3.075 Gb/s underwater visible light communication utilizing hardware pre-equalizer with multiple feature points

We propose a flexible method for multiple feature frequencies-based bridge T hardware pre-equalizer that can better match the channel of an LED-based visible light communication (VLC) system and dramatically increase the system capacity. Based on this method, three kinds of equalizers are fabricated with the same maximum attenuation but different envelopes of frequency response. The performance of the three equalizers is experimentally compared in an underwater VLC system. The results show that the different shapes of the pre-equalizer can significantly impact the system SNR as well as the system capacity. By utilizing one of the optimally designed equalizers, an overall data rate of 3.075 Gb/s underwater VLC system can be achieved based on 64 QAM discrete multitone modulation over 1.2-m water channel. The measured bit error rate is under the hard decision-forward error correction threshold of 3.8 × 10 − 3.