Wavelength-Division Multiplexing of Channels for Visible Light Communication Through Free Space

Lim, Chia Wang (2019) Wavelength-Division Multiplexing of Channels for Visible Light Communication Through Free Space. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

Most communication systems using visible light can only transmit in one language due to the existence of a single channel. By adopting Wavelength Division Multiplexing (WDM) technique, this project allows three languages to be transmitted simultaneously through the creation of three individual channels. The result is a drastic saving in cost and implementation time. The three communication channels in this project are created by using three color lights (red, green and blue) derived from ultra-bright LEDs. Each color light represents one language. The three colors lights thus allow Malay, English and Chinese audio information to be transmitted and received simultaneously through free space without using optical fibers. As compared with communication using optical fibers, the advantages of Visible Light Communication (VLC) through free space are that it has high bandwidth, high data transfer rate and is immune from electromagnetic interference and hacking. LED light sources are used in preference to laser beams as unlike lasers, LEDs outputs are linearly proportional to the drive current, easier to use and have wider output patterns and longer lifespan. The project presented here is the first successful research on simultaneous multi-language transmission using visible light communication technique through free space, although research on multi-channel visible light communication through optical fibers has been widely conducted worldwide.