Threshold Adaptation Using Non-linear Optimization for Transmission Rate Enhancement in Cooperative Spectrum Sensing

In this paper we have studied the threshold adaptation for energy based spectrum sensing in cognitive radio using non-linear optimization. Several methods to decide the threshold have been proposed in the literature such as fixed threshold, double threshold and adaptive threshold etc. Instead of using these methods to decide threshold in energy detection, an adaptive threshold has been proposed by researchers that varies according to the Signal to Interference plus Noise Ratio (SINR) experienced at Secondary User (SU) receiver to maximize the average transmission rate of secondary user while keeping the average probability of missed detection within predefined level. However in the existing scheme, the threshold is considered as a linear function of SINR to maximize the average transmission rate of secondary user. It has been observed that the use of a non-linear function in place of a linear one produces better performance. In this paper we use non-linear increasing function to find threshold in terms of SINR for cooperative spectrum sensing in cognitive radio. The simulation results on MATLAB show that the average transmission rate can be increased in cooperative spectrum sensing in comparison to the non-cooperative spectrum sensing. Also, in cooperative scenario, the proposed non-linear policy function yields significantly better results than the linear policy function in low SNR conditions.