> Why under water visible light communication MIMO systems ?
Visible Light Communication (VLC) is an emerging technology that intends to enable high speed communication links primarily in indoor environments and works on the principle of intensity modulation of solid-state lighting infrastructures provided by light-emitting diodes (LEDs). Visible Light Communication systems offer several key advantages over traditional radio-frequency based communication networks including over 300 THz of license-free bandwidth on visible wavelengths which is enormously larger than that available in radio and since VLC consumes very less amounts of power, the VLC system is a power efficient system. Underwater wireless communication is expected to play an important role in investigation of climate change, monitoring biological, biogeochemical, evolutionary, and ecological processes in sea,ocean, and lake environments, in unmanned underwater vehicles which are used to controland maintain oil production facilities and harbors, submarines, ships, divers and buoys.
> How under water visible light communication is done ?
Basically there are 3 possible methods for underwater wireless communication.
1. Radio frequency (RF) communication
2. Acoustic communication
3. Visible light communication
In visible light communication, normally the existing underwater VLC systems normally consist of light emitting diodes (LED’s) at the transmitter end and photo diodes at the receiver end. Voltages detected at the receiver are amplified to decode the transmitted data.
> What are the major drawbacks in this system and proposed methods to overcome those ?
When visible light propagates through aqua mediums, they get affected from attenuation and absorption. To overcome these drawbacks and to increase the speed of data transmission, we are developing the existing method from previous phase of the project . We are using,
1. A transmitter made of 100 LEDs
2. A camera as a receiver
As this extends for a turbulent flow we are planning to use machine learning techniques with image processing. This will help to train the receiver to identify LED locations in the transmitter more specifically.
Under Water Visible Light MIMO Communication System with a Camera Receiver
M.S.M. Akram, L.G.D. Aravinda, M.K.P.D. Munaweera, M.P.B. Ekanayake, G.M.R.I. Godaliyadda
This is the paper published by last year group regarding their project for under water visible light MIMO communication system.
Design and Implementation of Under Water Optical Communication System
Ziad T. Al Dahan , Samar Y. Al Dabagh and Asmahan Assad
This paper describes about designing of a underwater optical communication system using laser diodes. It further describes about modulating, demodulating and about implementing the channel for underwater communication.
These two videos give a rough idea about a similar underwater visible light data communication system developed by a group of Engineering undergraduates from University of Ruhuna. They have used blue LEDs as it has the lowest wave length. This helps it to travel faster in aqua mediums