Performance Analysis of OFDM-Based VLC Schemes in NLOS Channels

In this paper, several Orthogonal frequency division multiplexing (OFDM)-based Visible light Communications (VLC) techniques designed for intensity modulation/direct detection (IM/DD) are evaluated and compared for various optical channels. Evaluations are done for line-of-sight (LOS) and no-line-of-sight (NLOS) channels. The techniques analyzed are asymmetrically clipped optical OFDM (ACO-OFDM), direct-current (DC) biased optical OFDM (DCO-OFDM), and asymmetrically clipped DC biased optical OFDM (ADO-OFDM). These schemes are evaluated and compared for different M-QAM modulations in terms of bit error rate (BER). It is shown that ACO-OFDM, in general terms, presents a better performance compared to the conventional DCO-OFDM and ADO-OFDM schemes.