A Novel ACO-OFDM System Based on Fast Walsh Hadamard Transform

Visible Light Communication (VLC), an alternative to radio frequency (RF), was born as a promising technology. In VLC systems, orthogonal frequency division multiplexing (OFDM) has received much attention due to its high data rate, simple equalization and robustness against inter symbol interference (ISI). However, high peak to average power ratio (PAPR) and LED non-linearity have remarkable effects on the performance of indoor VLC-OFDM systems. Asymmetrically clipped optical OFDM (ACO-OFDM) is a technique that sacrifices spectral efficiency to transmit a unipolar frequency division multiplexed signal over a unipolar channel. In this study, fast Walsh Hadamard transform based ACO-OFDM (FWHT-ACO-OFDM) method is proposed to improve the performance of ACO-OFDM system by recovering this spectral efficiency. The performance of the proposed method is verified by computer simulation studies for bit error rate (BER) and PAPR performance criteria. From the simulation consequence, it is seen that the proposed method is better for both performance criteria than ACO-OFDM methods.