Li-Fi uses visible light communication and LED bulbs to transmit data wirelessly. It was coined by Professor Harald Haas in 2011 as a wireless alternative to Wi-Fi that could increase available bandwidth. Li-Fi transmits data through rapid variations in LED light intensity faster than what the human eye can detect. It provides higher speeds than Wi-Fi, does not interfere with other devices, and the signal cannot pass through walls providing better security. While Li-Fi remains in development, potential applications include use in vehicles, aviation, underwater communication and hospitals.

1. LI-FI
LIGHT FIDELITY
PRESENTED BY:
ADITYA SAINI
B.TECH(CSE)

2. CONTENTS
2
• INTRODUCTION
• HISTORY
• PRESENT SCENARIO
• HOW DOES IT WORK
• LI-FI VS WI-FI
• APPLICATIONS
• CHALLENGES FOR LI-FI
• CONCLUSION

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INTRODUCTION
WHAT IS LI-FI ?
 LIGHT-FIDELITY
 Li-Fi, which uses visible light to transmit signals wirelessly.
Sending data through a LED light bulb that varies in intensity and faster
than human eye flickering. Li-Fi uses light emitting diodes (LEDs)
for high speed wireless communication.
 A Visible Light Communications (VLC) system which runs wireless communications
that travel at very high speeds. With Li-Fi, your light blub is essentially your router.
It uses common household LED light bulbs to enable data transfer.

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HISTORY OF LI-FI
The technology truly began during the 1990's in countries like
Germany, Korea, and Japan where they discovered LED's
could be retrofitted to send information. Harald Haas
continues to wow the world with the potential to use light for
communication. Professor Harald Haas coined the term "Li-Fi"
at his 2011 TED Global Talk where he introduced the idea of
"wireless data from every light". He is a Chair Professor of
Mobile Communications at the University of Edinburgh, and the
co-founder of pureLiFi.

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PRESENT SCENARIO
 A wireless network uses radio waves, just like cell phones, televisions and
radios do. They transmit at frequencies of 2.4 GHz or 5 GHz and use 802.11
networking standards, 802.11ac is the newest standard.
 With the explosion of rich online media, Internet of Things (IoT) and more
connected devices in your home, the demands on your home network are
continuously increasing. The American home has an average of 25 devices
connected to the Internet through WiFi this number is only expected to go up
significantly in the coming years.
 Each of these connected devices also have different bandwidth requirements
as they connect to the Internet at the same time. Present day WiFi routers are
not well equipped to handle the growing number of WiFi clients while ensuring
consistent connectivity and speed. One of the most common scenarios being
interference between WiFi routers due to channel crowding which is invisible to
the user, but slows your online experience.

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 Radio Spectrum is congested but the demand for wireless data
double each year. It seems everything want to use
wireless data but the capacity is drying up.
 Due to the increasing demand for wireless data communication,
the available radio spectrum below 10 GHz has become
insufficient.
 The available spectrum below 10 GHz will run out by 2020.
 Energy consumption is very large for RF systems..
ISSUES REGARDING RF SPECTRUM

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ISSUES REGARDING RF SPECTRUM
CAPACITY
SECURITY
AVAILIBILITY
ENERGY
EFFICIENCY
HEALTH
HAZARDS

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WHO CAN REPLACE RADIO WAVES FOR
WIRELESS COMMUNCATION

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HENCE WE ARE LEFT ONLY WITH THE VISIBLE - LIGHT
SPECTRUM.
“HERE COMES INTO PLAY LI-FI TECHNOLOGY”

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HOW DOES IT WORKS
 The intensity of the LEDs is varying by changing the current
passed through them at very high speeds. However, the human
eye cannot perceive this change and the LEDs appear to have
a constant intensity.
 This ON-OFF activity of LED lights enables data transmission
using binary codes i.e., when the LED is ON, logical ‘1’ is
transmitted and when the LED is OFF , logical ‘0’ is transmitted.
 Researcher has achieved speed up to 10 Gbps.

12. WORKING
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An overhead lamp fitted with
an LED with signal
processing technology
(below) streams data
embedded in its beam at
ultra-high speed to the photo
detector. A receiver dongle
then converts the tiny
changes in amplitude into an
electrical signal, which then
converted back into a data
stream and transmitted to a
computer or mobile device.

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14. LI-FI VS WI-FI
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15. POTENTIAL APPLICATION OF LI-FI:
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Li Fi technology is still in its infancy .However some areas where it seems perfectly
applicable are:
1. Vehicles
Vehicles could communicate with one another via front and back lights to
increase road safety. Street lights and traffic signals could also provide
information about current road situations.

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2. Aviation
Using this light-based data transmission will not interfere with equipment on
the aircraft that relies on radio waves such as its radar

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3. Underwater Communication
Most remotely operated underwater vehicles (ROVs) are controlled by wired connections.
The length of their cabling places a hard limit on their operational range, and other potential
factors such as the cable's weight and fragility may be restrictive. Since light can travel
through water, Li-Fi based communications could offer much greater mobility.

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4. Hospital
Many treatments now involve multiple individuals, Li-Fi systems could be a
better system to transmit communication about the information of patients.
Besides providing a higher speed, light waves also have little effect on medical
instruments and human bodies. Wireless communication can be done during
the use of such medical instruments without having to worry about radio
interferences hindering the efficiency of the task

19. ADVANTAGES OF LI-FI
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Efficiency
Li-Fi works on visible light technology. Since homes and offices already have LED bulbs
for lighting purposes, the same source of light can be used to transmit data. Hence, it is
very efficient in terms of costs as well as energy. Light must be on to transmit data, so
when there is no need for light, it can be reduced to a point where it appears off to human
eye, but is actually still on and working.
High-Speed
Data transmission over Li-Fi is a hundred times faster than data transmission over Wi-Fi.
At this speed, a high-definition video can be downloaded in mere seconds. Li-Fi can
deliver speeds as high as 1Gpbs.
No Interference
Li-Fi is also free from problems such as neighbouring network interference, radio
interference or interference generated due to sensitive electronics making it much more
energy efficient.

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Availability
Wherever there is a light source, there can be Internet. Light bulbs are present
everywhere – in homes, offices, shops, malls and even planes, meaning that
high-speed data transmission could be available everywhere.
Security
One main advantage of Li-Fi is security. Since light cannot pass through opaque
structures, Li-Fi Internet is available only to the users within a room and cannot be
breached by users in other rooms or buildings.

21. DISADVANTAGES OF LI-FI
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 Internet cannot be used without a light source. This could limit the locations and
situations in which Li-Fi could be used.
 Because it uses visible light, and light cannot penetrate walls, the signal's range
is limited by physical barriers.
 Sunlight will interfere the signals, resulting in interrupted Internet.
 Light cannot pass through objects, so if the receiver is inadvertently blocked in
any way, then the signal will immediately be cut out.
 Light cannot pass through objects, so if the receiver is inadvertently blocked in
any way, then the signal will immediately be cut out.

22. THANK YOU
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