Joint Beamforming and Artificial Noise Design in Wireless Downlink Networks

Abstract:
This paper investigates a wireless downlink communication system with multiple single-antenna eavesdroppers by utilizing artificial noise, which is different from most existing works that allocate the artificial noise to the zero space of the legitimate channel. Assuming that the transmitter perfectly knows the ideal channel state information, an optimal scheme of joint beamforming and artificial noise design is proposed. Under the conditions of ensuring the receiving SNR threshold of legitimate users and limiting the receiving SNR of eavesdroppers, this paper focus on transmit power minimization problem. Although the proposed optimization problem is nonconvex, it can be converted into a convex problem by using semidefinite program (SDP) relaxation method and solved effectively. The transmit power allocation between private signals and artificial noise is solved, and both the reduced system energy consumption information transmission safety are achieved. Simulation results show that the joint optimization scheme consumes less transmit power than the scheme without artificial noise on the premise of meeting the system safety performance.