A novel asynchronous cooperative spectrum sensing scheme

Cooperative spectrum sensing is a promising technology for spectrum sensing with superior performance. Previous work has assumed that secondary users (SUs) are synchronous with the primary users´ (PUs) network. However, on one hand, the SUs may have no information about the PUs´ communication protocols. On the other hand, in some cases communications among PUs are not based on synchronous operation. In order to address such problems, an asynchronous cooperative sensing scheme is proposed. In this scheme, the SUs need not synchronize with the PUs when dynamically sensing and accessing primary channels. The channel-usage pattern is modeled as an ON-OFF process and the SUs´ average throughput of each asynchronous case is analyzed based on the detection and false alarm probability. The optimal sensing period for the sensing scheme is achieved by maximizing the SUs´ average throughput. Simulation results evaluate the performance of the scheme.