Power allocation of random masked beamforming for guaranteed secure communications

In order to avoid eavesdropping, beamforming can be used not only to induce artificial noise or jamming signal to an eavesdropper, but also transmit desired signals to a legitimate user (or sensor) from an access point (AP) equipped with an antenna array. In this paper, with proper power allocation, we show that beamforming under a rich scattering environment can guarantee a certain secrecy rate with an overwhelming probability. This approach becomes attractive for slow fading channels where the ergodic secrecy rate cannot be used to decide a target secrecy rate.