Performance Analysis of Cooperative Spectrum Sensing under Constrained Scheme

In cognitive radio networks, cooperative spectrum sensing is employed to detect the presence of primary user quickly. In this paper, we study the improvement on sensing performance for a cognitive user U₁ by allowing another cognitive radio user U₂ to act as its relay, when there is transmit power constraint for the relay U₂. We first propose a novel numerical model for sensing performance analysis, the feasibility of our model is well explained and supported by extensive simulations. We then discuss impacts of different parameters on the improvement of sensing performance. We find that the value of impacts the improvement on sensing performance significantly (and are, respectively, the path loss exponent in the channel from a cognitive user to another cognitive user and the path loss exponent in the channel from the primary user to a cognitive user). Additionally, it is difficult for U₁ to achieve the improvement on sensing performance if transmission power of cognitive users is much smaller than that of primary user.