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Visible light communications (VLCs) have received extensive attention in the research community thanks to their advantages of high bandwidth, low cost, robustness to electromagnetic interference, operation in an unregulated spectrum, and high degree of spatial confinement in indoor scenarios. One of the main limitations for high data-rate transmission in VLC systems is the limited modulation bandwidth...
Channel characterisation for indoor visible-light communication systems is revisited. The purpose of this study is to evaluate the channel frequency selectivity, or in other words, the significance of inter-symbol interference (ISI) at the receiver and the necessity of channel equalisation to recover the transmitted data. The authors focus on the effect of the indoor channel by assuming no bandwidth...
Carrier-less amplitude and phase (CAP) modulation has recently been considered as an alternative to optical orthogonal-frequency-division-multiplexing (O-OFDM) in visible light communication (VLC) systems. The main advantages of CAP over O-OFDM are its lower implementation complexity at the transmitter side and its lower peak-to-average power ratio. Here, we consider CAP modulation where matched filtering...
This paper presents simulation results that show the principle of implementing multi-band carrierless amplitude and phase (m-CAP) modulation enhanced by the decision feedback equalizer (DFE) for a bandlimited visible light communications (VLC) system. When deploying different number of sub-carriers m = {1, 2, 5, 10}, we show the bit error rate (BER) performance of m-CAP over a fixed system bandwidth...
Discrete multitone transmission (DMT) is a useful approach to cope with the dispersive nature of VLC indoor channels. In such environments, the dispersion occurs either due to the LED in combination with its driver and or the multipath propagation channel. In this paper, we consider the impact of both types of dispersions on the bit error rate performance of a DMT based Li-Fi system. However, the...
Through the numerical simulation of the channel impulse response, we investigate the limitation on the data rate due to multipath reflections for an indoor visible light communication system. Three different metrics of channel are studied for medium-sized and large rooms, namely the root-mean-square delay spread, 3-dB bandwidth, and signal-to-interference ratio. To focus on the channel effect, we...
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