Optimising OFDM based visible light communication for high throughput and reduced PAPR

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.