Experimental demonstration of 50-Mb/s visible light communications using 4 x 4 MIMO

This letter reports the experimental demonstration of an indoor visible light non-imaging multiple input multiple output (MIMO) system with an aggregate error free bit rate of 50 Mb/s over a distance of 2 m. The system uses four independent white LED transmitters, each transmitting 12.5 Mb/s of data in the on-off keying non-return zero (OOK-NRZ) format, and four independent non-imaging optical receivers. The performance of four detection methods ranging from the basic channel inversion to the more advanced space time techniques is compared experimentally. The results gathered demonstrate that the simplest technique is capable of the same bit error rate (BER) as the most complex scheme. The system also provides full illumination with a mean level of 350 Lux satisfying the ISO lighting standards for home and office environments