Modeling and Performance Analysis in UAV Assisted Ultra Dense Networks

Ultra dense network (UDN) is a promising technique to meet the requirements of explosive data traffic in the fifth generation wireless system, which however often challenged by the base station offloading in extremely crowded areas. Using unmanned aerial vehicles (UAVs) to assisted terrestrial base stations is an attractive approach to solve this problem. In this paper, we research the coverage probability and area spectral efficiency in the UAV assisted ultra dense network, where stochastic geometry tool is used to model the three-dimensional locations of UAVs and derive the closed-form expressions by taking into account different channel propagation. Two subchannel access schemes, namely distributed randomly access scheme and centralized conditional access scheme are proposed to reduce the interference from adjacent UAVs. Simulation results validate the accuracy of the proposed analysis and obtain interesting tradeoffs depending on the channel propagation parameter, transmitters density and spectrum occupation ratio.