The Research Of Spectrum Sensing Technology In Cognitive Radio

With the rapid growth of the wireless communication and the increasing demand ofwireless business for People,radio spectrum resource becomes more and more scarce and theutilization rate of spectrum resources is very low. The core ideology of cognitive radiotechnology is through the sensing free spectrum which has authorized,and then access thefree spectrum without primary users and interference,in order to improve the utilization rateof spectrum resources.Spectrum sensing play a very important role in cognitive radio,this paper mainly studiesthe spectrum sensing technology in cognitive radio,focusing on a single node energy detectionmethod and the cooperative spectrum sensing.Firstly this paper introduces the research background、significance、developing surnmaryand its studies status at home and abroad of cognitive radio,then we study the single node andcooperative spectrum sensing method.This paper analysis matched filter detection, energy detection and cyclostationary featuredetection,especially the energy detection,as the foundation for cooperative spectrumsensing.The actual communication environment exist shadowing effect, multipathing effectand fading,this paper study cooperative spectrum sensing because of these limitations insingle node spectrum sensing and study the data fusion algorithm in cooperative spectrumsensing,then two types of improved methods are studied in the thesis.One is trust weighted cooperation sensing,it is proposed to further improve cognitiveradio spectrum sensing performance with respect to the existing weighted cooperativealgorithms,a index trust function as weight,the difference of trust and the characteristics ofindex function are consided,the large weight distributed the high trust cognitive users,thesmall weight distributed the low trust cognitive users,so reduce influence of low trust users tothe results,the proposed algorithm are simulated in AWGN and Rayleigh channel,simulationresults show that the algorithm improve the detection performance effectively.This paper presents the double threshold energy cooperative detection algorithm basedon mixed adaptive weighted algorithm,with respect to the existing double threshold energydetection algorithms do not consider the impact of distance path loss to the detectionperformance,the SNR weight factor and distance weight factor were introduced to adjust theweight of double threshold in fusion center,simulation results show that the algorithmovercome the detection probability decline caused by path loss.