Effective eavesdropping in the Artificial noise aided security scheme

The Artificial noise (AN) injection scheme is recently proposed to secure wireless transmissions. By simultaneously transmitting data symbols and artificial interference, it prevents the eavesdropper from decoding the secret message intended for the legitimate receiver. In this paper, we mainly focus on weakness of the AN security scheme. First, we analyze the necessary condition for such a scheme to guarantee that the legitimate transmitter-receiver pair can achieve a positive secrecy communication rate. And then, we further propose an effective eavesdropping strategy to counteract such a security scheme once the condition does not hold up in some wireless systems. Our proposed wiretap method involves complex-valued independent component analysis (ICA) and requires the antenna number of the eavesdropper's is larger or equal to that of the transmitter's. Simulation results demonstrate the effectiveness of this wiretap method.