  We propose a novel artificial noise (AN) injection scheme for wireless
systems over quasi-static fading channels, in which a single-antenna
transmitter sends confidential messages to a half-duplex receiver in the
presence of an eavesdropper. Different from classical AN injection schemes,
which rely on a multi-antenna transmitter or external helpers, our proposed
scheme is applicable to the scenario where the legitimate transceivers are very
simple. We analyze the performance of the proposed scheme and optimize the
design of the transmission. Our results highlight that perfect secrecy is
always achievable by properly designing the AN injection scheme.
