Optimising the inter‐distance between transmitters in a multi‐cell VLC system

Abstract

In this study, the authors find the optimum inter-distance between visible light access points (VAPs) in a multi-cell system. This is an important issue to avoid the lack of resources resulting from wiring too few VAPs while minimising the installation cost. This study uses a one-dimensional corridor model suitable for many practical environments such as train aisles and hospital/library corridors. They provide formulas for the average rate achieved per user to determine the optimal inter-VAP distance. These formulas depend on information that is usually available in the design step such as the corridor dimensions, luminaries' parameters, and user density. They consider different power allocation techniques and different frequency reuse factors. The analysis shows that the optimum inter-VAP distance depends mainly on the corridor dimensions and not as much on the communication technique. Higher frequency reuse factors reduce the interference and improve the performance in the case of small cells. Specifically, the results determine the corridor dimensions that are better served by multi-VAP rather than a single centred VAP. Many important design issues are answered throughout this study such as how the ceiling height and the estimated crowdedness in the corridor affect the optimum cell size.