Physical Layer Security And Legitimate Surveillance Techniques Based On Active Eavesdropping

The rapid development and increasing popularity of wireless communication technology has a tremendous impact on human production and daily life.Wireless networks have become an indispensable component of people's life.With the rapid growth of data traffic in wireless communication systems and the emergence of diversified and differential communication services,wireless security is facing a serious threat.On the one hand,wireless services such as mobile payment and online banking are becoming more and more popular.Compared with wired communication,the openness and inherent broadcast nature of wireless media make wireless communication vulnerable to eavesdropping and security attacks by malicious users.Therefore,providing secure and reliable wireless connections has become the key demand for future wireless networks.On the other hand,the convenience of wireless communication services make it easy for criminals or malicious users to exploit and engage in criminal activities such as terrorist attacks,thereby endangering national security.Hence,deploying powerful surveillance measures on suspicious communications has become an important guarantee to protect public security.Based on the above challenges,this paper provides a detailed research on the physical layer security transmission systems and the legitimate surveillance systems.Aiming at the legitimate surveillance problem in wireless communication systems,the active monitoring mechanism of full-duplex relay cooperation is studied.Aiming at the problem of physical layer security transmission in the system with active eavesdropping,a source beamforming optimization algorithm is designed to combat active eavesdropping.The main research contents and innovations in this paper can be summarized as follows.1)The relay cooperative active monitoring scheme in the legitimate surveillance system is investigated,which can minimize the suspicious rate of suspicious communication users while ensuring legitimate surveillance performance.Considering that the relay works in full-duplex(FD)mode,it forms a cooperative relationship with the monitor.The relay sends suspicious information to the monitor while transmitting the jamming signal to the suspicious receiver.In order to reduce the security threats brought by suspicious users and ensure the legitimate surveillance performance,the relay beamforming and power allocation scheme are jointly designed.Based on the theoretical derivation,the closed expression for the beamforming vectors are derived and the optimal relay power and jamming power are obtained.Finally,the simulation results show that compared with the traditional legitimate surveillance scheme,the proposed novel relay cooperative active surveillance scheme can significantly improve the monitoring performance and suppress suspicious communication.2)The physical layer security mechanism in wireless communication systems is investigated.Eavesdropping strategies is designed for eavesdroppers to improve their eavesdropping performance,including node selection,beamforming design,and power allocation,are considered to minimize system secrecy rate.In order to combat active eavesdropping,a source beamforming vector optimization algorithm based on the worst case is proposed to maximizing the system secrecy rate.By solving the generalized eigenvector problem and iterative optimization,the optimal source beamforming vector is obtained.Finally,the convergence and effectiveness of the proposed optimization algorithm are studied and verified by simulation results.The algorithm can converge quickly and significantly improve the secrecy rate.