Adaptive transmission based on instantaneous channel state information is an important methodology to improve data rates of mobile users, which requires the periodic update of channel variations. Different from radio frequency (RF) channels, whose variations are governed by Doppler and multi-path effects, visible light communication (VLC) channel variations are mainly related to receiver movements and rotations. In this article, a movement-rotation (MR) correlation function is proposed to measure VLC channel variations with the changes in receiver location and orientation. The correlation function of VLC channel gain in the time domain can then be approximated by the MR correlation function, which is an important criterion for the design of data transmission frames. It is verified that the approximation by MR correlation function can approach the actual simulation and experiment results of VLC channel gain correlation function in the time domain. In addition, experiment and simulation results are presented to investigate variation characteristics of VLC channels in different scenarios. It is shown that a receiver movement of several decimeters or a change of 10–20 degrees in the inclined angle of the receiver is required in a typical scenario in order to observe a distinguishable change of VLC channel gain.

中文翻译：

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VLC通道的运动-旋转（MR）相关函数和相干距离

基于瞬时信道状态信息的自适应传输是提高移动用户数据速率的重要方法，需要定期更新信道变化。与射频 (RF) 信道的变化受多普勒和多径效应控制不同，可见光通信 (VLC) 信道的变化主要与接收器的移动和旋转有关。在本文中，提出了一种移动-旋转 (MR) 相关函数来测量 VLC 信道随接收器位置和方向的变化而变化。VLC信道增益在时域的相关函数可以用MR相关函数近似，这是设计数据传输帧的一个重要标准。验证了MR相关函数的逼近在时域上可以接近VLC信道增益相关函数的实际仿真和实验结果。此外，还给出了实验和仿真结果，以研究不同场景下 VLC 信道的变化特性。结果表明，在典型场景中需要接收器移动几分米或接收器倾斜角 10-20 度的变化，才能观察到 VLC 信道增益的可区分变化。