Optical IRS for Visible Light Communication: From Optics Model to Association Model

Optical intelligent reflecting surface (OIRS) offers a new and effective approach to resolving the line-of-sight blockage issue in visible light communication (VLC) by enabling redirection of light to bypass obstacles, thereby dramatically enhancing indoor VLC coverage and reliability. Currently, two primary OIRS channel models exist, the optics model and the association model, each offering advantages under different conditions. However, a comparative analysis of their respective benefits and drawbacks is notably absent in the existing literature. This article thus provides a comprehensive overview of OIRS for VLC from a channel modeling perspective, with particular emphasis on the association model for its analysis tractability. First, we present the characteristics of OIRS-reflected channels in multiple domains and introduce two models, which are then compared in terms of applicable conditions, configuration methods, and channel parameters. Next, under the more practically appealing association model, we discuss the key design techniques for OIRS-aided VLC systems, including beam alignment, channel estimation, and OIRS reflection optimization. Finally, open issues are identified to stimulate future research in this area.