Study And Analysis Of Spectrum Sensing In Cognitive Radio

As radio spectrum resource is becoming increasingly scarce, Cognitive Radio (CR) arises as a hot research topic in wireless communications, because it is believed that CR is a potential solution for the contradiction between spectrum allocation and usage. Spectrum sensing, one heart technique in CR, plays a vital part in CR realization.This paper introduces the concept and research work at home and aboard of CR, based on which the focus of this paper is established. Three spectrum sensing techniques are compared, and the theory of energy detector is emphasized. Then Multi-taper method and WOSA method are compared, and the Multi-taper method in the performance of its parameters is analyzed. Finally, based on the detection of the energy spectrum perceived by simulation and analysis, the energy detection is an effective detection of the spectrum sensing method.We consider the problem of spectrum sensing by using multiple antenna in cognitive radios when the noise and the primary user signal are assumed as independent complex zero-mean Gaussian random signals. The optimal multiple antenna spectrum sensing detector needs to know the channel gains, noise variance, and primary user signal variance. In practice some or all of these parameters may be unknown, so we derive the Generalized Likelihood Ratio (GLR) detectors under these circumstances. The proposed GLR detector, in which all the parameters are unknown, is a blind and invariant detector with a low computational complexity. We also analytically compute the missed detection and false alarm probabilities for the proposed GLR detectors. The simulation results provide the available trade-off in using multiple antenna techniques for spectrum sensing and illustrates the robustness of the proposed GLR detectors compared to the traditional energy detector when there is some uncertainty in the given noise variance.