This paper investigates the covert communications via cooperative jamming and relay selection in a wireless relay system, where a source intends to transmit a message to its destination with the help of a selected relay, and a warden attempts to detect the existence of wireless transmissions from both the source and relay, while friendly jammers send jamming signals to prevent warden from detecting the transmission process. To this end, we first propose two relay selection schemes, namely random relay selection (RRS) and max-min relay selection (MMRS), as well as their corresponding cooperative jamming (CJ) schemes for ensuring covertness in the system. We then provide theoretical modeling for the covert rate performance under each relay selection scheme and its CJ scheme and further explore the optimal transmit power controls of both the source and relay for covert rate maximization. Finally, extensive simulation/numerical results are presented to validate our theoretical models and also to illustrate the covert rate performance of the relay system under cooperative jamming and relay selection.

翻译：本文研究了无线中继系统中通过合作干扰与中继选择实现的隐蔽通信，其中信源借助选定的中继向目的地传输消息，而监测者试图检测来自信源和中继的无线传输是否存在，同时友好干扰机发送干扰信号以阻止监测者检测传输过程。为此，我们首先提出两种中继选择方案，即随机中继选择（RRS）和最大最小中继选择（MMRS），以及它们对应的合作干扰（CJ）方案，以确保系统的隐蔽性。随后，我们为每种中继选择方案及其合作干扰方案下的隐蔽率性能建立理论模型，并进一步探索信源与中继的最优发射功率控制以实现隐蔽率最大化。最后，通过大量仿真/数值结果验证了我们的理论模型，并展示了合作干扰与中继选择下中继系统的隐蔽率性能。