Cooperative spectrum sensing with diversity reception in cognitive radios

Cognitive radio (CR) is a promising technology that is capable of exploiting the scarcity of radio spectrum. One of the most important challenges for a CR system is to perform spectrum sensing in a fading environment. Diversity reception techniques are often used to combat the detrimental effects of fading channels. In this paper, we derive representations for the average probabilities of detection and false alarm when using energy detection with different diversity reception schemes over Nakagami-m fading channels. These expressions are then proved to have lower computational complexity than those proposed in the literature. The performance of different diversity reception schemes is compared for finding a proper cooperative strategy under different constraints. Simulation results show that with the aid of channel state information (CSI), maximum ratio combining gives an upper bound of the detection performance. Without CSI, square-law combining offers the best detection performance.