Cooperative sensing using inactive secondary users in cognitive radio system

To enhance the spectrum sensing performance in cognitive radio system, a new cooperative spectrum-sensing scheme by using inactive secondary users (SUs) is proposed. Cooperative sensing is performed among SUs only when they have data to transmit. The inactive SUs have been introduced to cooperation group in the event that there are no enough active SUs to obtain the predefined spectrum detection performance cooperatively. Both the theoretical analysis and simulation results demonstrate that the performance of the trade-off between the time period used for sensing and the achievable throughput can be improved by utilizing the inactive SUs. The optimized additional listening time for inactive SUs can be obtained after the weights of the achievable throughput and the efficiency are determined.