Optical intelligent reflecting surface (OIRS) has been considered a promising technology for visible light communication (VLC) by constructing visual line-of-sight propagation paths to address the signal blockage issue. However, the existing works on OIRSs are mostly based on perfect channel state information (CSI), whose acquisition appears to be challenging due to the passive nature of the OIRS. To tackle this challenge, this paper proposes a customized channel estimation algorithm for OIRSs. Specifically, we first unveil the OIRS spatial coherence characteristics and derive the coherence distance in closed form. Based on this property, a spatial sampling-based algorithm is proposed to estimate the OIRS-reflected channel, by dividing the OIRS into multiple subarrays based on the coherence distance and sequentially estimating their associated CSI, followed by an interpolation to retrieve the full CSI. Simulation results validate the derived OIRS spatial coherence and demonstrate the efficacy of the proposed OIRS channel estimation algorithm.

翻译：光学智能反射面（OIRS）通过构建视距传播路径解决信号遮挡问题，已被视为可见光通信（VLC）的一项有前景技术。然而，现有OIRS研究大多基于理想信道状态信息（CSI），而由于OIRS的被动特性，CSI获取面临挑战。为应对这一难题，本文提出一种定制化的OIRS信道估计算法。具体而言，我们首先揭示OIRS的空间相干性特征，并推导出闭合形式的相干距离。基于该特性，提出一种空间采样算法实现OIRS反射信道估计：根据相干距离将OIRS划分为多个子阵列，依次估计各子阵列的关联CSI，并通过插值恢复完整CSI。仿真结果验证了推导的OIRS空间相干性，并证明了所提OIRS信道估计算法的有效性。