Research On Energy Efficiency Of Uav-assisted Cellular Network Communication System Based On D2D Scene

With the advent of the era of the Internet of Everything,the development and deployment of massive machines and mobile communication equipment,the future communication data will show a large-scale and high-speed growth trend.How to deal with future communication congestion,communication security and other issues is a very valuable research direction.UAV-assisted wireless communication is a relatively cutting-edge research direction in the field of communication,and it is an indispensable potential technology in 5G mobile networks.There are many problems and challenges in the practical application of UAVassisted wireless communication technology,among which the endurance problem is an important problem that needs to be solved urgently.At the same time,due to the increasing high-performance requirements for data transmission and the shortage of spectrum resources in current device communication,the Device-to-Device(D2D)communication technology has been recognized as an important tool to improve unmanned aerial vehicle(Unmanned Aerial Vehicle).,UAV)is an effective method to assist the network backhaul efficiency,but it also brings interference and reduces the communication rate.Therefore,how to balance the system throughput and energy consumption is a problem worth studying at present.Based on the above background,this paper studies the energy efficiency optimization of the UAV-assisted cellular network communication system in the D2 D scene.In addition,considering the safety issues brought by the flight characteristics of UAVs,the optimal energy efficiency of UAVs in 3D scenarios is studied.Firstly,this paper studies the energy efficiency optimization problem of UAVassisted cellular network communication system in D2 D scene based on the twodimensional flight trajectory model of UAV,and models the problem.According to the energy consumption constraints,link scheduling constraints,UAV motion constraints,and maximum power constraints of the system,a feasible set of optimization variables is established,and under this premise,an optimization problem with maximizing the energy efficiency of the communication system as the objective function is established to jointly optimize User scheduling,transmit power and UAV trajectories.Because this problem is a non-convex mixed integer fraction optimization problem,it is difficult to solve directly.By equivalently transforming the original problem into multiple sub-problems,using continuous convex approximation technique,Dinkelbach method and block coordinate descent algorithm,this paper proposes an efficient iterative algorithm,and combines the penalty algorithm to deal with the introduced binary integer variables to obtain suboptimal untie.The simulation results show that this scheme has a great improvement in system energy efficiency compared with the reference scheme.In order to better fit the actual scene,consider the issue of UAV safety communication,and plan a more flexible and practical UAV trajectory.The current UAV air-to-ground channel model generally adopts the traditional free space fading model,which cannot better evaluate the actual channel conditions.Therefore,based on the three-dimensional flight trajectory,combined with the influence of the UAV height change on the channel model,a three-dimensional channel model related to the Rice coefficient is constructed,and the Rice channel is related to the pitch angle between the UAV and the user.Based on this channel model,the UAV-assisted cellular network communication system is determined,a joint optimization problem is constructed with the goal of maximizing the system’s safe communication energy efficiency,and an iterative algorithm is proposed.Combined with the simulation results,the proposed scheme can greatly improve the energy efficiency of system security communication compared with the benchmark scheme.