Covert Communication With Time Uncertainty in Time-Critical Wireless Networks

In this work, we investigate the status packet covert communication with time uncertainty in time-critical wireless networks. We model the packet generation as a Poisson process that concatenates the information timeliness and communication covertness, since the prior transmission probability is highly correlated with the packet generation. To balance between the timeliness and covertness of the status packet transmission, we propose two schemes, named random sub-slot selection (RSS) scheme and random channel use selection (RCUS) scheme, by exploiting the random transmission time to confuse a warden Willie’s binary detection on the covert communication. Subsequently, the average age of information (AoI) subject to the covertness constraint is derived for the proposed RSS and RCUS schemes. It is demonstrated that the symbol-length of the status packet introduces a non-trivial tradeoff between the covertness and timeliness. Inspired by this, further designs of the symbol-length and the transmit power for the proposed two schemes are formulated as optimization problems and solved optimally. Our numerical results demonstrate the superiority of proposed schemes over the existing covert communication strategies. In addition, our examination reveals that the RCUS scheme outperforms the RSS scheme when the covertness constraint is extremely strict. Otherwise, the RSS scheme generally outperforms the RCUS scheme in terms of achieving a lower AoI.