Censoring-Based Cooperative Spectrum Sensing with Improved Energy Detectors and Multiple Antennas in Fading Channels

In this paper, the performance of cooperative spectrum sensing (CSS) with threshold-based censoring is investigated in the presence of noisy and faded environments. In particular, scenarios with Rayleigh, Hoyt, and Rician fading, affecting both the sensing (S) and reporting (R) channels, are considered. Each secondary user (SU) is equipped with multiple antennas and relies on an improved energy detector (IED). More precisely, the signals from the primary user (PU), received by multiple antennas of an SU, are fed to the IED, the IED outputs are combined using a selection combiner, and the combined signal is used to make a local decision. At the fusion center (FC), censoring of SUs is done on the basis of the quality, evaluated by the FC, of the faded R-channels. The censored decisions received at the FC are fused, using majority logic or maximal ratio combining, to obtain a final decision on the status of the PU. The performance of CSS, in terms of average miss detection probability and error rate, is evaluated considering the impact of relevant network parameters. Optimized values of the censoring threshold, as well as of the required parameters of the IED, are determined under several network conditions. The performance of the proposed IED is compared with that of a conventional energy detector.