Adaptive MIMO-CSK camera-based VLC system for vehicle-to-vehicle communications.

Abstract

This thesis investigates the bit-error probability of circular color shift keying (CSK) constellations in a Visible Light Communications (VLC) scenario with a camera-based receiver. The impact of the distance between the transmitter and the receiver is illustrated. The noise at the receiver is investigated and transferred from the spacial domain to an angular noise in the International Commission on Illumination (CIE) color domain, where it is shown to behave similarly to a Gaussian distribution. Based on this approximation, a closed-form expression of the bit-error rate (BER) of circular CSK constellations is derived. Simulation results show that this closed-form BER approximation holds for BER ranges corresponding to VLC applications of practical interest. This approximation is also extended to a scenario with diversity using selection combining, where results show that signi cant BER improvements are obtained. Also, Multiple Input Multiple Output (MIMO) system is illustrated to increase symbol rate, and the trade off between the symbol rate and BER is analyzed. Finally, a link adaptation approach maximizing the number of bits per transmitted symbol, while meeting a target BER, is proposed based on the obtained BER results with and without diversity.