Improving Physical Layer Security for MISO Systems via Using Artificial Noise

Physical layer security approaches enable secure message transmission without upper layer data encryption and thus draw intensive attention recently years. Following this topic, this paper proposes a novel approach to improve the security of multiple-input single-output (MISO) communications links in the presence of non-colluding passive Poisson distributed eavesdroppers. In the proposed approach, it is assumed that the channel state information (CSI) of the main channel is known and that of the eavesdropper channel is unknown. Through beamforming vectors, the transmitter transmits information signal to the legitimate receiver along with artificial noise (AN) to confuse the eavesdroppers. Secrecy outage probability (SOP) is adopted to describe the secrecy performance, and based on it, security region (SR) is used from the perspective of space to illustrate the security. In obtaining the SOP of the described transmission link, stochastic geometry theory is adopted. It is shown that the stochastic geometry theory provides a powerful tool in obtaining a solution of SOP. Furthermore, the secrecy performance between transmitting approaches with AN and without AN is compared. The SR is plotted and the factors impacting security are analyzed accordingly.