Abstract: A strategy was studied which takes the advantage of artificial noise to improve the performance of legitimate user for physical layer security transmission systems using beamforming technology and artificial noise. Based on transmitted symbols and channel coefficients, the transmitter determines whether or not part of artificial noises are beneficial to the signal detection at the legitimate receiver. It divides the original artificial noises into two parts:constructive noises and common noises, then it designs beamforming vectors accordingly. By exploiting the constructive noises, the signal-to-noise ratio at the legitimate receiver is improved while that at the illegal receiver will remain the same. The bit error rate and the secrecy capacity are analyzed and simulated when phase shift keying modulation is used. It is demonstrated that the proposed scheme can improve the performance of the legal receiver and enhance secrecy capacity.

Key words: physical layer security, artificial noise, bit error rate, secrecy capacity, phase shift keying