A Novel CSK Modulated OFDM System for Visible Light Communication

Abstract

In this paper, color shift keying (CSK) modulation, which is selected as one of the modulation methods in visible light communication systems, is integrated with orthogonal frequency division multiplexing (OFDM) to increase the spectrum yield. However, the conventional fast Fourier transform (FFT) based OFDM needs that the CSK symbols be Hermitian symmetric, resulting in wasted bandwidth. In this study, it is proposed a real Fourier field based CSK OFDM technique using discrete Cosine transform (DCT), which can transform the real-value signal into a real-value signal and eliminate the need for Hermitian symmetry. Thus, the use of spectra has been doubled due to the removal of Hermitian symmetry in classical FFT-based OFDM systems. In order to test the achievement of the recommended CSK-modulated DCT-based OFDM (DCT-OFDM) and compare with the classical FFT-based OFDM and discrete sine transform (DST) based OFDM systems computer simulation studies are carried out in additive white Gaussian noise (AWGN) channel environment and a single path channel in indoor environment, where the transmitter and the receiver see each other (Line of sight, LOS). From the computer simulation outcomes, it is observed that approximately 17 dB of SNR gain is obtained with the proposed method for the 1E–3 BER value.