A 100 Mb/s visible light communications system using a linear adaptive equalizer

This paper presents experimental results demonstrating a > 100 Mb/s visible light communications (VLC) system using linear adaptive equalizers for the first time. In order to achieve high transmission speeds, generally the research community has adopted spectrally efficient modulation formats such as discrete multi-tone and equalizers are overlooked. The reason for this is unclear as equalizers offer a substantial capacity for removing inter-symbol interference. As a result, in this paper we implement a line-of-sight VLC link with an ~8 MHz bandwidth and a linear feedforward equalizer; the number of taps is varied in order to gain insight into the system performance using varying complexity. The 120 Mb/s transmission speed ultimately achieved offers a bit-rate to bandwidth gain of ~15 times.