Narrowband Spectrum Sensing for Different Fading Channels for Cognitive Radio Networks

I. INTROEDUCTION The CR wireless network is intended as an advanced technology integration environment with a motivation on making adaptive, spectrum efficient systems with emerging programmable radios.Wireless communication phenomena are mainly due to scattering of electromagnetic waves from surfaces or diffraction over and around buildings[1]. The communication channels are required to design such a way that make the received power sufficient to overcome background noise over each link.Minimization of interference to other more distant links operating at the same frequency is also required. Each transmitted signal cross a different path to reach to receiver due to presence of reflection in the environment. The sight of reflector causes multiple path and during traveling each signal on each path will go through different delay,attenuation and phase shift which causes constructive and destructive fading. Fading channel models are frequently used to image the effects of electromagnetic transmission of information. The narrowband channels are called flat fading channel as the coherence bandwidth of the channel is greater than the bandwidth of the signal. Rayleigh, Rician and Nakagami fading models are used to reduce the fading of these channels. In this paper, narrowband spectrum sensing for different fading models are considered. First we use BPSK modulated signal. Then observe the probability of detection(Pd) and probability of false alarm(Pf) over Rayleigh fading channel. Then we apply Rician fading channel. At last we observed the performance of Nakagami fading channel. We calculate their energy and compare the energy value with a threshold value. We also observe their receiver operating characteristics(ROC) curve and complementary receiver operating characteristics (CROC) curve. We observe their performance by their ROC and CROC curve. Finally we compare Rayleigh, RicianandNakagamifading channel depending on their performance.The remainder of this paper is arranged as follows. Different fading models are described in Section 2. System model is described in Section 3. In Section 4 thesimulation results. The conclusion is described in Section 5.