Cooperative Spectrum Sensing with Transmit and Relay Diversity in Cognitive Radio Networks

In the letter the problem of cooperative spectrum sensing is investigated in cognitive radio (CR) networks over Rayleigh fading channels. By taking into account the error effect on the decision reporting, a general performance analysis of cooperative spectrum sensing is given. The analytical detection results show that the performance of cooperative spectrum sensing is limited by the probability of reporting errors. To deal with this limitation, we propose a transmit diversity based cooperative spectrum sensing method. By regarding multiple CRs as a virtual antenna array, space-time coding and space-frequency coding are applied into CR networks over flat-fading and frequency-selective fading channels, respectively. Moreover, we propose a relay diversity based cooperative spectrum sensing approach to increase the diversity of detection when some CRs are in heavy shadowing. It is then shown that, when combined with algebraic coding, relay diversity can further improve the cooperative spectrum sensing performance.