Analysis Of Millimeter-wave Blocking Characteristics Based On Pedestrian Density And Efficient Joint Deployment Of UAVs Base Station And Users

Unmanned aircraft,due to their mobility and flexibility,can be used as aerial base stations or flying mobile terminals to provide ubiquitous connectivity to users,making them an important component of future mobile communication systems.Millimeter wave has an extremely wide transmission bandwidth and a narrow beam with good security and confidentiality.By combining the two,millimeter wave communications for UAVs will provide higher speed data rate services and wider coverage,offering a wide range of applications.However,the line-of-sight path of millimeter wave signals is highly susceptible to obstacle blockage,and dynamic blockage caused by moving human bodies in particular can have a serious impact on millimeter wave transmission quality.Current research has focused on the effect of randomly moving individual pedestrians on millimeter wave communication blocking.however,the above model is not applicable to scenarios with high pedestrian density such as commercial pedestrian streets and stations.This paper therefore investigates the millimeter wave blocking characteristics of UAVs based on a model of pedestrian movement in commercial pedestrian streets,and sets up a high-performance joint deployment of UAV base stations and users.The main contributions of this paper are as follows.(1)The millimeter wave blocking characteristics of the UAV based on the human density model are analyzed and studied: firstly,for the case where the target user is stationary,we theoretically analyze the blocking characteristics and derive a closed-form solution for the blocking probability.Secondly,for the case where both the pedestrian and the target user are in motion,resulting in real-time changes in the blocking area,we derive a blocking probability based on numerical analysis.(2)Based on the findings in(1),we investigate the efficient joint deployment of UAV base stations and target users: firstly,we conduct a theoretical analysis of the efficient joint deployment of UAV base stations and target users,and conclude that the blocking probability of millimeter wave communication is only related to the projected distance between the UAV and the target user in the direction of human traffic.Secondly,based on these conclusions,we have conducted a large number of numerical simulations to compare the blocking probability of multiple UAV base stations with different topologies,and through a comprehensive comparison,we have found that the blocking probability is lowest when the UAVs form a rectangular topology.Finally,for each topology location of the UAVs,the analysis leads to an efficient deployment strategy for the target user,i.e.when the link between the user and the UAV is parallel or approximately parallel to the direction of the human flow,the blocking probability is the lowest and the user location is the best.