Fair Non-Orthogonal Multiple Access for Visible Light Communication Downlinks

This letter investigates a downlink power control strategy for visible light communication (VLC) systems with non-orthogonal multiple access. Our goal is to maximize sum throughput of the multiuser VLC systems subject to both user fairness and unique intensity constraints for optical modulations. Though the original problem is nonconvex, we first transform it into an equivalent convex one by introducing auxiliary variables and applying variable transformation. Then, we present an optimal power control algorithm with low complexity. Numerical results show large rate gains compared to the conventional OFDM scheme.