The need for more efficient illumination systems has led to the proliferation of
Solid-State Lighting (SSL) systems, which offer optimized power consumption.
SSL systems are comprised of LED devices which are intrinsically fast devices
and permit very fast light modulation. This, along with the congestion of the
radio frequency spectrum has paved the path for the emergence of Visible Light
Communication (VLC) systems. VLC uses free space to convey information by
using light modulation. Notwithstanding, as VLC systems proliferate and cost
competitiveness ensues, there are two important aspects to be considered.
State-of-the-art VLC implementations use power demanding PAs, and thus it is
important to investigate if regular, existent Switched-Mode Power Supply (SMPS)
circuits can be adapted for VLC use. A 28 W buck regulator was implemented
using a off-the-shelf LED Driver integrated circuit, using both series and parallel
dimming techniques. Results show that optical clock frequencies up to 500 kHz are
achievable without any major modification besides adequate component sizing.
The use of an LED as a sensor was investigated, in a short-range, low-data-rate
perspective. Results show successful communication in an LED-to-LED configuration,
with enhanced range when using LED strings as sensors. Besides, LEDs
present spectral selective sensitivity, which makes them good contenders for a
multi-colour LED-to-LED system, such as in the use of RGB displays and lamps.
Ultimately, the present work shows evidence that LEDs can be used as a
dual-purpose device, enabling not only illumination, but also bi-directional data
communication
