Experimental demonstration of a 10BASE-T Ethernet visible light communications system using white phosphor light-emitting diodes

In this study, a compact design of a highly efficient, and a high luminosity light-emitting diode (LED)-based visible light communications system is presented, which is capable of providing standard room illumination levels and also wide-coverage Ethernet 10BASE-T optical wireless downlink communications over a distance of 2.3 m using commercial white light phosphor LEDs. The measured signal-to-noise ratio of the designed Ethernet system is >45 dB, thus allowing error-free communications with both on-off keying non-return zero and differential Manchester-coded modulation schemes at 10 Mbps. The uplink has been provided via a wireless infra-red link. A comparative study of a point-to-point wired local area network (LAN) and the optical wireless link confirms no discernible differences between them. The design of the transmitter is also shown to be scalable, with the frequency response for driving 25 LEDs being almost the same as driving a single LED. LED driving units are designed to match with the Ethernet sockets (RJ45) that conform to the existing LAN infrastructures (building and portable devices).