Research On Performance Optimization Of Uav-assisted Wireless Communications

In recent years,due to the miniaturization of drone models,costs have continued to decrease.Moreover,the Unmanned aerial vehicle(UAV)has the advantages of high mobility,easy deployment,ready-to-use stop,and good line-of-sight link,making research on drones a hot research topic in the world.In the era of Internet of Everything,UAVs will be a very promising technology.For example,drones can be used for air base stations,logistics,infrastructure inspections,mobile relays,weather monitoring,and so forth.In these application scenarios,research on UAV-assisted wireless communication is one of the key technical issues that need to be solved urgently.In this context,the thesis first studies the problem of UAV as the optimization of the communication performance of the air base station.Then,the UAV is further researched and optimized as a relay-assisted communication performance.The main contents of the thesis are as follows:Firstly,the thesis investigates the research background,significance and development status of UAV-assisted wireless communication performance optimization,and expounds the importance of applying UAV-assisted wireless communication in emergency scenarios and long-distance scenarios.And summarizes the main research in the thesis.Secondly,in the emergency scenario,the thesis proposes a model of Master-Slave UAV as a communication service provided by the air base station.UAVs are easy to deploy as air base stations,and can provide a wide range of fast and reliable communication services for rescue operations in emergency scenarios such as post-disaster.The coverage radius of the master UAV,bandwidth allocation,and the circular trajectory radius of slave UAV are investigated to maximize the minimum throughput of all users.Simulation results demonstrate that a significant throughput gain can be achieved by the proposed solution.And thirdly,in the scenario of long-distance data transmission,this thesis studies the wireless communication performance optimization problem when the UAV is served as a mobile relay.In this thesis,a model of mobile relay-air base station and mobile relay-observer system network is proposed,and two system network models are optimized by particle swarm optimization.That is,the flight altitude of the mobile relay,the distance between the mobile relay and the ground base station are optimized to maximize the system throughput,and the influence of the size of the system network on the throughput is analyzed.Finally,the thesis proposes future research directions and prospects.