Research On The Technology Of Spectrum Sensing Based On Dual Threshold Adaptive Algorithm Using Cyclic Spectrum In Cognitive Radio

Since1999, Dr. Mitola proposed the concept of cognitive radio, many scholarshave invested a lot in the field of research, and also with many nascent concept putforward more and more people will be more content with other disciplines recognizedresearch cognitive radio combination, such as pattern recognition, software radio,artificial intelligence, graph theory, game theory, etc., is a comprehensive study of thesedisciplines, so that cognitive radio has become a comprehensive disciplines. Alsoformed simultaneously cognitive radio technology has its own characteristics, such asspectrum aggregation, multi-carrier power distribution. Which, spectrum sensingcognitive radio technology is also a must have unique technology.Spectrum sensing technology is mainly based on needs, the state of the externalenvironment information acquisition, which can be perceived channel state, it can beperceived presence or absence of an authorized user. This spectrum sensing technologyis mainly based on the latter’s research. The traditional spectrum sensing techniques arematched filter detection, energy detection, and cyclostationary feature detection. In thispaper, the use of cyclostationarity detection method, because this method can make useof signal detection Cyclostationarity good signal and noise will be distinguished inorder to detect the presence or absence of primary users.This paper first introduces the basic theory of cyclic spectrum, while the cyclicspectrum gives an overview of the development. Then, the paper QPSK signal and thespread spectrum signal, for example, studied the use of signal detection signalCyclostationarity prove the feasibility and the derivation of the artificial signal pointexists at zero cyclic frequency peak. Meanwhile, the papers from the ideal state and theactual state of the two aspects of the noise for the cyclic spectrum perceived impact, butalso proved that the cyclic spectrum at zero point for the cycle frequency noiseinhibition.In this paper, the cyclic spectrum detection in the time domain smoothingalgorithm, based on its improvement is proposed based on cyclic spectrum sensingalgorithm adaptive dual threshold to reduce the spectrum sensing delay. This paperstudies the signal cyclic spectrum model to analyze the probability distribution functionof their obedience, and with a non-zero point energy as a cycle frequency signaldetection statistic deduced authorized users in different states under the mean andvariance, resulting in detection probability and false alarm probability and decisionthreshold relationship. This paper also considers both the FFT transform word lengtheffect introduced by rounding errors and obtained its mean and variance correctionformula. In this paper, the Bayesian criterion of the minimum cost function criterion proved its criterion is a convex optimization process, and the use of convexoptimization tools to get the optimal decision threshold. At the same time this also raisesa second decision threshold, based on the set of different degree of confidence, to obtaindifferent second decision threshold, the algorithm can detect the light of the differencevalue adaptively selected number of iterations to achieve adaptive the purpose ofreducing the amount of computation.Finally, this article demonstrates its fully meet the current estimated delayspectrum sensing mobile communication system needs through the FPGA emulationplatform for its estimated delay simulation study.