  This paper consider a new secure communication scene where a full-duplex
transmitter (Alan) need to transmit confidential information to a half-duplex
receiver (Bob), with a silent eavesdropper (Eve) that tries to eavesdrop the
confidential information. For realizing secure communication between Alan and
Bob, a novel two phases communication scheme is proposed: in Phase 1, Alan and
Bob send artificial noises (AN) simultaneously, while in Phase 2, Alan
superimposes the AN received in Phase 1 with its confidential signal and sends
the mixed signalto Bob. Since the mixed AN could degrade the SINR (Signal to
Interference and Noise Ratio) of Eve, but does not affect the SINR of Bob, a
secrecy capacity can be achieved. We also derive the conditions that the
secrecy capacity of the proposed scheme exists, and analyze the secrecy outage
probability under Rayleigh fading channel. Numerical results show that the
secrecy capacity is about two times higher than without AN, even though in the
proposed scheme half of the time is used to transmit ANs, and the outage
probability is about five times lower than that without AN.
