Due to the unavoidable use of mobile phone and another data communication as a result we face the problem of spectrum scarcity. Within the current spectrum regulatory framework, however, all of the frequency bands are exclusively allocated to specific services and no violation from unlicensed users is allowed.But as we know that most of the time band is either not utilized or underutilized. The...

In Cognitive Radio (CR) networks, multiple secondary network users (SUs) attempt to communicate over wide potential spectrum without causing significant interference to the Primary Users (PUs). A spectrum sensing algorithm is a critical component of any sensing strategy. Performance of conventional spectrum detection methods is severely limited when the average SNR of the fading channel between...

Cooperative spectrum sensing has proved to be an effective method improve the detection performance in cognitive radio systems. This work focuses on centralized cooperative schemes based soft fusion of energy measurements at radios (CRs). In these systems, likelihood ratio test (LRT) is optimal rule, but sufficient statistic depends local signal-to-noise (SNR) CRs, which are unknown most practi...