Nyquist-PAM-4 transmission using linear DPD and MLSE for indoor visible light communications

350Mbit/s Nyquist-PAM-4 signal is experimentally transmitted over 2-m distance in visible light communication system, which only uses 46-MHz limited system bandwidth. The system bandwidth is expanded with linear digital pre-distortion (DPD), and the strong inter-symbol interference (ISI) caused by Nyquist filter is compensated by maximum likelihood sequence estimation (MLSE) algorithm. The experimental results indicate that the performance of VLC system can be effectively improved with proposed technique.