Research On Physical Layer Security Transmission Protocol Based On Beamforming And Spatial Modulation

The transmission and acquisition of information has become easier and faster because of rapidly evolving wireless technology.This will cause some problems of leaking information.So,it is very important for realizing secure communication in applications.For wireless communication systems,the difference of channel physical properties between legitimate receivers and eavesdroppers may be used to achieve secure communication.The corresponding physical layer security has become an interesting method for secure communication.In this thesis,we investigate the multi-user multi-eavesdropper scenario and study the data secure transmission scheme in the physical layer.For a communication network with multi-user cooperative relays,a physical layer secure transmission scheme is proposed with respect to the minimized transmission power.There are two communication network models for Multiple-Input Single-Output,based on interference relaying assistance.In both models,the relay sends artificial noise which will be used to reduce the signal-to-noise ratio for the eavesdropping.Meanwhile,the beamforming techniques is applied to further improve the signal quality for the receiver.When the channel state information of both the main and eavesdropping channels are imperfect,the robustness of the transmission scheme can be enhanced.The simulation experiments show that the transmission scheme can efficiently reduce the transmission power while it ensures the security.For a multi-user Multiple-Input Multiple-Output(MIMO)system,a secure transmission scheme is proposed by using random precoding.Based on generalized precoding assisted spatial modulation,multiple antennas are activated and carry different information to increase the transmission rate.Here,the precoding is divided into three parts:to eliminate the inter-user interference,ensure the activation of user specific antennas,and introduce random interference,reduce the signal quality of the eavesdropping channel in order to enhance the security for the receiver side.In addition,in order to further improve the channel quality of the main channel,an antenna selection algorithm is proposed.This can increase the difference between the main and the eavesdropping channel qualities.The simulation results show that the proposed scheme can against the eavesdropping while it ensures the performance for legitimate receivers.