Experimental Demonstration of a Cubic-Receiver-Based MIMO Visible Light Communication System

An experimental demonstration of a nonimaging multiple-input multiple-output (MIMO) visible light communication (VLC) system based on a cubic receiver is reported in this paper. The receiver is designed to have five photodetectors as a cubic structure to solve the problem of an ill-conditioned channel matrix. The experiment employs four independent white light-emitting diodes (LEDs) as transmitters. Each of them transmits a different bit stream with orthogonal frequency-division multiplexing (OFDM) modulation and a bit-and-power allocation algorithm. By measuring the highest achievable overall data rate in the typical illumination scene, the performance of the multiplexing gain of the system is demonstrated. The experimental results reveal that the highest spectral efficiency is about 14.5 bit/s/Hz, and the multiplexing gain is up to 2.134 times at the center point among four LEDs. Besides, the system can support user mobility in real time, since it does not require the receiver adjustment and alignment.