Optimum number of secondary users and optimum fusion rule in cooperative spectrum sensing to maximize channel throughput

In cognitive radio networks, secondary users can be coordinated to perform cooperative spectrum sensing to achieve higher detection accuracy. However, when the number of cooperative users increases, more overhead traffic of decision transmission introduced to network and throughput of cognitive radio network decreases. Furthermore, the performance of cooperative spectrum sensing is limited by the probability of reporting errors. In this paper, first we study optimal number of secondary users in cooperative spectrum sensing to maximize the achievable throughput for the secondary network under the constraint that the primary users are sufficiently protected. We formulate the optimization problem mathematically for cognitive radio networks over Rayleigh fading channels, which affects on decision reporting error. Then, we investigate the effect of fusion rule parameter on the throughput performance and develop the optimization model to increase the maximum achievable throughput. Numerical and simulation results will prove that the final optimization problem yields the highest throughput for the secondary network.