Improved Double Threshold Energy Detection for Cooperative Spectrum Sensing in Cognitive Radio

In this paper, we focus on cooperative spectrum sensing (CSS) for double threshold improved energy detector. In this method, the improved energy detector compares positive power operation p of the amplitude of received signals at each secondary user (SU) with two thresholds to make binary decision about presence or absence of primary user (PU). The energies lying between upper and lower threshold are considered unreliable and are not considered in cooperation. The decisions are forwarded over an imperfect reporting channel to a fusion center where final decision on presence or absence of PU is taken. We combine double threshold approach with improved energy detection. Two step optimization is performed where cooperative probability of detection is maximized as a function of threshold difference in double threshold and then highest value of maximized cooperative probability of detection is found as a function of power operation p, average signal-to-noise ratio at SUs, number of cooperating SUs and cooperative probability of false alarm. Also, we find the optimum fusion rule at fusion center along with optimum power corresponding p to the lowest value of the minimized total error rate using two step optimization. Then we analyse the effect of errors introduced in reported decisions due to imperfect reporting channel.