Joint Packet Generation and Covert Communication in Delay-Intolerant Status Update Systems

Abstract

In this letter, we jointly investigate packet generation and covert communication in delay-intolerant status update systems. For the first time, we establish a bridge between the prior transmission probability and the finite block-length in covert communication by modeling the stochastic status packet generation as a Poisson process. Considering a general prior transmission probability model, we derive closed-form expressions for the covertness constraint, the average packet error probability, and the effective covert throughput (ECT) to reveal the non-trivial tradeoff between the communication covertness and reliability. An optimization problem to maximize ECT is also formulated, and then the optimal transmit power and block-length are obtained, respectively. In contrast to exiting results, our examination shows that the longest block-length and the widely adopted equal prior probabilities are generally suboptimal when jointly considering the packet generation and covert communication.