Multifunction LED Lighting System Combining Tunable Spectrum and Data Communication

A comparison of two different lighting systems combining tunable illumination, visible light communications (VLC) and sensing capabilities. The first method is based on light emitting diodes (LED) as light source and multifunction smart sensors and the second one with LEDs and micro-spectrometer to be included in the transceiver and/or receiver. Both systems are intended for future lighting sensor networks that combine standardized optical communications according the standard IEEE802.15.7 and sensing (illuminance, proximity, colour, and spectrum detection) for indoor envirIn this project a novel portable Visible Light Communication (VLC) system comprising an inexpensive and easy to fabricate multi-channel transmitter (Tx) and a receiver (Rx) have been developed. The light engine is designed to support up to three different LED channels while illuminating an indoor space changing the spectrum according to human circadian rhythms or any other desires. The Tx module architecture contains a programmable microcontroller and a constant current LED driver to manage the data to be transmitted. The Rx module allows the detection of optical signals, decoding and recovering the complete information with a circuit containing three stages: transimpedance amplifier, serializer and deserializer stages, controlled by a microcontroller unit. The VLC link has been tested in a laboratory environment with natural illumination to operate for distances up to 8 meters (at 700 kbps), data rates up to 4.50 Mbps (at 2 meters), and angles up to 75º (at 700 kbps and 2 meters). Under these conditions the flickering effect is completely removed