In order to circumvent the throughput limitation imposed on visible light communication (VLC) systems by the limited LED bandwidth, optical orthogonal frequency division multiplexing (OFDM) with non-uniform bit-loading is studied in this paper. By using lower order modulation on subcarriers that suffer the most distortion, we show that it is possible to establish a high throughput and reliable OFDM based VLC link at a sampling rate of six times the available system bandwidth. The high signal peak-to-average-power-ratio (PAPR) that accompanies the OFDM signal is however reduced by adopting the pilot symbol phase rotation technique previously proposed by the authors. With this, over 4 dB reduction in the electrical PAPR is attainable. This combined approach thus make it possible to achieve high throughput without incurring the high PAPR penalties.
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