Research On Spectrum Sensing Technology In Cognitive Radio

In recent years, the radio spectrum resources have been decreased dramatically as the increasing need of the wireless communication services. The current spectrum allocation method, however, gives rise to numerous of unused and low utilization rate frequency bands. The cognitive radio is an effective approach to the problems above. Cognitive radio is an intelligent spectrum sharing technology, which functions as the detection of the free frequency bands in the surroundings so that they can be used effectively. Therefore, the detection of the free frequency bands are the foundation of cognitive radio, which is called the spectrum sensing technology.This paper focus on the spectrum sensing technology in cognitive radio since fast and accurate spectrum cognition is the premise of effective communication of Cognitive radio system. In this paper, we first introduce the principle as well as the advantages and disadvantages of the common spectrum sensing algorithms. Then we discuss the cyclostationary feature detection and the Maximum-minimum eigenvalue detection.and make simulations of the cyclostationary spectrum density of BPSK. signal, the cyclostationary feature detection and the maximum-minimum eigenvalue detection of BPSK signal. Through the theoretical analysis and experimental simulation, we find that the cyclostationary feature detection does overcome this defect, but with a high complexity of calculation. Meanwhile, the maximum-minimum eigenvalue detection has both the advantages of simpler calculation and less effect of the noise, but it works poorly in the situation of a low SNR. Based on the cyclostationary feature detection and Maximum-minimum eigenvalue detection, this paper brings up a combination of the two approaches. Finally we make simulations of the improve spectrum sensing algorithm, and this results in the significantly improve of the performance according to the simulation results, with a relatively low complexity of the calculation...