This project is based on transformation of data like text, voice, audio and image through underwater using visible light. This is major application in military like navy and submarines, scientific community for underwater research, flood detection, climatic changes , oceanography and more . The cost of this budget around 15k to 17k.

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ABSTRACT
Underwater wireless information transfer is of great interest to the military, industry, and
the scientific community, as it plays an important role in tactical surveillance, pollution
monitoring, oil control and maintenance, offshore explorations, climate change monitoring,
and oceanography research. There is an increase in the number of unmanned vehicles or
devices deployed underwater, which require high bandwidth and high capacity for
information transfer underwater. In order to facilitate “Underwater Optical Wireless
Communication”(UOWC) is used. In this project, We are presenting a complete model to
transfer text, images and audio from one device to another through underwater channel
using Visible light communication. We are tend to work with Arduino UNO and Raspberry pi
3B. In which transmitter transmits the encrypted data through visible light using Arduino
UNO through underwater and the receiver at the receiving end identifies the transmitted
encrypted data and sent to Raspberry pi .We connected a phototransistor connected to the
USB to TTL converter which is plugged into Raspberry Pi’s USB port and We are running a
Processing sketch on Raspberry Pi to receive the image and text to display it on screen and
audio in speaker. We are able to establish visible light communication at baud rate 9600 bps.
This project not only provides exhaustive research in underwater optical communication but
also aims to provide the development of new ideas that would help in the growth of future
underwater communication system resulting in high data rates, low latency and an energy-
efficient system.

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Chapter 1 INTRODUCTION
Light Fidelity known as Li-Fi is a visible light communication which is used for high speed
communication. The name Li-Fi is due to the similarity of the working of Wi-Fi except light
source instead of radio waves. The Li-Fi technology was first proposed by Harald Hass a
German physicist, number of industry groups and companies combined form the Li-Fi
association to promote the high speed wireless communication using VLC technique to
overcome the shortage in spectrum distribution for the purpose of high speed wireless
communication. The technology is demonstrated for the first time in los Vegas using a pair of
smart phones up to the distance range of 10 meters. The data is send in the way of light rays
that has been generated using LED light source the intensity of the light source as been
increased by reducing the amplitude of the digital data that as to be transmitted. In the last
few years, the interest towards optical wireless communication has increased for terrestrial,
space and underwater links as it is capable of providing high data rates with low power and
mass requirement. Many of researchers have carried out work for terrestrial and space links.
The present technology uses acoustic waves for underwater communication whose
performance is limited by low bandwidth, high transmission losses, time varying multipath
propagation, high latency and Doppler spread. In this project we are implementing Optical
Underwater communication which is still not used, whose performance is high bandwidth,
low transmission losses, low latency and high energy efficient system.
In the Electromagnetic spectrum consists of Radio-waves, Infrared rays, Ultraviolet rays, X-
rays, Gamma rays and Visible light. Radio-waves are insufficient spectrum for increasing
data, Infrared rays has low power application, Ultraviolet rays dangerous for Marine life, X-
rays and Gamma rays generally can’t use hence Visible light used in electromagnetic suitable
for Optical wireless Underwater communication.
A. OBJECTIVE AND SCOPE OF THE PROJECT
This Project aims to provide an overview of various challenges and current technologies used
in UOWC system. Various experiments, future perspectives, and applications are presented
in this paper. Through this project, the author is highlighting the relatively less explored
technology of UOWC which is a potential alternative solution for low cost and less powered
devices. The scope of this project is to determine the performance of UOWC system for
variety of mode of transmitted data and develop a realistic system design model for
underwater optical channel. This project focuses on various interesting features in rapidly
varying underwater channel that affects the reliability and feasibility of underwater optical
communication link. Various technologies that improve the efficiency of UOWC system.
These technologies not only provide an energy efficient system but also improves the
capacity and range for the applications that demands real time text, audio and image
through underwater network.

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I. FUTURE SCOPE
UOWC is a complementary technology to conventional acoustic links as it provides high data
rates with no latency over moderate distances. This helps in reducing power consumption
and thereby, promotes reliable underwater monitoring and surveillance applications for
longer time durations. UOWC finds its applications in environmental monitoring, data
collection (such as water temperature, Ph etc.), oil/gas monitoring and security. With the
ongoing research and developments in this field, UOWC will provide an efficient and robust
way of communication between surface vehicles, underwater devices and sea floor
infrastructure. Due to low cost, small size, less power consumption and compatibility with
other optical systems, it finds its application in heterogeneous network environments or in
dense underwater wireless sensor networks. A hybrid communication system using a dual
mode (acoustic and optics) transceiver is capable of providing very high data rates and can
be used for assisting underwater robotic sensor networks. In case of high turbid underwater
environment, the system can switch to low data rate acoustic transceiver, thereby,
increasing the reliability of the communication link. There are still many areas that require
extensive research and investigation for long term survival of UOWC. There is need to dig
more into fundamental insights and develop new approaches in communication to make
UOWC a reality in near future. For this, there is a need for further investigation and analysis
of new theoretical models (both analytical and computational) to better understand the
laser beam propagation through randomly varying underwater channel. It may also include
the modeling of solar penetration, multiple scattering mechanisms and reflections from sea
surface, etc. Extensive field experiments and use of test beds are essential to have better
understanding of underwater environment and channel characterization. In order to
improve the overall robustness in different underwater conditions, there is a need to explore
adaptive techniques that can optimize communication efficiency and save more energy. As
there are many obstacles to establish end-to-end communication links between source and
destination nodes, there is a need to investigate more into spatial diversity techniques and
routing protocols (such as proactive protocols, geographical routing protocols, reactive
protocols, etc.). Higher layers of network architecture that include medium access, data link
control, transport control and application layers need to be investigated for designing a
practical UOWC link. Though there is little work carried out with different modulation or
multiple access techniques however, it has been shown that UOWC are capable of providing
high speed optical links for short range applications. Further, the reliability of wireless
optical communication in unreliable oceanography environment can be improved with the
use of error control coding techniques. There is a lot of work being done to produce simple,
cost effective, low powered, robust and real time sensor systems. Various non-acoustic
sensors such as optical sensor, electro-mechanical sensor bio-inspired sensors and MEMs
based sensors have also been developed for underwater applications. All these sensors are
tailored for specific applications and are specially designed to withstand the underwater
environmental conditions such as bio-fouling, limited energy resource, corrosive nature of
sea water, pressure resistant enclosures, etc. Besides all these remarkable efforts, there is
still room for future developments in producing more robust, cheap, adaptive and highly
stable underwater optical sensors. This will not only guarantee long term survivability under
dynamic conditions but will also avoid frequent and costly rescue operations.

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Chapter 2 Literature Survey
Lot of literature isavailable forthe advancementof underwateracousticcommunicationbutvery
lessworkisavailable forUOWC.The literaturesthatare available forUOWC doesnotprovide a
holisticcoverage of the topic. the authorfocusedoncommunicationlinkmodelsbyprovidingthe link
performance basedonthese models.A reportbyD. Anguitahighlightsthe prospectsandproblemsof
optical wirelesscommunicationforapplicationsin the fieldof sensornetworks. The author
highlightedthe measuringtechniquesinoceanicoptical propertiesbutitlackstoprovidesthe
readerswithbasicbackgroundinUOWC. the author focusedonthe underwater.
HaraldHaas, a professoratthe Universityof Edinburghwhobeganhisresearchinthe fieldin2004,
gave a demonstration of what he called a Li-Fi prototype at the TED Global conference in Edinburgh
on 12th July2011.He useda table lampwithanLEDbulbto transmitavideoof bloomingflowersthat
wasthenprojectedontoascreenbehindhim.Haasdemonstratedadatarate of transmissionof
around10Mbps comparable toafairlygoodUKbroadbandconnection.Twomonthslaterhe
achieved123Mbps.Germanscientistssucceededin creating an 800Mbps capable wireless network
by using normal red, blue, green and white LEDlightbulbs,thusvariousotherglobalteamsare also
exploringthe possibilities.
Now-a-days,majorityof usare familiarwithWi-Fi (WirelessFidelity),whichgenerally uses2.4,5 ghz
radiofrequenciestotransmitdatawirelessly.But,these radiowavesare harmful forlivingbeings.So,
the bestalternative forthisproblemisVisible LightCommunication(VLC),where LEDlightsare used
to transferthe data wirelessly. VLCisrecentlyreferredasLi-Fi.Itisa termoftenusedto describe high
speedVLCinapplicationscenarioswhere Wi-Fimightalsobe used.The termLi-Fi issimilartoWi-Fi
withthe exceptionthatlightratherthanradioisusedfor transmission.ProfessorHaraldHaas,from
the Universityof Edinburghinthe UK,is widelyrecognizedasthe original founderof Li-Fi.Bythe end
of AUGUST 2015, data ratesof over1.6 GBPS were achievedusingLi-Fi (lightfidelity).InAPRIL2016,
the RussiancompanyStinsComanhas announcedthe developmentof aLi-Fi wirelesslocal network
calledBeamCaster.Theyachieveddataratesof 1.25 GBPS.With li-fi we canable tocommunicate
underwatergivesmore securitycomparestoWi-fi.

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Chapter 3 TECHNOLOGY USED
Block diagramof Transmitter Section
Block diagramof ReceiverSection
Fig 3.1 Block diagramof UOWC
The systemdesign for UOWC in fig 3.1 consists of a source that generates the information to
be transmitted which is then modulated on the optical carrier to be transmitted to longer
distances with a high data rate. The transmitter is equipped with projection optics and beam
steering elements in order to focus and steer the optical beam towards the position of the
receiver. The information bearing signal is then allowed to propagate through the
underwater channel whose characteristics vary according to the geographical location and
time. At the receiving end, the collecting optics collects the incoming signal and passes it to
the detector for optical-to-electrical conversion. The electrical signal is then allowed to pass
through a signal processing unit and a demodulator for recovering to the original
transmitted signal.
Audio
Light Transmitter
LED Driver
Amplifier
Image
ARDUINO
Text
USB
TTL
conve
Encoder
Underwater Channel
Light Receiver
AmplifierDecoder
Raspberry pi 3B
Speaker
Display
Photo Detector
PC
wi
yh
TT
L

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A. TRANSMITTER
Transmitter part includes PC, ARDUINO, UNO, Encoder, Amplifier and Light Transmitter. PC
which is with Audio, Text and Image that can be converted into Binary using MATLAB and
sends to AURDINO UNO and then encodes data by Encoder and amplifies encoded data and
sends to Li-fi module which has Light transmitter transmits data through Underwater
channel. Depending upon the requirement and keeping in mind that underwater systems
have power and mass constraints, the choice of LED or laser may vary in the blue-green
portion of the spectrum. Generally, for buoy system operating in shallow water, blue-green
LEDs are preferred. In case of systems operating in deep clear ocean water, laser based
systems are preferred. The output power of lasers or LEDs in blue-green spectrum ranges
from 10 mW to 10 W. Both LEDs and lasers have their own pros and cons while making
decision for the source in UOWC system. Lasers have fast switching time and high optical
power but LEDs are cheap, simple, less temperature dependent and more reliable.
I. ARDUINO UNO
Fig 3.2 ARDUINO UNO
Microcontroller ATmega328
Operating Voltage 5V
Input Voltage
(recommended)
7-12V
Input Voltage (limits) 6-20V
Digital I/O Pins 14 (of which 6 provide PWM output)
Analog Input Pins 6
DC Current per I/O Pin 40 mA
DC Current for 3.3V Pin 50 mA
Flash Memory
32 KB (ATmega328) of which 0.5 KB used by
boot loader
SRAM 2 KB (ATmega328)
EEPROM 1 KB (ATmega328)

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Clock Speed 16 MHz
II. MATLAB PROGRAMMING FOR PROCESSING THE IMAGE
For sending laptop progam, first we have to read the image. Common function to read an
image in MATLAB is inread(‘filename’). The image is converted from rgb image into gray
image. This is done so because if we want send a rgb color image we will have create 3
vector fields which makes the programming quite complex. After reading the image file the
serial COM port 25 is selected to interface the program code with Arduino Mega. The
baudrate of Arduino is selected as 9600 and then the whole image matrix is transmitted with
a pause of 0.001s and fwrite function. In the receiving laptop program, first the COM port 2
of the Arduino Mega is selected through which the bits are received. Then the command of
receiving 10 bits at a time is given. The bits are then received until the whole matrix is
transmitted. The bits are also stored in matrix form by creating the rows and columns from
the array. The constructed image from the matrix is then shown on the screen.
Fig. 3.3 Loaded Program in ARDUINO
B. RECEIVER
Receiver part includes Photo detector, Amplifier, Decoder, Raspberry Pi 3B, Speaker and
Display. The encoded data get received by Photo detector and decodes that received data
with use of Decoder and Amplifies received data by Amplifier and send to Raspberry Pi. We
are running a Processing sketch on Raspberry Pi to receive the image and text to display it
on screen and audio in speaker. We are able to establish visible light communication at baud
rate 9600 bps. The transmitted light is made to illuminate on receiver which is Si photodiode.
The information received by photodiode is converted into electrical pulses. A trans
impedance amplifier is used to convert electrical pulses to voltages. These voltages are then
fed to comparator to deal with distortion in the signal. Then the signal is fed to digital signal

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modulator which separates data signal and carrier signals. Thus obtained demodulated data
signal is given to Raspberry Pi for reframing and then send it to receiver Speaker and Display.
I. RASPBERRY PI 3B
Fig. 3.4 RASPBERRY PI 3B
 Raspberry pi 3 model b adds wireless LAN and Bluetooth connectivity making it the ideal
solution for powerful connected designs.
 Raspberry pi 3 use Processor chipest Boardcom BCM 2837 64 bIT ARMv7 Quad Core
processor powered Singel Board Computer running at 1200MHz.
 Raspberry pi 3 model b RAM : 1GB SDRAM@400MHz .
C. Hardware Requirements
I. Light Transmitter
1. PC with MATLAB code
2. ARDUINO UNO
3. Encoder
4. Amplifier
5. LED Driver
II. Light Receiver
1. Photo detector
2. Decoder
3. Raspberry pi 3B
4. Speaker

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5. Display
D. Software Requirements
1. MATLAB
2. ARDUINO 1.0.5 IDE

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Chapter 5 METHODOLOGY
A. Objectives
This Project aims to provide an overview of various challenges and current technologies used
in UOWC system. Various experiments, future perspectives, and applications are presented
in this paper. Through this project, the author is highlighting the relatively less explored
technology of UOWC which is a potential alternative solution for low cost and less powered
devices. The scope of this project is to determine the performance of UOWC system for
variety of mode of transmitted data and develop a realistic system design model for
underwater optical channel. This project focuses on various interesting features in rapidly
varying underwater channel that affects the reliability and feasibility of underwater optical
communication link. Various technologies that improve the efficiency of UOWC system is
also discussed in this paper. These technologies not only provide an energy efficient system
but also improves the capacity and range for the applications that demands real time text,
audio and image through underwater network.
I. IMPLEMENTATION OF ARDUINO UNO FOR TRANSMITTING DATA
ARDUINO module sends data serially. A program is loaded in the module for the image,text
and voice data using sketch ARDUINO 1.0.5 IDE software. In this implementation, COM port
25 is used to send the upcoming data bit by bit from the sending MATLAB program. The data
after converting into a serial bit stream than transferred through the output pin of ARDUINO
mega to the input of transistor amplifier circuit which contains the LED array.
II. ENCODER
Encoder encodes the binary form of data like text, audio and image which required to
transmit. Sends the encoded data to Li-Fi module which transmits the data to the
underwater channel.
III. LIGHT TRANSMITTER
The use of blue-green array of LEDs has been widely used in UOWC. LEDs can support
variable data rates up to Mbps and have high electrical to optical efficiency. The main issue
with LEDs is its wide spectral bandwidth i.e., 25 - 100 nm and therefore, it requires wide
band pass filters which in turn causes solar background noise to enter the system. Therefore,
LEDs are only used for short range communication eg., to connect underwater sensors and
drivers , for long range applications lasers are the preferred choice.
IV. LIGHT RECEIVER
A photo detector operates as light receiver which consists of data by converting light signals
that hit the junction to a voltage or current. The junction uses an illumination window with
an anti-reflect coating to absorb the light photons. The result of the absorption of photons is
the creation of electron-hole pairs in the depletion region. Examples of photo detectors are

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photodiodes and phototransistors. Other optical devices similar to photo detectors are solar
cells which also absorb light and turn it into energy. A similar but different optical device is
the LED which is basically the inverse of a photodiode, instead of converting light to a
voltage or current, it converts a voltage or current to light.
V. DECODER
Decoder decodes the received data at the photo detector through underwater channel and
it sends the decoded data like text, audio and image to the Raspberry Pi 3B.
VI. IMPLEMENTATION OF RASPBERRY PI FOR SIGNAL PROCESSING
We connected a phototransistor connected to the USB to TTL converter which is plugged
into Raspberry Pi’s USB port, A program is loaded in the module for the image, text and
voice data using sketch software and We are running a Processing sketch on Raspberry Pi to
receive the image and text to display it on screen and audio in speaker. We are able to
establish visible light communication at baud rate 9600 bps.
B. ADVANTAGES AND CHALLENGES OF UOWC
4.1 Advantages
4.1.1 Huge bandwidth
It exhibit almost unlimited and unlicensed bandwidth which approximately ranges from 380
to 780 nm. Therefore, VLC has 350 THz that can support multi-gigabit-per-second data rates
with LED arrays in a multiple-input multiple-output (MIMO) configuration. This makes VLC a
good alternative to the indoor IR that operates at 780–950 nm for the access technologies
4.1.2 Low power consumption
VLC provides both communication and lighting, giving Gbps data rates with only
unsophisticated LEDs and photo detectors that consume low power compared to costly RF
alternatives that demand high power consumption for sampling, processing, and
transmitting Gbps data.
4.1.3 Low cost
The required optical components such as LEDs and photodetectors are inexpensive,
compact, lightweight, amenable to dense integration, and have very long lifespan
Moreover, with large unlicensed optical spectrum as well as much lower power-per-bit cost
compared to the RF communications, VLC is relatively cheaper.
4.1.4 No health concerns
VLC does not generate radiation that leads to public health concern. Besides, it lowers the
carbon dioxide emission owing to the little extra power consumption for communication
purposes.

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4.1.5 Inherent security
VLC offers comparatively higher security due to the fact that it is highly intricate for a
network intruder that is outside to pick up the signal .
4.1.6 Energy Efficiency System
Optical communication but also aims to provide the development of new ideas that would
help in the growth of future underwater communication. A hybrid approach to an optical
underwater communication system is presented that complements the existing acoustic
system, resulting in high data rates, low latency, and an energy efficieny system.
4.2 Challenges
A. Background noise
Background noise must be taken into account while designing UOWC link. Noise is strongly
dependent upon operating wave length and geographical location. Ingeneral, deep ocean is
less noisy than harbor side (such as marine work site) due to man made noise. Most of the
noise sources in underwater environment are described as continuous spectrum and Gaussian
profile. The main sources of background noise are: (i) diffused extended back ground noise,
(ii) background noise from the Sun or other stellar objects and (iii) scattered light collected by
the receiver.
Fig 5.4.1 Geometry of (a) extended source when ꭥFOV<ꭥs and (b) stellar or point
source when ꭥFOV > ꭥs (ꭥFOV is the solid angle of receiver field-of-view of the
receiver and ꭥs is the solid angle field-of-view of the source).
B. Multipath Interference and Dispersion
Just like in acoustic communication, multipath interference is produced in optical
underwater channel when an optical signal reaches the detector after encountering multiple
scattering objects or multiple reflections from other underwater bodies. This eventually
leads to waveform time dispersion (time spreading) and decreases the data rate due to ISI.
However, the effect of multipath interference is not much pronounced in UOWC in
comparison to acoustic communication due to very large speed of light. The amount of
multipath interference depends upon system specifications and the propagation
environment. For shallow water environment, optical waves reflected from surface or

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bottom generate multiple signals at the detector for oceans, these surface and bottom
reflections can be ignored. Advanced signal processing techniques such as channel
equalization and adaptive optics are used at the receiver to suppress interference. Although
channel equalization for fast varying underwater channel seems to be a big challenge,
however, careful characterization of underwater optical channel can help to choose
appropriate system design parameters for reliable and high quality optical link. Work done
by authors in and is focused on channel time dispersion leading to ISI. In a polarized light is
used to analyze the effect of transmission distance on time dispersion and it has been
concluded that ISI is very substantial for long range communication (50 m) at high data rate
(1 Gbps). The effect of system design parameters like transmitter beam divergence and
receiver aperture size is studied in to quantify channel timed is persion in UOWC the channel
time dispersion can be neglected when working over moderate distances. Therefore, UOWC
is capable of supporting high data rates at moderate distances. The effect of ISI on the
performance of 25 m coastal water link at two different data rates i.e., 0.5 Gbps and 50 Gbps
with spatial diversity. It is observed that spatial diversity helps in reducing the effect of
multipath interference by partially compensating for ISI degradation, especially for low data
rates. However, its performance degrades at high data rates specially for high signal to noise
ratio (SNR).
C. Physical Obstruction
As the optical beam is very narrow, any living organism such as school of fish or marine
animals will cause momentary loss of signal at the receiver. This requires the use of
appropriate error correction techniques, signal processing techniques and redundancy
measures to ensure re-transmission of data when lost. The two most widely used error
correction techniques in underwater environment is automatic repeat request (ARQ) and
forward error correction (FEC). ARQ allows for re-transmission of data after data time out
session. However, it does not provide constant throughput which decreases rapidly during
high BER cases. In FEC, source coding is performed where redundant bits are encapsulated
with data bits to increase the robustness of the message. However, this process increases
the payload of the transmission. Another technique called hybrid ARQ which is a
combination of ARQ and FEC is used to improve the reliability of UOWC system. Signal
processing techniques also help in improving the optical link quality and make the system
robust against physical obstruction. A 1 Mbps UOWC system was developed using signal
processing capabilities to enhance the propagation distance. Hop-to-hop communication
approach is beneficial in error prone underwater network. A multi-hop underwater optical
communication system is developed that can support a bandwidth up to 100 kHz for
communication range of 1 m.

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Chapter 5 APPLICATIONS AND RESULTS
1. Underwater wireless information transfer is of great interest to the military, industry,
and the scientific community.
2. it plays an important role in tactical surveillance, pollution monitoring, oil control and
maintenance, offshore explorations, climate change monitoring, and oceanography
research
3. The remote control devices under the Ocean where Radio waves doesn’t work.
4. Most of the fields like Marine Research, Navy, Submarines, Trade and other major
activity carried out through water communication, for all those activities must needed
better Underwater Communication there should implement the optical wireless
Communication.
5. The underwater wireless communications are a process of transmitting data in unguided
water environments via wireless carriers such as acoustic wave, RF wave, and optical
wave. Compared to the RF or acoustic alternatives, UOWC offers higher data rate and
transmission bandwidth. Basically, the UOWC uses optical wave as wireless carrier for an
unguided data transmission. The UOWC systems are applicable in disaster precaution,
offshore exploration, environmental monitoring, as well as military operations.
Nevertheless, UOWC systems are susceptible to absorption and scattering which are
normally created by the underwater channels. These conditions lead to severe
attenuation of optical wave and eventually hindered the system performance. Different
viable techniques have been presented in the project to attend to the associated
technical challenges of a UOWC. One of such is an underwater wireless sensor network
(UWSN). Figure 5.1 depicts a UWSN with aerospace and terrestrial communications.
Figure 5.1 UWSN with aerospace and terrestrial communication.

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A. Expected Outcome of the Proposed Study
The experiment is proposed through underwater using Visible light. The received signal from
Decoder is then processed through Raspberry PI and displays image and text , and voice in
speaker.
System Performance Analysis
Parameters Optical through
Underwater
Data rate ~ Gbps
Attenuation 0.39 dB/m
Latency Low
Energy
Efficiency
≈ 30,000 bits/Joules
Table 5.1 Values of different Parameters
Table 5.2 Various modes of transmission and its Parameters
In this point to point communication network, the whole image array takes time to transfer
from the transmitter laptop to the receiver display. When the transmitter circuit sends bits it
shows ‘ready sending’ and when the receiver circuit receive bits it shows ‘go receiving’ on
the MATLAB command window. After sending the whole image, audio and text of the sender
MATLAB window confirms it by displaying ‘finished’ while the receiver shows ‘showing
results’ and displays image and text on Display and audio on speaker.
B. Plan of work
Mode of Transmission Measuring Parameters
Text Data rate (~kbps), Latency, Bandwidth(MHz)
and Energy Efficiency(bits/Joules).
Audio Data rate (~kbps), Attenuation, Latency,
Bandwidth(MHz) and Energy Efficiency(bits/Joules).
Image Data rate (~kbps), Latency, Bandwidth(MHz)
and Energy Efficiency(bits/Joules).
SL NO MONTH WORK
1 October Literature Review
2 November Collecting Hardware components
3 December Studying Hardware and Software
4 January Implementation the software design
5 February Implementation the Hardware design
6 March Overall Review Implementation
7 April Project Report Submission

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II. CONCLUSION
An improvement in underwater communication system is needed due to increased number
of unmanned vehicles in space and underwater. Traditional underwater communication is
based on acoustic signals and despite the substantial advancement in this field, acoustic
communication is hard pressed to provide sufficient bandwidth with low latency. RF signals
for UOWC can only be used at ELF due to the high absorption of electromagnetic signals at
radio frequencies. The use of optical fibers or co-axial cables limit the range and
maneuverability of underwater operations. Optical underwater communication provides
great potential to augment traditional acoustic communication due to its high data rates,
low latency, less power consumption and smaller packaging. Also, this technology can
benefit meaningfully from the progress made in the terrestrial optical wireless
communication. However, the distance and scope of optical beam underwater is affected by
water type, abortion, scattering and various other propagation losses. UOWC makes use of
blue-green wavelength of visible spectrum as it offers low attenuation window and provides
high bandwidth communication (in the order of MHz) over moderate distances (10 - 100 m).
Moreover, a typical UOWC having point-to-point link requires strict pointing and tracking
systems specially for mobile platforms. The use of smart transmitter and receivers,
segmented FOV or electronic beam steering can relax the strict requirement of point and
tracking for narrow optical beam. Also, in order to make the link workable for different
underwater scenarios and prevent the loss due to LOS, various link configurations like retro-
reflective, diffused and NLOS links are discussed in this survey. For an efficient and reliable
underwater optical link, a profound knowledge of channel model, system architecture,
system components and materials, modulation techniques, operating wavelength and it
influence in underwater environment has to be well understood. We conclude that though
acoustic waves are the robust and feasible carrier in today’s scenario but with rapid
technological development and active ongoing research in UOWC, this technology will be
more promising with game-changing potentials in the near future.

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