Cognitive Radio Spectrum Allocation Based On Intelligent Water Droplet Algorithm

With the continuous development of science and technology,society has entered the information age.The application of radio has been involved in all aspects of human life,radio communication facilities need to communicate through the wireless spectrum.Today,with the rapid development of radio technology,the radio spectrum resources are increasingly scarce.There are two main reasons for the shortage of radio spectrum.First,the spectrum is non-renewable resources,once the radio spectrum is allocated,that is,there is no re-allocation of spectrum resources to authorized users.Second,the radio spectrum by the relevant departments of the state using static spectrum allocation,spectrum allocation to fixed departments or users.Even in these authorized spectrum idle state,other departments or other users can not use.Under the existing static spectrum allocation policy,the utilization rate of a large part of the allocated spectrum resources is low.The emergence of cognitive radio can alleviate the problem of spectrum resource shortage.It can detect the unoccupied spectrum according to the changes of external wireless environment.And can access the spectrum in the way of " see hole pin",which improves the utilization rate of radio spectrum to a certain extent.In view of the low utilization rate of spectrum resources caused by static spectrum allocation,this paper introduces several algorithms of cognitive radio dynamic spectrum allocation and their principle and application process.Intelligent water drop algorithm has the advantages of simple principle,easy implementation,strong robustness less computation and avoiding falling into a local optimal solution.This paper applies intelligent water drop algorithm to cognitive radio spectrum allocation.In spectrum allocation,the algorithm not only considers the influence of cognitive users(also called secondary users),but also considers the influence of cognitive users on authorized users(also called primary users).When an authorized user uses spectrum communication,if the cognitive user can use the channel of the authorized user without causing interference to the cognitive user,the spectrum utilization mode can improve the utilization rate of spectrum resources.In this algorithm,in order to increase the convergence rate and find the better solution effectively,the evaluation function is adjusted and the penalty function is added.The experimental results show that the algorithm based on intelligent water droplets can get better allocation results and faster convergence rate in spectrum allocation,which can improve the utilization efficiency of cognitive radio spectrum resources to some extent,and also improve the fairness of cognitive user system.In order to further improve the efficiency of spectrum allocation,the intelligent water drop algorithm is further improved.The advantages of tabu search algorithm,such as strong climbing ability,flexible memory function,better searching ability,are combined into the intelligent water drop algorithm.The improved hybrid intelligent water drop algorithm is used to solve the spectrum allocation problem.So that the initial solution obtained by intelligent water drop can get more candidate solutions through a series of changes,increase the diversity of understanding,and improve the performance of the algorithm.The results show that the hybrid intelligent water drop algorithm has strong vitality,not only can improve the convergence speed to the optimal solution,but also the system efficiency and system fairness in cognitive radio.