Performance Analysis of various Pre-Equalization techniques for Visible Light Communication

Abstract

Abstract Visible Light Communication (VLC) is a well known emerging technology for indoor communication that has drawn more attention in recent years. The name itself indicates that the medium to transfer data in VLC technology is the light that travels in free space. During VLC Inter-Symbol Interference (ISI) in free space channel occurs due to reflectivity of surfaces like walls and ceiling. In order to overcome this problem an inverse filter called equalizer is placed. Equalizers are feasible solution to improve the transmission performance. In this paper, the performance of VLC system is analyzed with various pre-equalization techniques using Optisystem V.16 simulation tool for a practically measured parameters since the spectrum of LED required equalization. This simulation is carried out by placing various equalizers such as Spaced Feed Forward Equalizer, Fractionally Spaced Feed Forward Equalizer, Decision Feedback Equalizer, Combination of both Feed Forward and Decision Feedback Equalizer and Adaptive Equalizer at transmitter side for different bitrates and different link ranges. With adaptive pre-equalization, this VLC system can support 2 Gbps data rate up to 5 m range with a Q factor of 8.52. Under the influence of external white light (noise) of power − 80dBm and below, the proposed system works well. Above − 80dBm, the modulated light is disturbed, so that the data obtained is slightly degraded.