Visible Light Communications Using Four-Color LEDs

Abstract

Visible light communications (VLC) technology has gained prominence in the development of high data rate transmission for the fifth generation (5G) networks. VLC technology can be used in conjunction with the existing Wi-Fi technology to improve access and data transmission. In optical wireless communications, LED transmitters are used in applications that desire mobility and the LED divergence enable larger coverage. VLC systems offer simultaneous data transmission and illumination. However, the LED’s limited modulation bandwidth and non-linear distortions pose difficulty in achieving high transmission data rates. Wavelength division multiplexing in VLC (WDM-VLC) can be used improve the data rates to meet gigabit data standards. This thesis work focuses on VLC experiments using WDM, discrete multitone modulation (DMT), and multi-input multi-output (MIMO) techniques. The VLC system is demonstrated over commercial four-color red-green-blue-amber (RGBA) LED transmitters in three cases of interest: (a) a single LED transmitter, (b) repetition encoding, and (c) spatial multiplexing. Our proposed VLC system used bit-power allocation strategies to maximize the data transmission under bit error rate (BER) threshold of 2×10-3, which is the typical hard-decision forward error correction (FEC) threshold.