Efficient Channel Coding for Dimmable Visible Light Communications System

Oluwaseyi Paul Babalola,Vipin Balyan

doi:10.1109/access.2020.3041431

Abstract

Visible light communication (VLC) offers wireless communication within short-range based on wavelength converters and light-emitting diode (LED). In the VLC system, conventional forward error correction (FEC) codes are not guaranteed to provide flicker mitigation and dimming support. Consequently, modified coding schemes are introduced for reliable VLC. These methods require complicated coding structures, use of lookup tables, and the addition of large redundancy, resulting to increased computational complexity and low transmission efficiency. In this article, we propose a coding scheme that is flicker-free and enhances the transmission efficiency for VLC systems. The proposed scheme is based on polar codes (PC) and Knuth balancing code with enhanced prefix coding technique. The results show that the proposed algorithm exhibits improved transmission efficiency compared to the PC without and with run-length limited code, for dimming values 75% (or 25%) and 87.5% (or 12.5%). Also, the proposed scheme presents a significant bit error rate (BER) performance gain compared to the schemes in literature. The proposed scheme is flicker-free, provides a simple encoding structure, does not utilize lookup tables, generates minimal number of redundancies for energy efficiency. Thus, the approach is flexible, and it is more suitable for real-time VLC systems.

Highlights

V ISIBLE light communication (VLC) offers an appealing and economical platform for both illumination and communication
In IEEE VLC standard [1], DC-balanced run-length limited (RLL) line codes such as Manchester codes or 1b2b are recommended for intensity modulation with direct detection (IM/DD) VLC systems to prevent flickering and provide dimming support
In this article, we presented an efficient flicker-free channel coding scheme based on concatenation of polar codes and modified Knuth code balancing algorithm for dimmable VLC

Summary

INTRODUCTION

V ISIBLE light communication (VLC) offers an appealing and economical platform for both illumination and communication. In IEEE VLC standard [1], DC-balanced run-length limited (RLL) line codes such as Manchester codes or 1b2b are recommended for intensity modulation with direct detection (IM/DD) VLC systems to prevent flickering and provide dimming support. Several enhanced FEC coding techniques that consider flicker mitigation and support dimming using compensation symbols (CS) have been proposed in the literature [2]–[7], to enhance the efficiency of coding and overall performance of VLC systems. We propose a dimming efficient and flickerfree FEC for VLC systems based on Knuth’s balancing algorithm [10] with enhanced prefix coding technique.

POLAR CODES

KNUTH’S BALANCING CODE

RESULTS AND ANALYSIS

RUN-LENGTH ANALYSIS

CONCLUSION