Study Of Key Technologe In Cognitive Radio--Spectrum Decision

With the increasing scarcity of spectrum resources, it has become an issue of most concern to improve the spectrum utilization efficiency. Cognitive radio technology (Cognitive Radio, CR), which has been proposed to solve this problem, has been widely studied in recent years and has become one of the hottest technologies in the field of wireless communication. Cognitive radio technology allows the Secondary Users(SU) to sense and occupy the ’spectrum holes’ to improve the spectrum utilization, without causing harmful interference to the Primary Users(PU).As one of the key technology of cognitive radio, spectrum decision mainly address the problem of suppressing interference to the PU caused by SU and maximizing the utilization of’spectrum holes’. Focusing on the spectrum analysis and spectrum selection in spectrum decision, the main contents of this paper is the analysis of collision interference model and throughput expectation of SU under the strategy of sequential spectrum selection, and the proposition of respective throughput optimization solutions and algorithms. The main contribution of this paper is described as follows:1) This paper summarizes and analyses the existing model of the collision interference from SU to PU, then improve the collision interference model and propose a corresponding sensing frame optimization scheme, which can bring higher SU’s throughput. The interference to PU is mainly influenced by the sensing frame structure of SU, in the scenario, which is that SU sense and access spectrum by periodically sensing. So, it is necessary for an accurate model analysis to the interference. In this paper, collision interference in the scenario mentioned above is analyzed more accurately than the ones analyzed in references, and then we propose an optimization scheme that can obtain higher SU’ throughput.2) This paper analyses and discusses the throughput expectation of SU under the strategy of sequential spectrum selection, sensing and access, and proposes to several algorithms to solve the throughput optimization problem. In the mentioned scenario, the throughput optimization problem is an NP-Hard problem, so the problem is degraded into multiple local optimization problems in this paper. A short-sight and one-step forward algorithm are proposed to solve the multiple local optimization problems. Based on the theory of simulation annealing, this paper also proposed simulated annealing based algorithm. Performance of the three algorithms above were simulated and analyzed by theoretical values and simulations of SU access model.