Minimizing Average Age of Information in Reliable Covert Communication on Time-Varying Channels.

Covert communication in delay-sensitive application scenarios in the presence of an eavesdropper has drawn substantial attention in the context of data sensing and transmission. However, most of the existing works only focus on guaranteeing communication covertness, and information freshness by characterizing a recently new metric, termed as age of information (AoI), while they ignore the age of channel variation (AoC), which is the time duration that channel state information (CSI) is near-static, and important for reliable covert communication in dynamic environments. Depending on the packet length or dynamic environment, channel variation may occur faster than optimal AoI, and the power allocated to the users is not reliable to ensure covert communication. In this article, we propose a novel reliable covert communication scheme with the aim of minimizing AoI in the time-varying channels. We address two main challenges in time-varying networks: 1) transmitting users' packets with the requested desirable size; 2) guaranteeing reliable the negligible Eve's probability detection. In the simulation results, we show the performance and percentage of reliability of covert communication with the aim of minimizing AoI subject to a new constraint that guarantees the Eve's negligible detection probability compared to the existing schemes.