Research On Physical Layer Security Enhancement Based On Smart Reflective Surface And Full-duplex Communicatio

Wireless energy-carrying transmission technology is considered to be one of the important means to solve the problem of energy shortage.This technology,together with beamforming technology and full duplex technology,can improve the physical layer security while improving the energy efficiency and performance of the system.Compared with half duplex technology,full duplex mode has obvious advantages in improving spectral efficiency,but the disadvantage is that full duplex mode has self-interference problem.The security of communication system has always been the focus of research in the field of communication.The use of beamforming technology can effectively improve the security of the system,and the phase of the signal can be adjusted to interfere with the eavesdropper’s eavesdropping signal.When receiving the signal,the receiver can send out interference signals in the full-duplex mode to interfere with the eavesdropper.In this paper,a multi-input multi-output communication system based on wireless energy-carrying transmission in full-duplex mode is proposed.On this basis,an intelligent reflector is added to improve the performance of the system,and the maximization of the reachability rate of the system is studied.Considering the channel uncertainty in the worst case,this paper studies a robust full-duplex(FD)secure transmission scheme for simultaneous wireless information and power transfer(SWIPT)in multi-input multi-output(MIMO)broadcasting systems.Most of the existing FD system robust communication designs only assume that the channel state information(CSI)related to the eavesdropper is imperfect,while this paper assumes that all channels are imperfect,which is more practical in reality.The worst-case model is used to model the channel uncertainty with bounded errors.Considering the suppression of loop interference,the objective of this paper is to jointly design the covariance matrix of power division rate,message bearing signal and interference signal to maximize the worst-case security rate achievable for the FD system under the constraint of the total transmitted power of the source node and the FD receiver node and the energy harvesting(EH)of the FD receiver node.The proposed optimization problem is highly non-convex.To solve this problem,we first introduce a proxy function to deal with the non-convexity in the objective function,and then decouple the optimization problem into two sets of subproblems,in which an S-Procedure is used to transform the worst-case constraints.Then,the two groups of subproblems are optimized alternately to obtain the local optimal solution.Simulation results demonstrate the effectiveness of the proposed robust FD scheme.In a full-duplex physical layer security system based on intelligent reflective surface technology,two nodes simultaneously send and receive signals in full-duplex mode in the presence of eavesdroppers.Setting up CSI related to eavesdropping channel is not perfect,both nodes and eavesdropper are equipped with multiple antennas.With intelligent reflector assistance,two nodes in full duplex mode,uplink and downlink can simultaneously send and receive signals,both working at the same frequency,thus improving the efficiency of the system.In order to solve the problem,the worst-case secrecy rate of the system is maximized through the joint design of intelligent reflector phase shift and sending precoding matrix,and the objective function of the solution is required to be highly non-convex.In order to solve this problem,this paper introduces a proxy function to transform the non-convex constraint in the objective function,and then decouples the problem to be solved into three subproblems,and uses S-program to deal with the semi-infinite constraint of channel uncertainty.The three subproblems are dealt with by alternate optimization algorithm,and the local optimal solution is finally obtained.In this paper,a penalty convex concave procedure(PCCP)is proposed for optimizing the phase shift matrix of intelligent reflective surfaces.In this method,relaxation variable is introduced to make it violate the non-convex unit modulus constraint,and the sum of violations is punished.When converging,the returned solution is the first order approximately optimal solution of the original solution sub-problem.The simulation results show that compared with the non-robust scheme,the robust scheme proposed in this paper has better performance.