3-Gbit/s Indoor Visible Light Communications Using Optical Diversity Schemes

A 3-Gb/s high-speed indoor visible light communication system using optical diversity schemes is presented. A double optical diversity (DOD) scheme in time and frequency is employed with selection combining (SC) on the basis of red, green, and blue (RGB) light-emitting diodes (LEDs). In the proposed scheme, the original data and the delayed versions of this data are transmitted simultaneously by multiplying with orthogonal frequency in order to create diversity effect over the transmission. In addition, RGB LEDs are used for parallel transmission of data, thus resulting in an increase in the data speed. At the receiver, color filters are used to filter out for the desired signal, and SC is performed to obtain the most probable bits. Simulation results demonstrate that the proposed scheme is robust and efficient to overcome the effect of multiple reflections with a link margin of approximately 10 dB, as compared with a conventional on-off keying (OOK) modulation scheme at a bit error rate (BER) of 10^-6. Moreover, the scheme achieves a data rate of 3 Gb/s with a BER of 10^-6 at a signal-to-noise ratio (SNR) value of 3.6 dB over most locations in an indoor visible light communication (VLC) environment.