Research On Dynamic Spectrum Allocation Algorithm In Cognitive Radio

With the development of the science and technology, human’s communication by the cable into a wireless. Spectrum resource which communications demanded is becoming increasingly scarce, an urgent need to create new ways to improve the current system of spectrum management and allocation policies to address the spectrum resource’s shortage. Fixed spectrum allocation at this stage leads spectrum resource underutilized, resulting in a serious waste. According to the changes of the environment, cognitive radio can adaptively adjust the parameters itself, discovering the existence of the "spectrum holes" in surrounding environment, allocats spectrum dynamically, it allows users to access "hole" in an accidental way. It improvs the utilization of spectrum resources, and accesses the communication efficiency.Spectrum allocation issue is one of the core issues in cognitive radio resource management, the current spectrum allocation in Cognitive Radio Research widely, appeared graph theory, game theory and other classic models. Dynamic spectrum allocation algorithm for cognitive radio has been studied to achieve a greedy distributed list coloring algorithm. For algorithm demonstrated by the lack of fairness, this paper presents an improved algorithm make a better stability, and comparing analysis of two algorithms for simulation.This paper has studied the benefit of spectrum allocation algorithm, which based on user needs in order to obtain communication benefit and spectrum resources for reasons of communication, in order to maximize the benefit of the algorithm obtained for the target system. This paper proposes new ideas to improve the overall benefit of the distribution system based on the circumstances of the original algorithm considers inadequate conditions, gives a detailed flow chart of the process and the allocation of future comparative analysis of the simulation algorithm strengths and weaknesses, while improving the benefit the spectrum obtained by the user also increased, communication effect becomes more favorable.For small bandwidth spectrum cannot be used, this paper presents a non-contiguous spectrum allocation algorithm based on user needs, it improves the spectrum resources’secondary utilization in the premise of satisfying the user needs. Using OFDM technology, algorithm reallocats some of the small bandwidth and the remaining debris redistribution of spectrum resources, so that it can be accessed by cognitive users. The algorithm allocats a large segment of the spectrum at the same time taking into account the usage of the spectrum resource debris, it greatly improves the spectrum utilization and satisfies the essential requirements of the cognitive radio system.