Jamming Assisted Covert Communication Improved by A Store-enabled Relay

In this paper, we investigate the jamming-assisted covert communication in wireless relay networks. For the first time, we propose a new covert communication scheme with a store-enabled relay, who stores the received private information and then forwards it when the channel gain to the destination is larger than a preset value named forwarding threshold. For the proposed scheme, we characterize the storage state at relay by exploiting the classical birth-and-death process, and derive the steady state distribution. Then, the prior transmission probability at relay, and the average covertness constraint by considering a worst-case scenario are derived. Furthermore, the average packet error probabilities from source to relay, and from relay to destination are also derived to reveal the impacts of forwarding threshold on the communication reliability. In addition, effective covert rate (ECR) is adopted to jointly reveal the pros-and-cons impacts of forwarding threshold on the communication covertness, reliability and efficiency. Finally, simulation results are provided to verify the superiority of proposed scheme by comparing to the traditional relay scheme without storage capacity.