Optimization of SINR and Illumination Uniformity in Multi-LED Multi-Datastream VLC Networks

Abstract

Visible Light Communication (VLC), which is a recent technology that operates at the visible light spectrum band, is a very propitious technology complementary to RF in the era of spectrum crisis. Because of the extensive deployment of energy efficient Light Emitting Diodes (LEDs) and the advancements in LED technology with fast nanosecond switching times, VLC has gained a lot of interest recently. In this paper, we consider a downlink VLC architecture which is capable of providing simultaneous lighting and communication coverage across an indoor setting. We design a multi-element hemispherical bulb which transmits multiple data streams from its LEDs to mobile receivers. The architecture employs a Line-of-Sight (LOS) alignment protocol to tackle the hand-off issue caused by the mobility of the receivers in the room. We formulate an optimization problem that jointly addresses the LED-user associations as well as the LEDs’ transmit powers in order to maximize the Signal-to-Interference plus Noise Ratio (SINR) while taking into consideration an acceptable illumination uniformity constraint across the room. We propose a near-optimal solution using Geometric Programming (GP) to solve the optimization problem, and compare the performance of this GP solution to low complexity heuristics.