  In this paper a novel unmanned aerial vehicle aided (UAV) cooperative jamming
scheme is proposed for covert communications. We first analyze the detection
performance of the system to obtain the minimum error detection probability of
the eavesdropper and then determine the transmission rate as the objective
function by analyzing the transmission outage probability of the communication.
The problem formulate is non-convex that is difficult to solve. To solve this,
two efficient algorithms are proposed for general signal to interference plus
noise ratio (SINR) and high SINR, respectively. The first algorithm applying
the block coordinate descent (BCD) to decompose the problem into two
subproblems and then solve them by successive convex approximation (SCA). For
the second algorithm, we use a geometric method(GM) based on the Apollonius of
Sphere to solve the optimization problem. The proposed scheme can enhance the
covert performance significantly. Simulations verify that the proposed joint
design can enhance the covert transmission rate of the considered system as
compared to the benchmark schemes.
