Abstract:

A multiple antenna covert communication system is considered, which consists of a multi-antenna transmitter, a two-antenna legitimate user and a single-antenna eavesdropping user with power detection function. First, two transmission schemes based on maximum ratio transmission (MRT) and transmit antenna selection (TAS) are proposed respectively. In order to help to achieve covert communication between the transmitter and the legitimate user, the legitimate user working in full-duplex model also emits artificial noise (AN) to interfere with the eavesdropper’s detection. Then, based on the theoretical analysis of the system, the eavesdropper’s detection error probabilities, the system connection probabilities and covert throughputs under two schemes are derived respectively. Under the assumption of the eavesdropper’s optimal detection performance, its minimum detection error probabilities and the optimal detection thresholds under the two schemes are obtained, respectively. In addition, an optimization scheme is proposed, which can be used to obtain the maximum covert throughput of the system when the covert conditions are satisfied by optimizing the values of the transmission power of the artificial noise and the information transmission rate. The simulation results show that the proposed system can achieve covert communication, and the system has better performance when the transmitter adopts the TAS transmission scheme.

Key words: covert communication, artificial noise (AN), detection error probability, optimal detection threshold, covert throughput

摘要：

考虑一个多天线的隐蔽通信系统,该系统由一个多天线的发射机、一个双天线的合法用户和一个单天线且具有功率检测功能的窃听用户组成。首先,提出了两种分别基于最大比值传输（MRT）和发射天线选择（TAS）的隐蔽通信方案,为了帮助实现发射机和合法用户间的隐蔽通信,工作在全双工模式下的合法用户还会通过发射人工噪声（AN）来干扰窃听者的检测。其次,基于对系统的理论分析,分别推导了两种方案下窃听者的检测错误概率、系统的连接概率和隐蔽吞吐量。另外,在窃听者的检测性能最佳的假设下,分别得到了两种方案下窃听者的最小检测错误概率和最优检测门限值。除此之外,还提出了一种优化系统隐蔽性能的方案,该方案通过优化人工噪声发送功率和信息传输速率的值,可以得到满足隐蔽条件下系统的最大隐蔽吞吐量。最后通过仿真证明,所提系统可实现隐蔽通信,且当系统采用发射天线选择方案时,系统隐蔽性能更佳。

关键词: 隐蔽通信, 人工噪声（AN）, 检测错误概率, 最优检测门限值, 隐蔽吞吐量