Physical layer security (PLS) technologies are expected to play an important role in the next-generation wireless networks, by providing secure communication to protect critical and sensitive information from illegitimate devices. In this paper, we propose a novel secure communication scheme where the legitimate receiver use full-duplex (FD) technology to transmit jamming signals with the assistance of simultaneous transmitting and reflecting reconfigurable intelligent surface (STARRIS) which can operate under the energy splitting (ES) model and the mode switching (MS) model, to interfere with the undesired reception by the eavesdropper. We aim to maximize the secrecy capacity by jointly optimizing the FD beamforming vectors, amplitudes and phase shift coefficients for the ESRIS, and mode selection and phase shift coefficients for the MS-RIS. With above optimization, the proposed scheme can concentrate the jamming signals on the eavesdropper while simultaneously eliminating the self-interference (SI) in the desired receiver. To tackle the coupling effect of multiple variables, we propose an alternating optimization algorithm to solve the problem iteratively. Furthermore, we handle the non-convexity of the problem by the the successive convex approximation (SCA) scheme for the beamforming optimizations, amplitudes and phase shifts optimizations for the ES-RIS, as well as the phase shifts optimizations for the MS-RIS. In addition, we adopt a semi-definite relaxation (SDR) and Gaussian randomization process to overcome the difficulty introduced by the binary nature of mode optimization of the MS-RIS. Simulation results validate the performance of our proposed schemes as well as the efficacy of adapting both two types of STAR-RISs in enhancing secure communications when compared to the traditional selfinterference cancellation technology.

翻译：物理层安全（PLS）技术预计将在下一代无线网络中发挥重要作用，通过提供安全通信来保护关键敏感信息免受非法设备的窃取。本文提出一种新型安全通信方案，其中合法接收机采用全双工（FD）技术，在同时透射和反射可重构智能表面（STAR-RIS）的辅助下发射干扰信号。该表面可在能量分裂（ES）模型和模式切换（MS）模型下工作，从而干扰窃听者的非法接收。我们旨在通过联合优化FD波束成形向量、ES-RIS的幅度和相移系数，以及MS-RIS的模式选择和相移系数，最大化保密容量。通过上述优化，所提方案可将干扰信号集中于窃听者，同时消除合法接收机处的自干扰（SI）。为处理多变量的耦合效应，我们提出一种交替优化算法迭代求解问题。进一步地，我们采用逐次凸近似（SCA）方案处理波束成形优化、ES-RIS的幅度与相移优化，以及MS-RIS相移优化中存在的非凸性。此外，针对MS-RIS模式优化中二进制变量引入的求解困难，我们采用半定松弛（SDR）和高斯随机化过程。仿真结果验证了所提方案的性能，并表明与传统自干扰消除技术相比，适配两种STAR-RIS均能有效增强安全通信。