| Summary: | 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.
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