Multiple Cumulants Based Spectrum Sensing Methods for Cognitive Radios

In cognitive radios, energy detector is considered for spectrum sensing in the literature. However, its performance deteriorates rapidly if the noise power is not known exactly. Moreover, due to the presence of a colored channel interferer or some other reasons, the conventional white Gaussian noise may become colored. In order to solve these problems, this paper proposes several multicumulant based spectrum sensing methods: generalized likelihood ratio test (GLRT) based multicumulant (GLRTMC) based detection method and multiantenna-assisted multicumulant (MAMC) based detection method. GLRTMC detection method is derived from generalized likelihood ratio test and assumed to be near optimum in theory. MAMC detection method, on the other hand, by using multiple antennas, is a complexity-reduced detector and allows us to make a compromise between performance and complexity. It is well known that cumulants higher than second order are zero for Gaussian distributions. Thus, GLRTMC detection method and MAMC detection method can extract a non-Gaussian signal from Gaussian noise even when the noise is colored. In addition, the proposed methods are nonparametric in the sense that they do not require any exact prior knowledge about the signal or the noise, such as noise power or cyclic frequencies. Hence they are immune from noise uncertainty. Simulation experiments are provided to show the validity and the superiority over single-cumulant based detector of the proposed multicumulant based detectors.