Performance Evaluation of Visible Light Communication for DCO and ACO Optical OFDM Techniques

Abstract

Visible light communication (VLC) has evolved as a relatively new research topic that employs white light-emitting diodes for data transmission. The basic requirement for optical transmission is that signal should be real and positive. Among the various developed modulation techniques for VLC, orthogonal frequency division multiplexing (OFDM) has drawn major consideration because of its high data rate and heftiness to inter-symbol interference (ISI), but it suffers from the problem of high peak to average power ratio (PAPR), causing signal distortion thereby effecting the system efficiency. In this paper, asymmetrically clipped optical OFDM (ACO-OFDM) and direct current biased optical OFDM (DCO-OFDM) for VLC have been investigated by evaluating its bit error rate (BER) and PAPR performance. The effect of the uncorrelated noise due to dual-sided clipping of the signal, modulation order and number of subcarriers on the symbol distortion is also studied. Study on selection of optimum clipping levels is done to reduce the PAPR for both the schemes. Simulation analysis implies that ACO-OFDM is better than DCO-OFDM by around 4.5 dB for a BER of $\pmb{1\times 10^{-3}}$ and by about 2 dB for a PAPR complementary cumulative distribution function (CCDF) of $\pmb{1\times 10^{-1}}$.