电子学报2025，Vol.53Issue(11)：3932-3942,11.DOI:10.12263/DZXB.20250532
EL-RIS赋能的混合多播-单播隐蔽通信
EL-RIS Empowered Multicast-Unicast Covert Communication
摘要
Abstract
This paper proposes an extremely large-scale reconfigurable intelligent surface(EL-RIS)-empowered hy-brid multicast-unicast covert communication system to overcome the"double-fading"effect and energy leakage issues in conventional RIS-assisted systems.By leveraging its massive array scale,the EL-RIS significantly expands the near-field re-gion.This expansion not only enhances the user channel gain but also introduces a distance-degree of freedom for covert communication,thereby substantially reducing the signal energy leakage to the eavesdropper.The multicast signal is used to broadcast public information to multiple users,with its transmit power following a uniform distribution,creating power un-certainty,while the unicast signal carries the users'covert information.The multicast signal can provide a"cover"for the covert transmission of the unicast signal,confusing the eavesdropper's detection and effectively improving the covert rate.Energy focusing is achieved at the user locations via EL-RIS,while energy leakage at the eavesdropper is suppressed.To maximize the system's performance,we formulate a non-convex optimization problem that jointly designs the base station beamforming and the EL-RIS reflection coefficients.Aiming to maximize the users'covert sum rate under the constraints of covertness and successful multicast signal decoding.An efficient alternating optimization(AO)algorithm is proposed,which decouples the original problem into two subproblems base station beamforming optimization and EL-RIS reflection coefficient optimization.The weighted minimum mean square error(WMMSE)algorithm is employed to reformulate the objective function,transforming the non-convex constraints into second-order cone(SOC)forms,and further representing them as linear matrix inequalities(LMI),thereby reducing the complexity of the optimization problem.For the design of EL-RIS reflection coefficients,the unit-modulus constraints render the problem non-convex and computationally challenging.To address this,a low-complexity algorithm based on the alternating direction method of multipliers(ADMM)is proposed.By introducing auxiliary variables,the original problem is decoupled.Subsequently,an augmented Lagrangian function is constructed to decompose the problem into multiple tractable subproblems,thereby enhancing the algorithm's computation-al efficiency.Simulation results demonstrate that the proposed scheme significantly outperforms benchmark schemes in terms of covert communication rate,unicast signal energy can achieve focusing at the user locations.Under the near-field channel model,the beam focusing realized by EL-RIS improves the covert sum rate by 57%compared to the far-field mod-el.Increasing the number of EL-RIS units can further extend the near-field region,enhance the beam focusing effect,and improve the communication system's robustness against changes in the eavesdropper's location.Even in extreme eavesdrop-ping scenarios,the system can maintain a high covert communication rate.关键词
隐蔽通信/超大规模智能超表面/混合多播-单播传输/近场通信/加权最小均方误差Key words
covert communication/extremely large-scale reconfigure intelligent surface/hybrid multicast-unicast transmission/near field communication/weight minimum mean square error分类
信息技术与安全科学引用本文复制引用
吕璐,梁啟辉,冯云鹏,杨龙,管新荣..EL-RIS赋能的混合多播-单播隐蔽通信[J].电子学报,2025,53(11):3932-3942,11.基金项目
国家自然科学基金(No.62271368,No.62171461) （No.62271368,No.62171461）
中央高校基本科研业务费(No.QTZX23066) （No.QTZX23066）
陕西省创新能力支撑计划(No.2024RS-CXTD-01) （No.2024RS-CXTD-01）
陕西省重点研发计划(No.2023-ZDLGY-50) National Natural Science Foundation of China(No.62271368,No.62171461) （No.2023-ZDLGY-50）
Fundamental Re-search Funds for the Central Universities(No.QTZX23066) （No.QTZX23066）
Shaanxi Innovation Capability Support Program(No.2024RS-CXTD-01) （No.2024RS-CXTD-01）
Key Research and Development Program of Shaanxi Province(No.2023-ZDLGY-50) （No.2023-ZDLGY-50）
