Energy-Efficient Covert Wireless Communication Through Probabilistic Jamming

In this letter, we propose a novel energy-efficient covert wireless communication scheme through probabilistic jamming, where a jammer probabilistically transmits artificial noise (AN) with variable power against a warden's detection. For the proposed scheme, the closed-form expressions for the warden's detection error probability, the transmission outage probability, and the system energy efficiency are derived to reveal the impacts of the prior AN transmission probability on communication covertness, reliability, and system energy efficiency. To further improve the system energy efficiency, an optimization problem is formulated to determine the optimal prior AN transmission probability and the optimal transmit power of private information subject to a covertness constraint, which shows that continuous jamming is generally not optimal to maximize the energy efficiency in covert communication systems. Simulation results verify our analysis and show the superiority of proposed scheme comparing to a widely adopted scheme where the jammer always transmits AN with random transmit power.