A Power efficient DST-based multicarrier and multiple access systems for VLC

Abstract

Visible Light Communication (VLC) exploits cost-effective light emitting diodes (LEDs) to render ‘illumination’ and ‘communication’ contemporaneously and is envisioned to meet the unprecedented growth in mobile data traffic. However, the slow transient response of white phosphorescent LEDs limits the modulation bandwidth. Consequently, orthogonal frequency division multiplexing (OFDM) is utilized to impart high data rate communication at the expense of emergence of high peak to average power ratio (PAPR). Furthermore, the limited dynamic range of LEDs makes this issue more pronounced as it leads to the emergence of detrimental non-linear distortions. This paper proposes discrete sine transform (DST)-based spreading for DC biased optical OFDM (DST-S-DCO-OFDM) to reduce PAPR. Unlike discrete Fourier transform (DFT)-based DCO-OFDM, DST-based DCO-OFDM doesn’t require Hermitian symmetry criteria to attain a real signal transmission. Accordingly, there is a reduction in computational complexity as well as increase in spectral efficiency. In addition, single carrier frequency division multiple access (SC-FDMA) is expedited for reducing PAPR. Therefore, this work derives the analytical expressions for DST-based optical interleaved multiple access (DST-OFDMA) and optical localized frequency division multiple access (DST-OLFDMA). The simulation results evidences that PAPR is decreased drastically by enforcing spreading technique when compared with conventional DST-based DCO-OFDM system. Furthermore, as depicted by the simulation results, the reduction in PAPR is more significant in DST-OFDMA than DST-OLFDMA. However, DST-OFDMA and DST-OLFDMA outperforms DST-based optical orthogonal frequency division multiple access (DST-OOFDMA).