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

Abstract

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 an area 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 while avoiding being detected by a warden (Willie), where location uncertainty exists at Bob and/or Willie. In order to enhance the considered covert communication performance, we 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.Index Terms-Covert communication, UAV networks, trajectory optimization, transmit power, location uncertainty.Recently, unmanned aerial vehicles (UAVs) have been extensively used in wireless communication networks, due to their controllable mobility, on-demand deployment, and lineof-sight (LoS) air-to-ground link (e.g., [1]). For example, a UAV can be used as an airborne wireless communication platform such as mobile base station (BS) to rapidly recover communication service or to enhance communication quality (e.g., [2]-[6]). It can also be utilized as a mobile relay to provide a wireless connection between two or more remote users without the need for a reliable direct communication link (e.g., [7]-[9]). Furthermore, a UAV can conduct mobile data X. Zhou is with the

Robust Trajectory and Transmit Power Optimization for Secure UAV-Enabled Cognitive Radio Networks

“…Thus, in the considered UAV-enabled CR network, we not only focus on the robust design based on the bounded location error model, but also consider the robust design based on the probabilistic location error model. For the latter model, the location errors are captured by a probability distribution [21], and outage probability constraints are proposed to replace the excessively conservative worst-case constraints adopted in the existing robust designs. Under this model, UAV-enabled CR networks can achieve better performance.…”

“…According to the work in [21], it is assumed that the locations of each PU and each Eve are stochastic and follow the Gaussian distribution due to the estimation errors. Specifically, x and y coordinates are independent and identically distributed (i.i.d.)…”

“…means that the outage probability of mutual information for each Eve being larger than β n should be lower thanρ. Then, by introducing the slack variables α n , n ∈ N , a lower bound value of problem (21) can be obtained by solving the following problem:…”

Optimization of distributed detection in energy harvesting wireless sensor networks with multiple antenna fusion center

“…Here, we will show how to find W t , such that the probability of detection is maximized for a given probability of false alarm. According to (17), the threshold required to achieve P FA = fa is ′ t = −X t ln fa .…”

“…Zhou et al studied covert communications in the context of UAV networks, trying to cover a UAV for transmitting critical information out of an area that is observed and where communication is unauthorized. Specifically, the UAV as a transmitter intends to transmit information to a legitimate receiver (Bob) covertly while avoiding being detected by a warden (Willie), where location uncertainty exists at Bob and/or Willie.…”