Research On Spectrum Allocation Algorithm In Cognitive Radio Based On Graph Coloring Theory

Nowadays, wireless networks generally use the fixed spectrum allocation mechanism, most spectrum resources are authorized spectrum, and this means that only authorized users can use them. A research result from American Federal Communications Commission(FCC) showed that with the change of time and space, authorized spectrum utilization is 15% ~ 85% in the fixed allocation mode. The efficient spectrum allocation has become an important subject. This paper is to make more cognitive users join in the authorized spectrum to increase the system utility and utilization rate in the fixed spectrum allocation mechanism.(1) This paper introduces the cognitive radio, cognitive network and the concept of cognitive radio network. Describes in detail the cognitive principle and the cognitive process of cognitive radio, cognitive radio spectrum allocation principle and a variety of techniques, as well as the similarities and differences between these technologies.(2) Based on graph coloring theory, the minimum time overhead spectrum allocation algorithm. Existing in the study of cognitive radio spectrum allocation, are assuming already satisfy the spectrum and under the premise of safe distance, do not need to distance judgment and spectrum of cognitive users filtering. In this paper we put frequency range and safe distance in the system to further perfect the process of cognitive radio spectrum allocation.(3) Established the largest efficiency improvements based on the theory of graph coloring spectrum allocation algorithm. Search in the interference spectrum allocation matrix without benefit of cognitive user priority for spectrum allocation, and then in the channel of the cognitive users generate interference, makes the channel can avoid natural side and other cognitive interferences with cognitive users have access to the user.Validated by the simulation analysis, based on the theory of graph coloring the smallest spectrum allocation algorithm greatly reduces the time cost of spectrum allocation of time overhead, improve the cognitive users access rate; Maximum efficiency improvements based on graph coloring theory and spectrum allocation algorithm with the increase of the number of users and frequency spectrum, of the total cost of the system efficiency advantage will be more and more obvious.