无人机辅助的蜂窝数据流量卸载及保密传输方案

A cruising unmanned aerial vehicle (UAV)-assisted traffic offloading and secrecy transmission scheme is proposed to solve the problem that the uplink quality of cell-edge users is poor and easy to be eavesdropped in traditional cellular networks. Firstly, according to the line-of-sight propagation characteristics of the air-to-ground channel, a channel access mechanism based on the threshold of the received signal strength is established to solve the problem of user transmission mode selection. Then, the coverage region of UAV's link at any time is determined by considering important factors such as channel access delay, flight altitude and speed of the UAV. Additionally, an analytic formula of average accessible rate is derived and an appropriate method to evaluate the network secrecy rate is given by using the random geometry theory. Finally, the validity of the proposed scheme and theoretical results is verified by simulation experiments, and the optimal settings of key parameters are presented to achieve the optimum network performances. Simulation results and comparisons with traditional cellular networks show that the proposed mobile UAV-based networking scheme increases the uplink rate by about 40% and the security capacity by about 70% on the basis of ensuring the users fairness.