Cooperative spectrum sensing with censoring of cognitive radios in Rayleigh fading channel

Performance of cooperative spectrum sensing has been assessed in presence of Rayleigh fading. Cognitive radio (CR) users which employ energy detectors are censored depending on the quality of radio channels between them and a fusion center (FC). A training based channel estimator is used at the FC to estimate the complex Gaussian fading coefficients characterizing the channels between the CR users and the FC. This channel state information (CSI) on fading coefficients is used for censoring the CR users. Each CR makes a hard decision about the primary user (PU) using energy detection and transmits the information to the FC using BPSK signaling if the CR user is selected to transmit. Several fusion rules such as OR logic, majority logic, likelihood ratio test (LRT) fusion are applied at the FC for estimating the performance in terms of missed detection probability (P_m). Comparative performance of fusion rules in terms of probability of missed detection has been evaluated under both perfect and imperfect channel estimation for various probabilities of false alarm (P_f), average reporting and sensing channel SNR values.