Performance Analysis And Evaluation Of Multi-tier UAV Communication Network With Directional Antenna

With significant advancements in the drone platform performance,like increased payload capacity,longer flight time,stronger space mobility and better power management techniques,drones are widely used in remote sensing information collection,traffic road monitoring,and earthquake disaster relief.At present,drones are equipped with omni-directional antennas,which have uniform gain in all directions and covered large areas.However,omni-directional antennas receive signals from various directions,they will receive severe interference from the base station during uplink transmission with ground users.At the same time,the UAV usually suffer from weight constraints,power constraints and so on,it is not suitable to install antenna array to solve this problem.Therefore,a feasible solution is to equip a directional antenna for the UAV.This paper uses stochastic geometry theory to model a multi-tier UAV network,and introduce a simple directional antenna model to analyze the downlink performance of a multi-tier UAV communication network.Connection probability is an important indicator describing whether a user can access a drone network.Due to the existence of the user receiving threshold,only drones that meet a certain distance condition can connect with the user.We assume that the user selects the drone that can provide the maximum power as the service node for communication.Under various conditions of the distance distribution of the drone,the expression of the connection probability is obtained,and the flight height,the user receiving threshold,directivity factors are analyzed through simulation.Next,based on various distance distributions and interference distributions,this paper derives closed expressions of Multi-tier UAV networks for the coverage probability.It is found through simulation that there is an optimal height to maximize the system coverage probability.At the same time,there is a trade-off between the network connectivity probability and the coverage probability.We also compared the simulation results of coverage probability with a single-layer omni-directional antenna drone network.The results show that our proposed system is superior to the above system.Our research also proves the performance advantages of the UAV equipped with directional antenna,at the same time,our research also provides practical significance and reference value for the actual deployment of multi-layer UAV networks.