Cognitive Radio, Cooperative Spectrum Sensing

In the wireless communications field, the spectrum efficiency is a key factor which affecting the quality of communications. Spectrum resources become increasingly tense, to promote cognitive radio technology into a new research field of wireless communications, cognitive radio can effectively alleviate the spectrum allocation and utilization to one another. Furthermore, we investigate the asymptotic performance of cooperative spectrum sensing under Gaussian fusion channels assuming large number of secondary users and samples used for local energy calculation.This paper mainly studies the cooperation spectrum sensing in cognitive radio. Through the simulation, compare different communication protocols with direct transmission of the communication performance, confirmed that in the actual communication, communication protocols are superior to non-cooperative direct transmission. Then we research and analysis of the cooperative spectrum sensing in cognitive radio networks under Gaussian fusion channels. We show that by choosing an appropriate local energy threshold, the global detection probability can be maximized under a global constraint. At last, we study that when the channels experiencing the shadow plus Raleigh fading, it's not suitable for the detection of single-node to dynamic spectrum access, namely, the cognitive users need to cooperate with each other to get favorable test results, thus to improve the spectrum efficiency and improve the network performance.