Covert Communication for Satellite Networks: Fundamentals, Applications, and Future Directions

Due to its global coverage and seamless connectivity, satellite communication is considered a promising research area for the upcoming 6G networks. However, due to the inherent openness of wireless communications and unique characteristics of satellite communication, satellite links are vulnerable to eavesdropping and other attacks by malicious devices. Fortunately, covert communication is emerging as a highly effective technique for improving the security of information transmission in satellite networks by exploiting environmental uncertainties to hide transmission signals. Thus, in this article, we explore the potential of covert communication to address the security challenges in satellite communication. We first introduce the characteristics of satellite communication and secure transmission techniques. Then, we present the basics of covert communications and discuss critical aspects of covert satellite communication. Next, we study covert satellite-terrestrial communication networks focusing on their covertness and reliability, taking into account the spatial variation of a satellite transmitter and the influence of terrestrial jamming nodes. Finally, several open research challenges in covert satellite communication are outlined.