On Energy Efficiency of Visible Light Communication Systems

The reuse of the omnipresent LED lights for visible light communication (VLC) as a short-range data carrier may be an environmentally-friendly add-on to the radio frequency-based mobile network and make several new applications feasible. However, this comes with the price of additional lighting device complexity and also with lower energy efficiency, which can be measured by its consumption factor (CF) representing the data rate to the extra energy expense ratio (bits/J). This article addresses the choice of driver circuit type and data modulation strategy in a framework based on the known VLC channel, LEDs, and circuit models. Four applications of VLC are considered in the analysis: Li-Fi, virtual reality (VR), indoor localization (IL), and vehicular communication (VC). The main findings are that the reduced bit load and increasing bandwidth occupied by the modulation harm the efficiency of switching mode converters used as modulators, which were found to be cost-effective at low data rate applications of VLC, such as IL and VC. On the other hand, in higher data rate applications such as Li-Fi and VR, linear mode modulators are surprisingly more energy-efficient even when an extra step of power conversion is necessary to control average light or step down an unregulated supply voltage.