Antenna switching for security enhancement in full-duplex wiretap channels

We propose an antenna switching scheme in the full-duplex wiretap channel where the legitimate receiver, equipped with two antennas, operates in a full-duplex mode. We focus on a practical eavesdropping scenario where the instantaneous channel state information of the eavesdropper's channel is not available at the transmitter and the receiver. In our proposed scheme, the receiver selects the antenna that maximizes the main channel gain as the receive antenna and uses the remaining antenna to transmit jamming signals. We derive an exact expression for the secrecy outage probability to evaluate the secrecy performance of our new scheme. This expression allows us to quantify the secrecy performance gain of our proposed scheme relative to a standard antenna predetermination scheme where the receive and transmit antennas at the receiver are predetermined. We demonstrate that our scheme achieves a lower secrecy outage probability than the antenna predetermination scheme. We also show that our scheme achieves the full secrecy diversity order whereas the antenna predetermination scheme does not.