Base Station On Rotary-Wing UAV:A Convex Optimization Approach

The civil market of Unmanned Aerial Vehicle(UAV)has been developing rapidly in recent years.China's high-tech enterprises,led by DJI,have occupied most of the UAV product market in the world.In addition to military appli cations,UAV as base station or communication relay is becoming a more and more popular research direction for the future communication system.In the region,where infrastructure has been destroyed by natural disasters,such as earthquakes and tsunamis,UAV base stations can be deployed rapidly to provide basic communication services and ensure the contact between the disaster area and the outside world.In some tourist attractions,the load of ground base station might increase dramatically due to the increase of people flow during holidays,jamming the communication service.The UAV base station can be rapidly deployed to improve the capacity of the system and provide communication services for tourists in the scenic spot,due to the high flexibility of UAV.When UAV is in different position,the channel conditions between UAV and users will be different.The battery carried by the UAV is limited.Therefore,it is necessary to optimize the three-dimensional position of the UAV,so that the UAV base station can provide better services to users,save the transmission power and the energy consumed by the movement.Based on the existing research in the field of UAV communications,the contribution of this dissertation lies in the optimization algorithm design for UAVs' locations.Under the assumption that the users appear randomly,the UAV accumulates the user's randomness after a long period of observation,and calculates the three-dimensional location of the UAV via maximizing energy efficiency in the past period of time.Moreover,combined with speed constraints,user scheduling constraints and other conditions,the three-dimensional location of UAV in the next period of time is optimized.This optimization algorithm makes the solution more practical,and can significantly improve the system performance.This dissertation starts by introducing the mathematical system model.The channel model is mainly based on Goldsmith's book of Wireless Communication and the air-ground channel model in the published literature,the user distribution model is based on the Poisson Point Process;and the energy efficiency is used as the performance metric.It is shown by numerical simulations that the proposed optimization algorithms can significantly improve the performance of UAV base stations via continuously observation of user distribution statistics and adaptation of UAVs' locations.