Distributed Spectrum Sensing with Two-Stage Detection for Cognitive Radio

In this paper we investigate spectrum sensing for cognitive radio (CR) by using multiple spectrum sensors. We explore sensing schemes based on soft information combining, hard information combining and a two-stage detection scheme that uses both soft information combining and hard information combining. The two-stage detection scheme is shown to provide improved performance compared to sensing based on either hard information combining or soft information combining alone with a trade-off of sensing time. Computer simulation results are provided to validate the concept.