UAV-Enabled Multi-User Covert Communications Against Active Flying and Ground Wardens
Jianyu Wei, Yan Guo, Haichao Wang, Guoru Ding, Binghan Lei
Abstract
This correspondence investigates a multi-user covert communication system, where active flying and ground wardens co-exist. Considering covertness requirement, the position uncertainty, finite observation and active jamming constraints for the multiple wardens, a general three-dimensional dynamic optimization framework assisted by unmanned aerial vehicle (UAV) is formulated to maximize the minimum average covert rate (MACR). Firstly, the effects of active jamming and covertness contraints on transmission rate are analyzed. Then, slack variables are introduced to equivalently transform the nonconvex problem. Besides, an iterative algorithm is proposed, which can optimize 3D trajectory, power and bandwidth allocation ratio simultaneously, based on S-proceduce and successive convex approximation (SCA). Simulation results reveal that the proposed algorithm can enhance the MACR significantly while the constraints being satisfied compared to the baseline algorithms.