UAV-Net:Effective And Efficient UAV Network Deployment For Extending Cell Tower Coverage

In recent years,the mobile data traffic shows explosive growth.At the same time,users often encounter network bandwidth shortage or network instability in many realistic scenarios.The flexible unmanned aerial vehicle base stations(UAV-BSs)provide a novel and promising solution to the network bandwidth shortfall problem.It is significant to study how to deploy multiple UAVs in an efficient way to maximize the total realistic throughput of clients randomly distributed in different locations.A basic idea to solve the above problems is to use ray tracing simulations as a hint to narrow down the search space for the physical measurements of UAVs.On this basis,this paper formulates two key sub-problems:chunk selection problem,which uses the simulation throughput obtained from ray tracing simulations to find an optimal subset of chunks in this region as the search space of UAVs after we divide the area into discrete points and chunks,and chunk search problem,which carries out path planning for multiple UAVs to traverse the discrete points in the selected chunk subset and conduct physical measurements.In this paper,the NP-hard properties of both sub-problems are analyzed,and efficient heuristic algorithms are proposed to solve them accordingly.A prototype system named UAV-Net is designed and implemented using a UAV mounted WiFi Access point(AP)to conduct physical measurements in a real campus scenario.Extensive simulations and physical measurements are combined to analyze the performance of proposed algorithms and other baseline methods,and the results show that the proposed methods can obtain ideal throughput gains with a relatively small measurement overhead and time consumption.