Downlink scheduling in visible light communications

Visible Light Communication (VLC) using Light Emitting Diodes (LEDs) within the existing lighting infrastructure would reduce the implementation cost and may operate at higher throughput than RF or Infrared (IR) based wireless systems. One of the major concerns in VLC implementation is developing resource allocation schemes that maintain or increase channel throughput, ensure fairness and fast link recovery while reducing delay. To address this challenge, the characteristics of VLC channel is modeled in detail mathematically and the resource allocation problem is formulated for a centrally controlled indoor VLC system in this paper. We focus on a VLC system providing location based services and it is shown that the resource allocation problem can be solved by optimal scheduling, and the solution has to consider different transmission scenarios based on different transmitters and receivers´ locations. Specifically, a scheduling algorithm using proportional fair principle is proposed and the simulation results demonstrate that the proposed algorithm outperform the maximum rate scheduling and round robin by balancing the user throughput and fairness among users. A prototype of the VLC system is currently under development to demonstrate the effectiveness of the proposed system.