Indoor visible communication utilizing plural white LEDs as lighting

Future electric lights will be composed of white LED (light emitting diodes). Indoor wireless optical communication systems utilizing white LED lights have been proposed in our laboratory and we have been studying it. Generally, plural lights are installed in our room. Therefore, their optical path difference must be considered. In this paper, the influence of optical path difference has been investigated and two approaches for this problem are introduced. One uses OOK-RZ (on-off keying, return-to-zero) coding and the other uses optical OFDM (orthogonal frequency division multiplexing). From the results of computer simulations, we have found that these approaches are feasible for wireless optical communication systems utilizing white LED lights.