Li-Fi is a wireless optical networking technology that uses light-emitting diodes (LEDs) for data transmission. It was coined by Harald Haas at the University of Edinburgh in 2011. Li-Fi provides higher speeds and more bandwidth than Wi-Fi, with the added benefit of not interfering with other wireless networks. Li-Fi works by varying the rate at which an LED light flickers on and off, which encodes data. Products like Li-Fi 1st and Li-Flame have been developed to transmit data through LED lights at speeds up to 5Mbps downlink and 5Mbps uplink within a range of 3 meters. Solar Li-Fi uses existing LED lights and solar panels to transmit

1. Li-Fi Technology

2. Wi-Fi
 Wi-Fi is a technology that allows electronic devices to connect to a
wireless LAN (WLAN) network.
 It mainly uses the 2.4 gigahertz UHF and 5 gigahertz SHF ISM radio
bands.
 Wi-Fi compatible devices can connect to the Internet via a WLAN
network and a wireless access point. Such an access point has a range
of about 20 meters (66 feet) indoors and a greater range outdoors.
 The Wi-Fi Alliance defines Wi-Fi as any "wireless local area network"
(WLAN) product based on the IEEE 802.11 standards

3. Different Wi-Fi Protocols and Data Rates
Protocol Frequency Signal Max. Data Rate
Legacy 802.11 2.4 GHz FHSS or DSSS 2 Mbps
802.11a 5 GHz OFDM 54Mbps
802.11b 2.4 GHz HR-DSSS 11Mbps
802.11g 2.4 GHz OFDM 54Mbps
802.11n 2.4 or 5 GHz OFDM 600Mbps
802.11ac 5 GHz 256-QAM 1.3Gbps

4. History Of Li-Fi
 Harald Haas, who teaches at
the University of Edinburgh
in Scotland, coined the term
"Li-Fi" at his TED Global
Talk in 2011.
 He gave a second TED
Global lecture in 2015 on the
use of solar cells as Li-Fi
data detectors and energy
harvesters.

5. Challenges faced by radio spectrum
Capacity
Scarce, Expensive,Lesser Bandwidth
Efficiency
Huge amount of energy needed to cool the base station cabins
Availability
Unavailable in aircrafts
Security
Radio waves penetrate through walls

6. Electromagnetic Spectrum

7. Advantages Of Using Visible Light
Capacity
We have 10,000 times more spectrum
Efficiency
This is data through illumination, high energy efficiency of LED bulbs
 Availability
Light is available everywhere. It can be used in airports, hospitals
Security
Light does not penetrate walls.

8. Infrared rays in Remote control
 Remote controls creates a simple,
low-speed data stream in 10,000
bits per second.
 With Li-Fi we transmit thousands
of data streams in parallel, at even
higher speeds.

9. Working Of Li-Fi
Operational procedure is very simple, if the led is on, you transmit a
digital 1,if its off you transmit a digital 0.
The LEDs can be switched on and off very quickly, which gives nice
opportunities for transmitting data.
Hence all that is required is some LEDs and a controller that code
data into those LEDs.
We have to just vary the rate at which the LED’s flicker depending
upon the data we want to encode .

10. How It Works

11. Li-Fi system connecting devices in a room

12. Modulation Techniques
On-off keying
• On-off keying (OOK) denotes the simplest form of amplitude-shift
keying (ASK) modulation
• Presence of a carrier for a specific duration represents a binary one
• Absence of carrier for the same duration represents a binary zero
• It is analogous to unipolar encoding line code.
• It is very easy to generate and decode

14. Li-1st
The first product to be
developed by pure LiFi
This is the worlds first Li-
Fi system
Full duplex
communication with a
capacity up to 5Mbps
downlink x 5Mbps uplink
Has a range of up to three
meters.

15. Li-1st Ceiling Unit
 Li-1st Ceiling Unit is
connected to the data network
via a standard Ethernet RJ45
port.
 It encodes the data and
transmits it by modulating the
intensity of the LED light.
 The Li-1 st ceiling unit receives
and decodes the uplink signal
using an infra-red detector and
optics.

16. Li-1st Desktop Unit
 A visible light decoder captures
the continuous sequence of light
intensity changes.
 It then decode the binary stream
and transmit it to the client device
via an USB connection.
 The desktop unit receives data
from the client device, encodes it
and transmits it to the ceiling unit
using an infra-red emitter.

17. Li-Flame
 The Li-Flame is the world’s
first high-speed wireless
network solution using VLC.
 Multiple APs throughout an
indoor space allow users to
move from one AP to the
next
 There is no interruption in its
high-speed data stream

18. Li Flame Ceiling Unit
 Data and power via standard
Ethernet port
 Simple installation
 Connects to an LED light fixture to
form an atto-cell over a wide area
 Multiple access
 Handover control enables seamless
switching between APs

19. Li Flame Desktop Unit
 Connects to client device via
USB
 10Mbps infrared uplink to ceiling
unit
 allows user to move from one
AP to the next without losing the
high-speed data connection
 Transceiver swivel head can be
adjusted by user to optimise the
connection
 Battery-powered and portable

20. Solar Li-Fi
Harald Haas at TED Global
2015 demonstrated solar li-fi.
He showed transmission
of video from a standard
off-the-shelf LED lamp to a
solar cell with laptop acting as
receiver.

21. Solar Li-Fi
 The point is to use existing infrastructure like solar panel and
LEDs to close the digital divide and to connect billions of
devices to internet .
 The Li-Fi prototype relies on solar energy to power Internet
connections
 An LED light source paired with a solar panel becomes a
fully functional transmitter and receiver system for high
speed, secure data transfer
 It is possible to use solar cells on the roof of a hut to act as a
broadband receiver from a laser station on a close by hill.

22. Applications
 Aero planes  Remote operated vehicles in sea

23. Applications
 Petro chemical plants  Traffic control

24. Applications
 Hospitals  In shops

25. Limitations 0f Li-Fi
 Light does not penetrate walls so signal contained to one area.
 For ideal speeds line of sight is required.
 A major challenge facing Li-Fi is how the receiving device
will transmit back to transmitter.
 Interferences from external light sources like sun light, normal
bulbs, and opaque materials in the path of transmission will
cause interruption in the communication

26. Conclusion
 So, all we would need to do is to fit a small microchip to every
potential illumination device.
 This would then combine two basic functionalities: illumination
and wireless data transmission
 This could solve the four essential problems that face us in wireless
communication these days
 In the future data for laptops, smartphones could be transmitted
through the light in a room.

27. videos
 https://www.ted.com/talks/harald_haas_wireless_dat
a_from_every_light_bulb?language=en
 https://www.ted.com/talks/harald_haas_a_breakthro
ugh_new_kind_of_wireless_internet?language=en