Cooperative spectrum sensing with square law combining diversity reception

Cognitive radio (CR) technique is useful for to know the uses of radio spectrum. CR is used to sense the spectrum periodically to know the primary user activity in fading environment. Cooperation among multiple CRs helps to enhance the reliability of detection of the primary user (PU), to overcome the unreliable decision by a single CR due to channel uncertainties. Along with the Co-operation of multiple users, diversity techniques are often used to reduce the fading the effect as well as to increase the detection probability. In this paper, we have consider first with no diversity case, and extended to the square-law combining (SLC) diversity technique when wireless users experience different fading channels like (Rayleigh, Rician, Nakagami, Hoyt and Weibull) in the communication channel. The method used in this is, Cooperative spectrum sensing (CSS) with Energy detection over various fading channels using SLC diversity scheme. Finally, performance evaluation is exhibited using receiver operating characteristics (ROC) curves which are drawn between P_f vs P_d for different numbers of diversity branches, various values of average SNRs, time band width product and different values of fading parameter. It is observed from the simulation is that the Weibull fading performance is better than other fading channels while SLC diversity is used.