论文标题
可重新配置的智能表面辅助秘密密钥一代在空间相关的频道中
Reconfigurable Intelligent Surface-Assisted Secret Key Generation in Spatially Correlated Channels
论文作者
论文摘要
可重新配置的智能表面（RIS）是一项破坏性技术，旨在提高物理层密钥生成（PKG）的性能，这要归功于其智能自定义无线电环境的能力。现有的RIS辅助PKG方法主要基于基站（BS）和RIS的独立和相同分布（I.I.D.）通道模型的理想主义假设。但是，I.I.D.在各向同性散射环境中典型的RI不准确，并且忽略了通道空间相关的存在可能会降低PKG性能。在本文中，我们建立了一个通用的空间相关通道模型，并根据发射和反射光束成形提出了一个新的通道探测框架。我们得出了封闭形式的密钥生成率（KGR）表达式，并提出了优化问题，该问题可以通过使用Mirror-Prox方法使用低复合块连续的上限最小化（BSUM）来解决。仿真结果表明，与基于I.I.D.的现有方法相比。褪色模型，当两个相邻的RIS元素之间的间距是波长的四分之一时，我们提出的方法可实现大约5美元DB传输功率增益。同样，KGR随RIS元件的数量显着增加，而随着BS天线的数量，KGR的数量略有增加。
Reconfigurable intelligent surface (RIS) is a disruptive technology to enhance the performance of physical-layer key generation (PKG) thanks to its ability to smartly customize the radio environments. Existing RIS-assisted PKG methods are mainly based on the idealistic assumption of an independent and identically distributed (i.i.d.) channel model at both the base station (BS) and the RIS. However, the i.i.d. model is inaccurate for a typical RIS in an isotropic scattering environment and neglecting the existence of channel spatial correlation would possibly degrade the PKG performance. In this paper, we establish a general spatially correlated channel model and propose a new channel probing framework based on the transmit and the reflective beamforming. We derive a closed-form key generation rate (KGR) expression and formulate an optimization problem, which is solved by using the low-complexity Block Successive Upper-bound Minimization (BSUM) with Mirror-Prox method. Simulation results show that compared to the existing methods based on the i.i.d. fading model, our proposed method achieves about $5$ dB transmit power gain when the spacing between two neighboring RIS elements is a quarter of the wavelength. Also, the KGR increases significantly with the number of RIS elements while that increases marginally with the number of BS antennas.
