Indoor optical wireless communication by ultraviolet and visible light

Visible light communication in conjunction with solid state lighting has become an emerging area of interest to achieve lighting and wireless communication simultaneously in an indoor environment. It is anticipated to be a low cost supplement to existing wireless communication technologies. Most existing work has primarily focused on a unidirectional downlink using visible light spectra. The appropriate choice of an uplink to achieve bidirectional communication is a big challenge. In this paper, candidate options of the uplink are compared in terms of device performance, light safety, background interference, and path loss. In visible light communication, white light emitting diodes as optical transmitters are also characterized in terms of impulse response and electrical spectrum. A digital preequalization idea to increase their bandwidth is proposed. Performance of the downlink visible light communication system is also experimentally studied in order to demonstrate the feasibility of the proposed design.