Secure Wireless Communication With Artifical Noise In Multi-user And Multi-eavesdropper Scenarios

Because of the broadcast nature of wireless communication, the wireless commu-nication system is lack of secure physical boundary. Therefore such systems is openfor the potential eavesdropper and secure wireless communication is then becominga key problem of physical layer. Secure wireless communication in the Multi-userand Multi-eavesdropper (MUME) scenario is considered in this paper, where there isone transmitter, some legitimate user (receivers) and some eavesdroppers. The securetransmission can usually be improved when the transmitter simultaneously transmitsinformation-bearing signal to the intended receivers and artificial noise to confuse theeavesdroppers.There inevitably is some co-channel interference (CCI) in the multi-user commu-nication systems, and several processing schemes have been proposed to limit CCI:SVD method, Zero-Forcing (ZF) beamforming method and Block Diagonalization(BD) method. However, according to the early studying, the SVD method and the ZFbeamforming method are simple but of little ideal performance. While the BD methodis of ideal performance but too complex. In view of the strong and weak points of theprevious schemes, we propose an alternative approach, which is based on maximizingthe signal-to-leakage ratio (SLR) and is named SLR mathod. The second alterna-tive approach is based on so-called dirty-paper coding (DPC) and ZF beamforming.By means of known interference pre-cancelation at the transmitter, each precoder isdesigned according to the previously designed precoding matrices, rather than otherusers’ channels, which in return provides extra Secrecy Degree of Freedom (SDF) forthe design of precoders. Therefore, we just name it ISDF (Increasing Secrecy Degreeof Freedom) method in brief.In all schemes, the information-bearing signal is transmitted with just enough power to guarantee the desired Quality-of-Service (QoS) at the desired receivers, whilethe remainder of the power is used to broadcast artificial noise that selectively degradesthe passive eavesdropper’s signal. Simulations demonstrate that the proposed SLRmethod can achieve a compromise between the secrecy performance and complexity,while the ISDF method achieves the best performance and relatively low complexitycompared with the existing best approach—BD method.