Secure Transmission Design Based on the Geographical Location of Eavesdropper

In physical layer security, the geographical secure region as a practical security metric has received considerable interest. This paper derives the distribution functions of signal-to-interference-plus-noise ratios at Bob and Eve with Rician fading channels, which is used to calculate the secrecy outage probability for different Eve’s locations. Then, the secure region can be determined in geographical two-dimensional plane by comparing the secrecy outage probability with a threshold. Based on this, two optimization problems of the beamforming vector at Bob used for transmitting the artificial noise are constructed to expand the secure region, with and without the knowledge of Eve’s location, respectively. Simulation results are provided to depict the secure region with different antenna numbers, and illustrate that the secure region can be effectively expanded by using the optimized beamforming vector at Bob.