A two-stage cooperative spectrum sensing method for energy efficiency improvement in cognitive radio

Cooperative spectrum sensing (CSS) can improve the performance of spectrum sensing greatly in cognitive radio (CR), however, the energy consumption in CSS also increases because there are more second users taking part in spectrum sensing. To improve the energy efficiency while maintaining the sensing accuracy to a desired threshold, we propose a simple and practical CSS method called two-stage cooperative spectrum sensing. We seek to improve the energy efficiency by decreasing the average number of SUs carrying out spectrum sensing, so we divide the sensing procedure into two stages and let it stop at the first stage if the channel is sensed as occupied. Then particle swarm optimization (PSO) algorithm is introduced to maximize the energy efficiency. Simulation results show that the convergence performance of our method is quite good and the energy efficiency of our method is significantly improved compared with the single-stage CSS.