Cooperative Spectrum Sensing using Majority Fusion Rule in Cognitive Radio Networks

In cognitive radio networks, the secondary users can use the frequency spectrum when the primary users are not present. To utilize the primary user's spectrum, secondary user has to sense the spectrum continuously and detect the presence or absence of the primary user. In cooperative spectrum sensing, the performance of spectrum sensing depends on the fusion rules used at the fusion center. In this paper, we considered the Majority fusion rule to identify the presence or absence of the primary user. We calculated the optimal number of cooperative secondary users by maximizing the energy efficiency and we obtain the mathematical expression for number of secondary users using Majority fusion rule at the fusion center (FC). We showed that cooperating all secondary users in the network does not necessary achieve the optimum performance, but instead, it is achieved by cooperating a certain number of users with the highest primary user's signal to noise ratio.