Cooperative Spectrum Sensing Exploiting a Certain Number of CR Users Based on Multi-Antennas in Cognitive Radio Networks

In this paper, a cooperative spectrum sensing scheme, which is based on cooperation of a certain number of secondary users and cooperative diversity under multi-antenna scenario, is proposed. Under multi-antenna scenario, we set a targeted detection probability and optimize the false alarm probability of the network by choosing a certain number of secondary users with the highest primary user's signal to noise ratio. The detection performance of the network is also evaluated when all the secondary users are cooperating to illustrate the benefits of the proposed scheme as a contrast. In addition, how to choose the detection threshold of the secondary user is analyzed for the purpose of decreasing the average risk. Theory analysis and simulation results show that the optimum false alarm probability can be derived by cooperating a certain number of secondary users rather than all the secondary users and the detection performance of the network can be further improved if secondary users are equipped with multiple antennas. Also, a minimum average risk can be obtained by optimizing the detection threshold.