This book examines an indoor visible light communication system in detail. The indoor VLC system’s transmitter, indoor channel, and receiver are all investigated. The effect of LED and PD spatial separation on multipath channel BER performance has been studied. In addition, the effect of different LED radiation patterns on the BER performance of a multipath indoor VLC system has been evaluated. The BER and frequency response of an OFDM-based integrated PLC-VLC system were examined for various room sizes. The BER, sum rate, and outage probability of the downlink multipath multi-user NOMA-VLC system were probed using various LED semi-angle and power allocation coefficient values. Furthermore, LED nonlinearity mitigation in a NOMA-OFDM VLC system has been proposed and tested using a combination of Precoder and Companding. Besides, a hybrid combination of TDMA and cooperative NOMA system for an integrated RF/VLC system based on SWIPT has been suggested to reduce SIC complexity. Finally, a concave-convex lens for MIMO visible light communication (VLC) systems that provides more received power than conventional lenses has been proposed.