Cognitive Radio Networks Dynamic Spectrum Allocation To Technology Research And Implementation

With the development of wireless communication technology and the current wireless applications continueing to expand as described in literature,the lack of spectrum resources becomes a urgent problem in the process of research in wireless applications. However, some studies suggest that the large number of precious spectrum resources has not been fully utilized currently, and even in many cases is idle. In order to effectively address the problem of scarce spectrum resources, a new spectrum usage pattern--- Cognitive Radio (CR) are gradually being people's attention.The main contents of this thesis is spectrum allocation of dynamic spectrum management in the cognitive radio system. First, a summary and an overview of two kinds of spectrum sharing models--- Overlay model and Underlay model are given. And the interference temperature model led by underlay model is introduced. Then, this paper describes a graph theory represented by the centralized spectrum allocation model theory, as well as game theory, represented by a distributed spectrum allocation model theory. Later, this paper deals with spectrum allocation algorithm in two ways of centralized and distributed separately based on interference temperature model.The focus of this paper is the fourth chapter. Through the research we found that there is no article that has yet considered the primary user activity in spectrum decision. To describe the primary user activity in CR networks, a new metric - up-time ratio of spectrum is proposed in this article, which is defined as the ratio of occupancy within one day to the whole time,reflecting the level of usability of spectrum for secondary users. Taking fully account of the main user activities impacting on cognitive user activitise, a Spectrum Decision based on Up-Time Ratio of spectrum (SDUTR) is presented, which puts key focus on reducing collision on the licensed spectrum between the primary user and the secondary one and can operates over heterogeneous spectrum bands. Moreover, Simulations show that transmitting over the minimum channel set solved by SDUTR can reduce broadcasting delay and cut down information redundancy as compared to selective broadcasting. Besides, available unallocated channels will be used as standby channel set as collision between the primary user and the secondary user occurs. Meanwhile, the theoretical analysis and simulation results of the same algorithm also proved correct.