Abstract: In this Project emphasis has been laid on the study of cognitive radio technology and its spectrum sensing techniques. Here local spectrum sensing will be performed using energy detection procedure under two different kinds of environment namely-Additive White Gaussian Noise (non-fading) channel and Rayleigh Fading channel. The simulations will be done using MATLAB version 7.9.0(R2009b). From the results obtained, we will figure out the variations caused under fading environment when compared with that of non-fading environment. And thereafter the performance will be checked under collaborative spectrum sensing.