Physics

Channel (broadcasting)

Trajectory

Trajectory optimization

Mathematics

Transmitter power output

Biology

Algorithm

Mathematical optimization

Astronomy

Geodesy

Regular polygon

Convex optimization

Optimization problem

Philosophy

Paleontology

Benchmark (surveying)

Geography

Geometry

Constraint (computer-aided design)

Covert

Context (archaeology)

Computer science

Linguistics

Transmitter

Transmission (telecommunications)

Telecommunications

Optimal control

IEEE Transactions on Signal Processing

This work considers covert communications in the context of unmanned aerial vehicle (UAV) networks, aiming to hide a UAV for transmitting critical information out of a scenario that is monitored and where communication is not allowed. Specifically, the UAV as a transmitter intends to transmit information to a legitimate receiver (Bob) covertly in order to avoid being detected by a warden (Willie) with location uncertainties at Bob and/or Willie. In order to enhance the considered covert communication performance, we prefer to jointly optimize the UAV's trajectory and transmit power in terms of maximizing the average covert transmission rate from the UAV to Bob subject to transmission outage constraint and covertness constraint. The formulated optimization problem is difficult to tackle directly due to the intractable constraints. As such, we first employ conservative approximation to transform a constraint into a deterministic form and then apply the first-order restrictive approximation to transform the optimization problem into a convex form. By applying the successive convex approximation (SCA) technique, an efficient iterative algorithm is developed to solve the optimization problem. Our examination shows that the developed joint trajectory and transmit power optimization scheme achieves significantly better covert communication performance as compared to a benchmark scheme.

Joint Optimization of a UAV's Trajectory and Transmit Power for Covert Communications