With the development of sixth-generation (6G) wireless communication networks, the security challenges are becoming increasingly prominent, especially for mobile users (MUs). As a promising solution, physical layer security (PLS) technology leverages the inherent characteristics of wireless channels to provide security assurance. Particularly, stacked intelligent metasurface (SIM) directly manipulates electromagnetic waves through their multilayer structures, offering significant potential for enhancing PLS performance in an energy efficient manner. Thus, in this work, we investigate an SIM-assisted secure communication system for MUs under the threat of an eavesdropper, addressing practical challenges such as channel uncertainty in mobile environments, multiple MU interference, and residual hardware impairments. Consequently, we formulate a joint power and phase shift optimization problem (JPPSOP), aiming at maximizing the achievable secrecy rate (ASR) of all MUs. Given the non-convexity and dynamic nature of this optimization problem, we propose an enhanced proximal policy optimization algorithm with a bidirectional long short-term memory mechanism, an off-policy data utilization mechanism, and a policy feedback mechanism (PPO-BOP). Through these mechanisms, the proposed algorithm can effectively capture short-term channel fading and long-term MU mobility, improve sample utilization efficiency, and enhance exploration capabilities. Extensive simulation results demonstrate that PPO-BOP significantly outperforms benchmark strategies and other deep reinforcement learning algorithms in terms of ASR.10.1109/TWC.2026.3658332
Low-Complexity Multi-Agent Continual Learning for Stacked Intelligent Metasurface-Assisted Secure Communications
Beijing Jiaotong University（北京交通大学）；Nanjing Rongcai Transportation Technology Research Institute Co., Ltd.（南京荣彩交通技术研究院有限公司）；University of New South Wales（新南威尔士大学）；Nanyang Technological University（南洋理工大学）
STAR-RIS-Assisted Integrated Sensing, Secure Communication, and Power Transfer: A Transmit Power Minimization Framework
South China University of Technology（华南理工大学）；New York University Abu Dhabi（纽约大学阿布扎比分校）；NYU Tandon School of Engineering（纽约大学坦顿工程学院）；Jinan University（暨南大学）
RIS-Assisted Secure Transmission with Artificial Noise: Element Allocation and Measurements
Communications and Signal Processing Research (HISAR) Lab., TUBITAK BILGEM, Kocaeli, Turkiye（土耳其科贾埃利 TÜBİTAK BILGEM 通信与信号处理研究（HISAR）实验室）；Department of Electrical and Computer Engineering, School of Engineering and Digital Sciences, Nazarbayev University, Astana, Kazakhstan（哈萨克斯坦阿斯塔纳 纳扎尔巴耶夫大学工程与数字科学学院电气与计算机工程系）
Discrete Antenna Positioning and Beamforming Design for RIS-Assisted MA Secure ISAC Systems
Xi’an Jiaotong University（西安交通大学）；Stevens Institute of Technology（史蒂文斯理工学院）；Southeast University（东南大学）；Tongji University（同济大学）；Beijing University of Posts and Telecommunications（北京邮电大学）；Shanghai Jiao Tong University（上海交通大学）
Tertiary-Mode STAR-RIS for Secure NOMA: Integrating Transmission, Reflection, and Jamming
Indian Institute of Technology Guwahati（印度果阿哈提印度理工学院）；Indian Institute of Technology (BHU) Varanasi（印度瓦拉纳西印度理工学院（贝拿勒斯））；San Diego State University（圣地亚哥州立大学）
Intelligent Joint Security and Delay Determinacy Performance Guarantee Strategy in RIS-Assisted IIoT Communication Systems
State Key Laboratory of Networking and Switching Technology, BUPT（网络与交换技术国家重点实验室，北京邮电大学）；College of Electronics and Information Engineering, Beibu Gulf University（北部湾大学电子信息工程学院）；Department of Broadband Communication, Peng Cheng Laboratory（鹏城实验室宽带通信系）；National School of Elite Engineering, University of Science and Technology Beijing（北京科技大学高等工程师学院）
Secrecy Rate Maximization in RIS-Assisted MIMO Systems Using a Practical Hardware Model
Indian Institute of Technology, Bombay（印度孟买理工学院）；Institut Teknologi Sepuluh Nopember（印尼十十一月理工学院）；Indian Institute of Technology (Indian School of Mines), Dhanbad（印度多汉巴德印度理工学院（印度矿业学院））；National Sun Yat-sen University（国立中山大学）
Joint Hybrid Beamforming and Artificial Noise Design for Secure Multi-UAV ISAC Networks
School of Information（信息学院）；Navigation Air Force Engineering University（导航空军工程大学）；School of Air Defense（防空学院）；Antimissile Air Force Engineering University（防空导弹空军工程大学）；Sixty-Third Research Institute（第六十三研究所）；National University of Defense Technology（国防科学技术大学）；School of Air Traffic Control（空管学院）；Nav. Air Force Engineering University（导航空军工程大学）
Secure mmWave Beamforming with Proactive-ISAC Defense Against Beam-Stealing Attacks
Electrical and Computer Engineering Department, Worcester Polytechnic Institute, USA（沃斯特理工学院电子与计算机工程系）；Electrical and Computer Engineering Department, Mississippi State University, USA（密苏里州立大学电子与计算机工程系）
