# Covert Communication for Integrated Satellite-Terrestrial Relay Networks with Cooperative Jamming
## 5 Conclusions  
As shown in Table 3, we compare this article with some current research on covert communication and briefly summarize its innovations. Furthermore, the main work and contribution are elaborated as follows. In this article, we primarily studied the covert performance in ISTRN with cooperative jamming. Primarily, we proposed a specific system model of covert communication, which was based on ISTRN. Our work aimed to maximize the effective covert rate under a covertness constraint. To improve the system's effectiveness, a relay cooperative scheme was presented. Based on this, the probability of detection error at the eavesdropper and the outage probability of legitimate communication were obtained to quantify the system's covert performance.  
Further, in order to explore the impacts of transmission power and jamming power on covert communication and to enhance the covert performance, a power optimization algorithm was presented. Through the numerical simulation results, it was clear that, as the transmission power increased and the jamming power decreased, the probability of detection error declined continuously as the legitimate communication signal was more easily detected by the eavesdropper, which suffered less interference at the same time--namely, its detection became more accurate.  
Moreover, as the transmission power rose, there was a gain in the effective covert rate. However, in order to meet the covertness, higher jamming power was also required, which brought heavy interference to the legitimate communication. Based on this, we designed the power allocation factor and found that an optimal power allocation factor, which effectively balanced the information and jamming power, could be obtained to achieve system covertness. Lastly, the numerical simulation results also implied that a higher covert rate was allowed when the covertness requirement was weakened.  
[PERSON], [PERSON] and [PERSON] conceived and designed the experiments; [PERSON] performed the experiments; [PERSON] analyzed the data; [PERSON] contributed analysis tools; and [PERSON] wrote the paper. All authors have read and agreed to the published version of the manuscript.  
This work was supported by the National Science Foundation of China under Grants 62001517, 61901502 and 61971474 and by the National Postdoctoral Program for Innovative Talents under Grant BX20200101.  
**Data Availability Statement:** Not applicable.  
**Conflicts of Interest:** The authors declare no conflict of interest.  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Reference Number** & **Main Feature or Contribution** \\ \hline
[21] & Enhancing terrestrial covert communication with an uninformed jammer \\ \hline
[22] & Achieving terrestrial covert communication with the aid of inherent uncertainty of channels \\ \hline
[23] & Achieving terrestrial covert communication in an AF relay network \\ \hline
[24] & Proposing an optimization strategy for the terrestrial covert system capacity \\ \hline
[25] & Using a full-duplex receiver as the jammer to enhance covertness \\ \hline
[29] & UAV-based air terrestrial covert communication \\ \hline Our article & Satellite–terrestrial covert communication by relay-aided jamming \\ \hline \hline \end{tabular}
\end{table}
Table 3: Comparative analysis with the current research on covert communication.