relationship between the number of samples (N) and the signal-to-noise ratio (SNR) for a single Rayleigh channel similar to the one obtained for AWGN channels. We also introduce a fading factor that relates the SNR in Rayleigh fading channels to AWGN channels by fixing the number of samples. Furthermore, we analyze the effect of multiple antennas for cognitive radios and quantify the improvement in performance regarding this factor. All the analytical results derived in this thesis are verified by simulations and experimental results are also provided.