Channel Modeling and Characterization for Visible Light Communications

TLDR

The study presents a comprehensive channel modeling and characterization of visible light communications. Using ray‑tracing, the authors model visible‑light channels in diverse indoor settings, accounting for nonideal sources, specular and diffuse reflections, object geometry, wavelength‑dependent surface properties, and varying transmitter/receiver configurations to compute CIRs and key channel metrics. The results show that this method yields CIRs for nonideal sources with specular and mixed reflections, enabling extraction of channel DC gain, RMS delay spread, coherence bandwidth, and mean excess delay, and reveals distinct differences between infrared and visible‑light propagation.

Abstract

In this paper, we present a comprehensive channel modeling and characterization study for visible light communications. Our study is based on ray tracing, which allows for an accurate description of the interaction of rays emitted from the lighting source within a specified confined space. Contrary to existing works, which are mainly limited to ideal Lambertian sources and purely diffuse reflections, our approach is capable of obtaining channel impulse responses (CIRs) for any nonideal sources, as well as specular and mixed specular-diffuse reflections. Furthermore, we can precisely reflect the presence of objects (e.g., furniture) and wavelength-dependent reflection characteristics of surface materials (e.g., ceilings, floor, walls, and furniture) in a channel study. As case studies, we consider a number of indoor environments with various dimensions and different surface materials, i.e., plaster, gloss paint, wood, aluminum metal, and glass. We further consider various scenarios with different transmitter specifications (i.e., single versus multiple transmitters and array type) and receiver specifications (i.e., location and rotation). For each environment, we obtain CIRs and present a channel characterization study where channel parameters, such as channel DC gain, root mean square (RMS) delay spread, coherence bandwidth, and mean excess delay, are obtained. We also make one-to-one comparisons between infrared and visible-light CIRs for the same environments to emphasize the differences between two optical bands.