Energy and throughput efficient strategies for cooperative spectrum sensing in cognitive radios

An efficient cooperative spectrum sensing based cognitive radio network employs a certain number of secondary users to sense the spectrum while satisfying a constraint on the detection performance. We derive the optimal number of cognitive radios under two scenarios: an energy efficient and a throughput optimization setup. In the energy efficient setup, the number of cooperating cognitive radios is minimized for a k-out-of-N fusion rule with a constraint on the probability of detection and false alarm while in the throughput optimization setup, we maximize the throughput of the cognitive radio network, by deriving the optimal reporting time in a sensing time frame which is proportional to the number of cognitive users, subject to a constraint on the probability of detection. It is shown that both problems can be simplified to line search problems. The simulation results show that the OR and the majority rule outperform the AND rule in terms of energy efficiency and that the OR rule gives a higher throughput than the AND rule with a smaller number of users.