Research On Spectrum Access Technologies Based On Markov Model In Cognitive Radio System

With the rapid development of wireless communication services, the contradiction between thewaste of numerous spectrum resources and the shortage of spectrum resources is becomingincreasingly apparent caused by fixed spectrum assignment strategies, thus cognitive radiotechnology comes into being. Through perceiving and dynamic access to the surrounding spectrum,cognitive radio system achieves the efficient sharing of spectrum resources. What’s more, spectrumaccess technology used to solve the issues of whether and how to access idle spectrum is one of themost critical technologies in cognitive radio system.The dissertation does some in-depth researches on spectrum access technologies in cognitiveradio system, and the main research context is as follows:Firstly, the dissertation has an overview of cognitive radio system, and the current researchstates are briefly introduced. On this basis, a detailed overview of spectrum access technologies aswell as corresponding prediction algorithms in cognitive radio system is given.Secondly, the probabilistic suffix tree of Markov model is used on spectrum prediction for thefirst time, in order to predict the states of channels in the next time slot by using their prioriknowledge, then a novel spectrum access algorithm based on probabilistic suffix tree is proposed,and the rationality and effectiveness of the algorithm are verified by simulation experiments.Then, considering the differences of cognitive services demands, the probabilistic suffix tree ofMarkov model is used to predict the states of channels for multi-scale, so that secondary users aregiven priority to access to the corresponding available channels. As a result, a novel spectrumaccess algorithm based on services demands is proposed, and the effectiveness of the algorithm isverified by simulation.Finally, the main conclusions of this dissertation are summarized and prospects of futureresearches are put forward.