Frequency-Domain Channel Characteristics of Intelligent Reflecting Surface Assisted Visible Light Communication

Deploying an intelligent reflecting surface (IRS) array in visible light communication (VLC) systems forms additional light propagation paths, thereby enhancing the optical wireless channel. This improves the aggregated received signal strength, but on the other hand, it also introduces time delays between received signals via different paths. In this paper, the impact of IRS-induced time delay on the VLC channel characteristics in the frequency-domain is investigated for the first time in the open literature. The considered issue is experimentally validated. In addition, the influence of IRS-induced time delay in practical scenarios considering users with fixed and random positions has also been evaluated. It is demonstrated that an IRS array can consistently improve the performance of narrowband VLC systems. In wideband VLC systems, the performance gain is considerable when the reflected channel via the IRS array is significantly greater than the line-of-sight (LoS) channel. However, when the path losses for both reflected and LoS signals are similar, the communication performance does not show noticeable improvement compared to the case with only the LoS path.