LIFI TECHNOLOGY

GROUP 2
K. Akhila 21568T1517

M. Priyadarshini
21568T1518 O.
GUIDE AND HOD : Sreeja Mam Sunitha 21568T1521
V.
Akhila 21568T1537
 CONTENT

 A B S T RA C T
 INTRODUCTION
 H I S T O RY
 WORKING PROCESS
 WHY VISIBLE LIGHT
C O M M U N I C AT I O N ?
 LI-FI VS WI-FI
 FUTURE POSSIBILITIES
 A D VA N TA G E S
 A P P L I C AT I O N S

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ABSTRACT
Whether you're using wireless internet in a coffee shop, stealing it from the guy next door, or competing for
bandwidth at a conference, you've probably gotten frustrated with the slow speeds you face when more than
one device is tapped into the network. As more and more people and their many devices access wireless
internet, clogged airwaves are going to make it increasingly difficult to latch onto a reliable signal. But radio
waves are just one part of the spectrum that can carry our data. What if we could use other waves to surf the
internet? One German physicist Dr. Harald Haas, has come up with a solution he calls "Data Through
Illumination"- taking the fiber out of fiber optics by sending data through an LED light bulb that varies in
intensity faster than the human eye can follow. It's the same idea behind infrared remote controls, but far
more powerful. Li-Fi provides better bandwidth, efficiency, connectivity and security than Wi-Fi and has
already achieved high speeds larger than 1 Gbps under the laboratory conditions. By leveraging the low-cost
nature of LEDs and lighting units, there are lots of opportunities to exploit this medium.

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INTRODUCTION
In simple terms, Li-Fi can be thought of as a light-based Wi-Fi. That is, it uses light instead of radio waves to
transmit information. And instead of Wi-Fi modems, Li-Fi would use transceiver-fitted LED lamps that can light
a room as well as transmit and receive information. Since simple light bulbs are used, there can technically be
any number of access points. This technology uses a part of the electromagnetic spectrum that is still not
greatly utilized- The Visible Light Spectrum. Light is in fact very much part of our lives for millions and millions
of years and does not have any major ill effect. More over there is 10,000 times more space available in this
spectrum and just counting on the bulbs in use, it also multiplies to 10.000 times more availability as an
infrastructure, globally. It is possible to encode data in the light by varying the rate at which the LEDs flicker on
and off to give different strings of Is and Os. The LED intensity is modulated so rapidly that human eyes cannot
notice, so the output appears constant.

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 HISTORY

Harald Haas, a professor at the University of Edinburgh who began his

research in the field in 2004, gave a debut demonstration of what he called
a Li-Fi prototype at the TEDGlobal conference in Edinburgh on 12th July
2011. He used a table lamp with an LED bulb to transmit a video of clouds
onto a laptop connected to the prototype. During the event he periodically
blocked the light from lamp to prove that the lamp was indeed the source
of incoming data. At TEDGlobal, Haas demonstrated a data rate of
transmission of around 10Mbps broadband connection. Two months
comparable to a fairly good UK later he achieved 123Mbps.

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WORKING PROCESS
The working of Li-Fi is based on a very simple concept, when the LED is on, a digital 1 is transmitted, and when it
is off, a digital 0 is transmitted. The LEDs can be switched on and off very quickly, which gives nice opportunities
for transmitting data.

The Li-Fi technology is based on the Visible Light Communication which uses the visible light for data
communication. In VLC, we use a source of illumination which can not only produce illumination but also send
information using the same light. So we can say that VLC is illumination along with communication.

Data transmission of Li-Fi 6

Li-Fi is a fast and cheap optical version of Wi-Fi, the technology of which is based on Visible Light Communication (VLC). VLC is a
data communication medium, which uses visible light between 400 THz (780 nm) and 800 THz (375 nm) as optical carrier for
data transmission and illumination. It uses fast pulses of light to transmit information wirelessly. The main components of this
communication system are:

i. a high brightness white LED, which acts as a communication source and

ii. a silicon photodiode which shows good response to visible wavelength region serving as the receiving element.

LED can be switched on and off to generate digital strings of Is and Os. Data can be encoded in the light to generate a new data
stream by varying the flickering rate of the LED. To be clearer, by modulating the LED light with the data signal, the LED
illumination can be used as a communication source. As the flickering rate is so fast, the LED output appears constant to the
human eye. A data rate of greater than 100 Mbps is possible by using high speed LEDs with appropriate multiplexing
techniques. VLC data rate can be increased by parallel data transmission using LED arrays where each LED transmits a different
data stream. There are reasons to prefer LED as the light source in VLC while a lot of other illumination devices like fluorescent
lamp, incandescent bulb etc. are available, and the prime reason among then is its high flickering rates.

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WHY VISIBLE LIGHT
C O M M U N I C AT I O N ?

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The frequency spectrum that is available to us in the atmosphere consists of many wave regions like X-rays, gamma rays, ultraviolet
region, infrared region, visible light rays, radio waves, etc. Anyone of the above waves can be used in the upcoming communication
technologies but why the Visible Light part is chosen? The reason behind this is the easy availability and lesser harmful effects that
occur due to these rays of light. VLC uses the visible light between 400 THz (780 nm) and 800 THz (375 nm) as medium which are
less dangerous for high-power applications and also humans can easily perceive it and protect themselves from the harmful effects
whereas the other wave regions have following disadvantages:

• Radio waves are expensive (due to spectrum charges) and less secure (due to interference and possible interception etc.)
• Gamma rays are harmful because it could be dangerous dealing with it, by the human beings due to their proven adverse effects
on human health.
• X-rays have health issues, similar to the Gamma Rays.
• Ultraviolet light can be considered for communication technology purposes at place without people, otherwise they can also be
dangerous for the human body when exposed continuously.
• Infrared, due to high safety regulation, can only be used with low power.

Hence the Visible light portion (from red to blue) of the electromagnetic spectrum does not cause any harm to the people as visible
rays are safe to use, provide larger bandwidth and also have a promising future in the communication field.

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COMPARISON WITH WI-FI

There are several advantages of Li-Fi over Wi-Fi:

• Li-Fi uses light rather than radio frequency signals so are intolerant to disturbances.
• VLC could be used safely in aircraft without affecting airlines signals.
• Integrated into medical devices and in hospitals as this technology doesn't deal with radio waves, so it can easily be
used in all such places where Bluetooth, infrared, Wi-Fi and internet are broadly in use.
• Under water in sea Wi-Fi does not work at all but light can be used and hence undersea explorations are good to go
now with much ease.
• There are billions of bulbs worldwide which just need to be replaced with LED's to transmit data.
• Security is a side benefit of using light for data transfer as it does not penetrate through walls.
• On highways for traffic control applications like where Cars can have LED based headlights, LED based backlights,
and they can communicate with each other and prevent accidents.
• Using this Technology worldwide every street lamp would be a free data access point.
• The issues of the shortage of radio frequency bandwidth may be sorted out by Li-Fi.

The table on the next page shows the comparison of Li-Fi with Wi-Fi on various parameters.

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FUTURE
POSSIBILITIES
Li-Fi is purely a technology of future. It is having a potential to take over all the internet
market on its own. The main points to be noted here are as follows:

• With the advancement of Li-Fi technology, it will become more portable, taking its
rightful places in our phones and laptops.
• It will give the field of IoT a considerable boost as more and more number of devices
will be able to connect and interact with each other through Li-Fi.
• We will also be able to access the internet in places like Hospitals and Airplanes
where traditional network systems can never be used.
• Underwater communication will become much easier with the use of Li- Fi.
• In future, it may be possible that we will be having an internet with a speed of multi
gigabits per second.
• With Li-Fi, we will also be moving towards a much more secured network, which will
be safeguarding us from unwanted hackers.
• Depletion of Environment due to increased use of radio frequencies will also
decrease, as the Li-Fi technology uses the visible spectrum of light to transmit data.
• Installation will also not be an issue with Li-Fi.
• Multiuser support of Li-Fi will ensure that every individual is getting a high speed of
internet.

And these points will probably keep increasing as we will be moving forward towards
the future.
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ADVANTAGES

 Larger bandwidth
 High efficiency
 More availability
 Thousands and millions of street lamps can be
converted to Li-Fi spots.
 No license needed
 Green information technology
 Lighting spots used as hotspots
 The issues of the shortage of radio frequency
bandwidth may be sorted out by Li-Fi.
 This technology worldwide can be used for every street
lamp would be a free data access points. 13
APPLICATIONS

Smart Healthcare Educational

Lighting Communication Environments

Mobile Underwater Vehicles and

Connectivity Communication Transportation
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T H A N K YO U

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