Energy Detection Technique for Spectrum Sensing in Cognitive Radio

Abstract

By using Shannon’s sampling formula, the problem of the detection of a deterministic signal in white Gaussian noise, by means of an energy-measuring device, reduces to the consideration of the sum of the squares of statistically independent Gaussian variates. When the signal is absent, the decision statistics has a central chi-square distribution with the number of degrees of freedom equal to twice the time-bandwidth product of the input. When the signal is present, the decision statistics has a non-central non-centrality parameter equal to the ratio of signal energy to twosided noise spectral density. Since the non-central chi-square distribution has not been tabulated extensively enough for our purpose, an approximate form was used. This form replaces the noncentral chi-square whose degrees of freedom and threshold are determined by the non-centrality parameter and the previous degrees of freedom.