Research On Cooperative Relay Selection And Power Allocation In Cognitive Radio System

The electromagnetic radio spectrum is limited and non-renewable resouece. In recent years, with the rapid development of wireless communication, the contradiction between the shortage of the spectrum resources and the huge demand for spectrum resources becomes a significant problem. Cognitive radio has been proposed as a new technology to promote the efficient untilization of the spectrum by exploting the spectrum holes. It can improve the system throughput and signal to noise ration remarkblely in the condition that the relay selection and power allocation are settled reasonablely. In this paper, in order to improve the spectrum utilization efficiency, joint relay selection and power allocation algorithm is considered in relay cooperation cognitive radio network.In this paper, relay cooperation problem in cognitive radio is firstly analyzed, and relay coordination communication principle is studied. The relay cooperation protocol is also conducted.What’s more, we list the types of relay selection, and give a brief introduction on spectrum sharing model based on relay cooperation. And joint relay selection and power allocation model is discussed. Meanwhile, cognitive radio hardware and software platform are proposed.Secondly, trust parameter is proposed on the basis of analyzing various factors in single relay cooperative spectum sharing environment. What’s more, the relationship between trust parameter and mis-detection probability is firstly presented. The system throughput is defined as the optimization target and a signle relay selection and power allocation model in underlay spetrum sharing is conducted. A suboptimal algorithm called cross iteration algorithm is used to solve the problem. Simulation results show that the sensitivity of the joint relay selection and power allocation model is increasing by trust parameter, and the system throughput has been significantly promoted by the suboptimal algorithm which is better than other optimal methods without trust parameter and mean power algorithm.Finally, multiple relay selection and power allocation scheme is introduced aiming at overcoming the weakness of system performance with single relay cooperation. And multiple relay selection and power allocation is simplified as relay selection problem. In this paper, with the goal of maximizing signal to noise ratio, artificial bee colony algorithm is proposed and can obtain an effective result.What’s more, simulations show that the performance of multiple relay selection scheme based on artificial bee colony algorithm has shorter simulation time and lower complexity and can achieve higher system throughput, which is better than exhaustive search, single scheme.