Caching Strategy Based On D2D Communication In 5G Networks

The continuous growth of mobile data traffic brings a great burden to the traditional network architecture.Facing the increasing network demand,the performance requirements in different application scenarios can be met in the Fifth Generation Mobile Communication(5G)by means of large-scale Multi-inputs and Multi-outputs,small cells densification,Device-toDevice(D2D)and other technologies.D2 D communication does not pass through the base station,but directly communicates between users’ equipments which reduces the load of the macro base station.In order to reduce transmission energy consumption in 5G networks,this thesis proposes a caching strategy based on D2 D communication.Taking the “macro base station as the main and small cell as the secondary” networking in the 5G networks as the network scenario,the user’s mobility is firstly analyzed to establish the model of user’s movement between the small base stations and the impact of user movement on the communication between users.Then,with the goal of minimizing the total energy consumption of file transfer,the caching strategy is divided into two parts: content placement and content distribution.The energy consumptions of user equipment,small base stations and macro base stations in file transmission are studied,and the formulation of content placement strategy is transformed into a constrained nonlinear programming problem,which are solved by Genetic Algorithm.In the process of formulating the content delivery strategy,the selection of the receiver and the sender during the file transmission is determined,and the delivery process is studied by transforming it into the minimum-cost maximum-flow problem in the network flow.In the content placement part,this thesis takes the total energy consumption of file transmission in the community as the optimization goal,and considers the users’ mobility and the capacity limitation of the devices in the actual situation;in the content delivery part,the base station and the users’ equipments are regarded as the senders to participate in file transmission.The cache strategy proposed in this thesis is realized by the simulation program,and is compared with other existing cache strategies on performance in different file popularity,different user cache capacity and different user contact rate.The applicable scenarios of each cache strategy are analyzed.Simulation results show that the cache strategy based on D2 D communication proposed in this thesis can reduce the total energy consumption of file transmission in 5G networks.