High-Speed Bi-directional Optical Wireless System in Non-Directed Line-of-Sight Configuration

We propose and experimentally demonstrate the first bi-directional optical wireless link operating in non-direct line-of-sight (Nd-LOS). The system is based on visible light emitting diode (LED) for downlink and infrared LED for uplink. We achieve around 250 Mbit/s for both downstream and upstream transmission, with the ambient light noise of usual indoor illumination level (500 lx), produced by warm-white LED. 100 Mbit/s are guaranteed inside 12 m² of a common room scenario, without LOS tracking. An optimized discrete multi-tone modulation gives bit-error-ratios always below of the common forward-error-correction threshold of 1.5 ×10^-3. These results indicate that this scheme has great potential for practical VLC system implementation.