Securing Wireless Transmissions With RIS-Receiver Coordination: Passive Beamforming and Active Jamming

In this correspondence, we investigate the physical layer security issue with the assistance of a reconfigurable intelligent surface (RIS). In particular, we consider the single-input and multiple-output transmissions in the presence of a multi-antenna eavesdropper, where the legitimate receiver actively performs full-duplex jamming to confuse the eavesdropper. Meanwhile, the passive beamforming of the RIS is coordinated with the legitimate reception and jamming for security enhancement, leading to the joint optimization of receive beamforming, active jamming, and passive beamforming. The problem is solved under a block coordinate descent framework, where the receive beamforming is obtained through generalized eigenvalue decomposition, and the active jamming and passive beamforming are solved based on semidefinite programming. Simulation results show the combined effect of jamming and reflection upon the secrecy rate, also demonstrated is the performance superiority of the proposed scheme as compared with the conventional approaches in terms of wireless security.