论文标题
混合继电器反射智能表面辅助秘密通信
Hybrid Relay-Reflecting Intelligent Surface-Aided Covert Communications
论文作者
论文摘要
在本文中，我们建议使用混合继电器反射智能表面（HR-RIS）来增强秘密通信系统的性能。具体而言，HR-RIS由被动反射元素和主动继电器元素组成，以操纵从发射机到所需的接收器的无线信号，同时通过避免避免守望者检测到的此类信号来确保传输的隐秘性。为了充分探索HR-RIS所提供的好处，我们首先制定了HR-RIS的发射功率和继电器/反射系数的关节设计，作为优化问题，以最大化秘密速率受到掩盖的约束。为了解决此优化问题的解决方案，我们将在秘密速率上获得上限的封闭形式表达式，基于该算法，我们开发了一种替代算法来解决公式的优化问题。我们的检查表明，HR-RIS在达到较高的秘密率方面表现出色。有趣的是，我们还可以观察到HR-RI带来的绩效增益的主要部分可以通过少数活跃的继电器元素（例如5）获得，并且进一步增加了这一数字并不能改善秘密沟通性能。
In this paper, we propose to use a hybrid relay-reflecting intelligent surface (HR-RIS) to enhance the performance of a covert communication system. Specifically, the HR-RIS consists of passive reflecting elements and active relay elements to manipulate the wireless signals from a transmitter to a desired receiver while ensuring the covertness of the transmission via avoiding such signals being detected by a warden. To fully explore the benefits offered by the HR-RIS, we first formulate the joint design of the transmit power and relay/reflection coefficients of the HR-RIS as an optimization problem to maximize the covert rate subject to a covertness constraint. To tackle the solution to this optimization problem, we then derive a closed-form expression for an upper bound on covert rate, based on which we develop an alternate algorithm to solve the formulated optimization problem. Our examination shows that the HR-RIS outperforms the traditional RIS in term of achieving a higher covert rate. Interestingly, we also observe the major part of the performance gain brought by the HR-RIS can be obtained by a small number of active relay elements (e.g., 5) and further increasing this number does not improve the covert communication performance.
