用可变形天线提升恶劣环境下的无线密钥生成速率
A Fluid Antenna Enabled Physical Layer Key Generation for Next-G Wireless Networks
- 用可变形天线阵列动态调整位置，结合优化算法提升密钥生成能力
- 相比传统固定天线，密钥生成率提升35.42%（PSO）和67.73%（AO）
- 适合高安全性要求的下一代无线网络，尤其在复杂传播环境中
物理层密钥生成（PLKG）是一种无需安全基础设施即可从无线信道中生成秘密密钥的有前景技术。然而，在恶劣传播环境下，信道特性恶化，密钥生成率（KGR）显著下降。本文提出一种基于流体天线（FA）的PLKG系统以解决该问题。首先推导出FA阵列的密钥生成率闭式表达式，并通过粒子群优化（PSO）算法联合优化预编码矩阵与天线位置。为降低计算复杂度，进一步设计了结合投影梯度下降（PGD）与PSO的交替优化（AO）算法。仿真结果表明，利用额外的空间自由度（DoF），所提FA系统优于传统固定位置天线（FPA）阵列和可重构智能表面（RIS）。与传统均匀平面阵列（UPA）相比，分别在PSO与AO算法下实现35.42%和67.73%的KGR性能提升。
原文摘要 · Abstract (English)
As a promising physical layer security technique, physical layer key generation (PLKG) enables legitimate users to obtain secret keys from wireless channel without security infrastructures. However, in harsh propagation environments, the channel characteristic becomes unsatisfactory, the key generation rate (KGR) is significantly deteriorated. In this paper, we propose a novel fluid antenna (FA) enabled PLKG system to address this challenge. Specifically, we first derive the closed-form expression of the KGR for FA array, and then jointly optimize the precoding matrix and the antenna positions via a particle swarm optimization (PSO) algorithm. Next, to further reduce the computational complexity of the optimization procedure, we develop an alternating optimization (AO) algorithm, which combines the projected gradient descent (PGD) and the PSO. Simulation results demonstrate that by exploiting the additional spatial degree of freedom (DoF), our FA enabled PLKG system is superior to the benchmarks, such as the conventional fixed-position antenna (FPA) array and the reconfigurable intelligent surface (RIS). It is worth highlighting that compared to the conventional uniform planar antenna (UPA), the FA enabled PLKG achieves a 35.42\% KGR performance improvement under PSO algorithm and a 67.73\% KGR performance improvement under AO algorithm, respectively.
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