Covert Communication with Relay Selection based on Outdated CSI

In this paper, we study the comprehensive effect of outdated channel state information (CSI) on the performance of covert communication in a relay network with relay selection. We will examine the scenario in which the selected relay secretly transmits its own message to the destination while forwarding the source’s message. We first derive the calculation formulas of detection error probability (DEP) and average covert rate (ACR) respectively, and then reveal the influence of different system parameters on the performance of the covert communication system through theoretical analysis. Our analysis indicates that the outdated CSI causes an increase in DEP, which can facilitate the covert communication. Applying relay selection can also cause an increase in DEP when the correlation coefficient is low. With the increase of the fixed rate of the source, the application of relay selection can increase the ACR.