Research On Performance Of Cognitive Radio Network Based On Wireless Caching

In recent years,the proliferation of smart mobile devices has resulted in an explosive growth in mobile network data traffic.Thousands of times of traffic growth and massive connection devices make the current wireless network face challenges from spectrum resources to network architecture.In order to improve the utilization of spectrum,this thesis combines the content caching technology with cognitive radio technology,and studies the cooperative cognitive radio network based on content caching in theory,aiming at achieving a win-win cognitive radio network.The main contents and innovations of this thesis are as follows:1.Based on the secondary base station with the cache capability,firstly,this thesis models the characteristics of the cooperation cognitive radio network.Then,starting from the caching strategy and transmission mode of the primary and secondary systems,the successful transmission probability is considered as the research metric.Under the premise of satisfying the primary user's successful transmission probability,the successful transmission probability of secondary user is taken as an optimization target.Furthermore,this thesis proves that the approximation problem has the concavity and convexity about the cache threshold by the method of approximating the original problem and the convex optimization theory.By further analyzing the characteristics of cache capacity and spectrum allocation,we propose an efficient two-level bisection algorithm.Finally,the simulation results show that compared with the traditional caching strategy and collaboration scheme,the content caching collaboration scheme proposed in this thesis achieves better performance.2.This thesis studies the performance of the secondary system based on the threshold caching strategy,aiming to maximize the effective data transmission rate of the secondary system by reasonable allocation of cache resources.On this basis,firstly,we propose a scheme based on time slot allocation for multi-base stations to serve multiple users,and formulate optimization problems.Secondly,we propose an algorithm combining exhaustive search method and two-level bisection algorithm to solve the optimization problem.Finally,the performance of multiple secondary base station cooperative and non-cooperative transmission schemes is compared.The simulation results show that the cooperative transmission scheme can achieve a greater effective transmission rate.3.Under the condition of considering the power allocation of the secondary base station,combined with the most popular file caching strategy,firstly,a problem of jointly optimizing the cache capacity and power allocation of the secondary base station is proposed,which is the maximum the effective transmission rate of the secondary user under the constraint of the minimum data transmission rate of the primary user.Then,the effect of caching and power allocation on the transmission rate of secondary user content is studied.Through further analysis,we propose an effective bisection algorithm to solve the optimization problem.Finally,experiments have shown that cache-enabled cooperative transmission is superior to uncooperative transmission.