Cognitive Radio Resource Allocation Based On OFDM Technology

As a novel intelligent communication technology, the cognitive radio can effectively alleviate the shortage of spectrum resources which is brought by the growth of the business volume and the quality of service of the wireless communication. The resources allocation is an important technology for cognitive radio spectrum resources management. In order to maximize the system’s efficiency and incomes the utilization of the spectrum resource effectively, this paper study the resource allocation problem based on OFDM system under two cognitive radio spectrum sharing modes:Overlay and Underlay.Firstly, the research situation of cognitive radio, cognitive radio technology and the basic principles of OFDM technology are analysized and summarized. According for the high implementation complexity of classical iterative water-filling algorithm, the artificial bee colony algorithm is proposed to solve the problem of resource allocation under the Overlay mode. The food source location in artificial bee colony algorithm and the power being allocated in practical problems are corresponded. So a cognitive radio power allocation method based on artificial bee colony algorithm is proposed, Simulation results show that this method can effectively improve the limitations of indirectly optimization of the existing power allocation methods, and the power allocation problem is implement more easily.Secondly, on basis of the above study, a cognitive radio resource allocation method which uses a binary artificial bee colony algorithm to optimise transmit power and modulation hexadecimal number of cognitive users together is further proposed. The feasible solution and the transmit power and binary coded of modulation manner in this algorithm are are corresponded. Thus the optimization solution of this problem is obtained. Simulation results demonstrate that this method can effectively realize the maximization of the system benefits.Finally, a two-steps optimization strategy is used to solve the resource allocation problem under the Underlay mode. This paper propose a sub-carrier allocation mechanism which could realize the fairness between users. Then this paper also propose a capped linear water-filling algorithm with low complexity to solve the resource allocation problem. Simulation results show that the resources allocation method not only ensures the fairness between the cognitive users, but also officiently reduces the complexity of the algorithm largely.