Research On Key Technologies Of Physical Layer Security Assisted By Reconfigurable Intelligent Surface

This project studies the key technology of physical layer security assisted by reconfigurable intelligent surface(RIS).As a new technology,RIS plays an important role in physical layer security research because of its low complexity,low energy consumption and full duplex without self-interference.Therefore,in order to solve the problem of eavesdropper when legitimate user receives information,the scenarios of single user,single eavesdropper and channel state information known,single user,multi-eavesdropper and channel state information unknown are considered.Through RIS assisted cooperative interference relay,artificial noise and power allocation methods,combined with beamforming technology,multiple RISs selection scheme are designed at the same time in order to improve the energy efficiency and reduce the signal to interference noise ratio(SINR)of eavesdroppers.The purpose of improving the confidentiality is achieved,and finally the secure communication is realized.At the same time,the complexity of the algorithms is calculated and analyzed,and the effectiveness of the proposed scheme is verified by simulation.Firstly,aiming at the situation that there is a single antenna eavesdropper in the link between the base station and the user,the physical layer security system model of RIS assisted cooperative interference is reasonably built.In order to minimize the SINR of the eavesdropper,the cooperative optimization of the base station and RIS beamforming scheme is designed through the scheme that the RIS reflects the interference signal to interfere with the single antenna eavesdropper.At the same time,the relationship between the number of RIS components and the SINR at eve,the base station transmit power and the SINR at Eve are simulated to verify the effect of the design scheme on improving the security performance of the system.Secondly,considering the scenario of multiple RISs auxiliary communication,aiming at the problem of excessive energy loss in this scenario,a RIS selection scheme based on the maximum received signal-to-noise ratio(SNR)is designed to ensure the optimal confidentiality and energy efficiency from the perspective of improving energy efficiency.The influence of the number of RIS components,the distance between RIS and user on the received signal quality is simulated,and the effectiveness of the designed RIS selection scheme is verified.Then,a system model is established for the scenario that there are multiple single antenna eavesdroppers in the base station to user link.The base station equipped with multiple antennas is considered as the transmitter to send confidential information to a single antenna user on the ground.The base station sends artificial noise and performs beamforming.At the same time,the signal reflected by RIS is configured to interfere with the single antenna eavesdroppers and improve the security performance.Also,the power allocation scheme of cooperative optimization of RIS beamforming and artificial noise at base station is designed,and the relevant parameters are simulated to verify the performance of the scheme.Finally,through the analysis of the simulation results,it is concluded that the physical layer security performance of the communication system can be improved by adding RIS combined with beamforming,cooperative interference,artificial noise and power allocation technology.At the same time,when multiple RISs assist communication,reasonable RIS selection can further improve the energy efficiency of the system on the premise of ensuring the system security.