Modeling And Analysis Of Millimeter Wave Communication Network Based On Multi-UAVs’ Cooperation

With its abundant continuous available spectrum resources,which makes millimeter-wave technology to be one of key technologies for the development of 5G.However,the penetration of millimeter wave signal is poor and the propagation loss is large.It is easy to introduce strong inter-cell interference when the base stations are densely deployed.The unmanned aerial vehicles(UAVs)can be deployed flexibly to avoid the obstruction and prolong the signal transmission distance.At the same time,adopting appropriate base station cooperation strategy into UAV base station can effectively suppress inter-cell interference.Hence,combining UAV Communication Technology with Millimeter-wave Technology,this thesis studies the millimeter wave cellular network built by cooperative UAV air base station,The main research work is summarized as follows:Firstly,aiming at the areas where it is difficult to deploy ground base stations,a network model using UAVs to carry air base stations to provide services for users is proposed.Considering the complex blockage effect of buildings on millimeter wave links in cities,the locations of UAV and buildings are modeled by the Poisson point process.Besides,in order to suppress the inter-cell interference and improve the quality of service,an interference coordination strategy based on almost blank subframes is adopted between UAVs base stations.Based on this model,the approximate expressions of system coverage probability and rate coverage probability are derived and verified by Monte Carlo simulation.The experimental results show that the interference coordination strategy can improve the coverage performance of the network and optimizing the deployment density and height of UAV can maximize the coverage probability performance of the system.Aiming at the dense area of data transmission,this thesis presents a network model in which cooperative UAV air base stations and ground base stations provide services to users.According to the location distribution characteristics of UAV base stations and ground base stations,the nearest Association strategy is adopted,that is,the user establishes a communication link with the nearest base station.According to geometric relationship,the association probability of users establishing communication links with UAV base station and ground base station respectively is deduced.On this basis,the average coverage probability and rate coverage probability of the whole system are further deduced based on stochastic geometry theory,which are verified by Monte Carlo simulation.Then this thesis focuses on the impact of UAV deployment height and density on connection probability and coverage probability.In conclusion,the results obtained in this thesis provide a very valuable theoretical guidance for the research of millimeter wave network performance assisted by UAV technology.