Visible Light Communication System with Changing Lighting Color

Visible light communication (VLC) is an emerging solution in the wireless connectivity, which is utilized for more personalized and multi-purpose wireless communication systems in complementation to radio-frequency (RF) based one. We developed LED-based transmitter module with an option of illumination color tuning, a reciprocal (photodetector) module and set a duplex wireless link using developed modules. We conducted a computer simulation of the microwave matching and bias circuits for LEDs, fabricated a test printed circuit board (PCB) and measured the scattering matrix parameters of this PCB. Based on the developed PCB and obtained experimental results the final layout of transmitter module was designed and fabricated. The illuminator of transmitter module consisted of 16 RGBW LEDs, matched in bandwidth up to 170 MHz, in order to maintain data speed transfer as high as 170 Mbit/s. The variation of illumination color was realized via DALI protocol. We tested the system with both natural and artificial light as noise source. We conducted the experiment of data transmission via developed and fabricated VLC system and managed to achieve the EVM value of 9%. Pseudo random binary sequence (PRBS) was used as data package and various modulation schemes were applied: QPSK, π/4-QPSK, APSK16, QAM16. Finally, we connected the transmitting module directly to the Global Internet and reciprocal module to the user PC and managed to achieve download and upload data speed up to 60 Mbit/s at up to 4 m distance between the modules.