Research On Trajectory Planning And Resource Allocation Of UAV With Single Antenna And Antenna Array

In recent years,the unmanned aerial vehicles(UAV)'s high maneuverability and low cost make it widely used in the field of wireless communication.For example,in emergency communications in disaster areas and auxiliary communications in suburbs,the use of UAVs as aerial base stations(BS)can quickly and flexibly establish a wireless communication network to ensure information transmission.In the UAV communication system,the UAV's trajectory planning and wireless resource allocation often have an important impact on the performance of the system.Therefore,this subject takes the practical application as the research background,constructs the corresponding mathematical model,and studies the optimal trajectory and resource allocation joint optimization algorithm of the UAV base station communication system under different conditions.The main innovation of this paper is the introduction of multiple antenna arrays in the UAV communication network,which causes the transmission performance of the communication network to be affected by the angle of incidence,which makes the problem highly nonlinear and extremely difficult to solve.At present,there is no literature to study this problem.To this end,this paper proposes an iterative solution algorithm based on block coordinate rotation descent and continuous convex approximation.It includes the following research contents.(1)For single-antenna UAV,the downlink transmission service based on frequency division multiple access is studied.In order to maximize the minimum throughput of multiple ground users,a joint optimization problem of UAV flight trajectory and user bandwidth is considered under the constraints of energy and flight time.This problem is often difficult to solve due to the nonlinear coupling between trajectory and bandwidth and the non-convex nature of energy constraints.Therefore,this paper proposes a two-layer iterative algorithm based on block coordinate rotation descent and continuous convex approximation.First,the trajectory design problem and the bandwidth allocation problem are decoupled by the block coordinate rotation descent method,and then iteratively solved.Among them,the trajectory optimization sub-problem is still a non-convex problem,so it needs to be further simplified by using a continuous convex approximation.(2)For UAVs based on antennas array,the downlink transmission services based on space division multiple access are studied.Consider an unmanned aerial vehicle equipped with an array antenna.During the process of flying from a starting position to a predetermined end position,two different precoding technologies,maximum ratio sending and zero-forcing,are used to transmit data to multiple ground users at the same time.Under the conditions that the UAV's flight status and flight time are limited,the goal is to maximize the system's transmission rate,and consider the joint optimization of flight path and user power allocation.This problem is difficult to solve due to the nonlinear coupling between track and power.Therefore,this paper proposes an algorithm based on block coordinate rotation descent and continuous convex approximation.First,the trajectory design problem and the power allocation problem using the two precoding techniques are decoupled by the block coordinate rotation descent method,and iteratively solved.Among them,the trajectory optimization sub-problem and the power optimization sub-problem are still non-convex problems,so the continuous sub-problem needs to be used to further simplify the corresponding sub-problems.The simulation results show the effectiveness of algorithms proposed in this paper,and give the optimal trajectory planning and resource allocation of the UAV in two scenarios.The research content and results of this paper enrich the research connotation in the field of UAV communication,and have important significance for promoting the application of UAV-assisted wireless networks.