A Novel Method of Integrating Visible Light Communications Within LED Drivers

Although visible light communication (VLC) systems hold great promise for ubiquitous connectivity, the efficient implementation of drivers which support illumination and communication functions is an open problem. In this paper, we present a novel approach to integrate VLC within light-emitting diode (LED) drivers by replacing the freewheeling diode with a light-emitting device termed a light-emitting freewheeling diode (LEFD). In this way, energy typically dissipated in the power converter can be used to provide illumination. Subtle changes to the control signal of the converter can be used to convey data from the LEFD while simultaneously supporting illumination functions. We consider a variety of modulation formats and provide simulation results quantifying performance. A prototype buck converter with LEFD is implemented and efficiency and efficacy are measured. It is demonstrated that the addition of an LEFD can improve the overall optical efficiency (i.e., efficacy) over conventional LED converter designs.