Timeliness-Priority Short-Packet Covert Communication for UAV-Aided Relay Systems

In this paper, we investigate the timeliness of shortpacket covert communication assisted by unmanned aerial vehicle (UAV) relay. To evaluate the timeliness of short-packet covert communication, the covert age of information (CAol), which is the AoI subject to the covertness constraint, is adopted as a metric. Relied on this consideration, we formulate an optimization problem on the foundation of the expression for the average peak CAoI, to minimize the average peak CAoI by optimizing the UAV trajectory, the transmit power and the duration time of short-packet transmission. Particularly, to solve this optimization problem, we divide this problem into two subproblems with the result that the alternating solution strategy is devised with the successive convex approximation (SCA). At last, some representative numerical results are provided to demonstrate the efficiency and enhance the superiorities of our optimization method.