2. ‘Heaven’s light is our guide’
RAJSHAHI UNIVERSITY OF ENGINEERING & TECHNOLOGY
Presented by:
Saad Mahmud(124004)
Afra Anjum Irina(124005)
Md.Ashfaqul Haque(124006)
ahqj
3. Contents:
What is lifi ?
Construction
Working principle
Why lifi
Implementation
Application
Limitations
Future appliance
Conclusion
ahqj
4. Lifi:
Light Fidelity (Li-Fi) is a bidirectional, high-speed and fully
networked wireless communication technology similar to Wi-Fi . It
is a form of visible light communication and a subset of optical
wireless communications (OWC) and could be a complement to RF
communication (Wi-Fi or cellular networks), or even a replacement
in contexts of data broadcasting . It was first introduced by Harald
Haas.
ahqj
5. Construction:
The main components of Li-Fi system are as follows:
a) a high brightness white LED which acts as transmission source.
b) a silicon photodiode with good response to visible light as the receiving
element.
The Li-Fi emitter system consists of 4 primary subassemblies:
a) Bulb
b) RF power amplifier circuit (PA)
c) Printed circuit board (PCB)
d) Enclosure
ahqj
6. The PCB controls the electrical inputs and outputs of the lamp and houses the
microcontroller used to manage different lamp functions.
A RF (radio-frequency) signal is generated by the solid-state PA and is guided into an
electric field about the bulb.
The high concentration of energy in the electric field vaporizes the contents of the bulb to a
plasma state at the bulb‘s center. This controlled plasma generates an intense source of
light.
ahqj
7. Working principle:
It is based on Visible Light Communication (VLC).
A new generation of high brightness light-emitting diodes forms the core part of light
fidelity technology. The logic is very simple. If the LED is on, a digital 1 is
transmitted. If the LED is off, a digital 0 is transmitted. These high brightness LEDs
can be switched on and off very quickly which gives us a very nice opportunities for
transmitting data through light.
There will be a photo detector registers a binary one when the LED is on and a
binary zero if the LED is off to build up a message.
ahqj
9. Why lifi ?
Previously we could send only one data stream at a time. But with this technology we
can transmit thousand of data stream in parallel with faster rate at a time. Its data
transmission rate is over 1 Gbps .( last achieved 10 Gbps )
For single data stream:
For multiple data stream:
ahqj
12. Various applications of lifi:
Hospital & Healthcare: Li-Fi emits no electromagnetic interference and so does not
interfere with medical instruments, nor is it interfered with by MRI scanners as its
frequency is in visible spectrum.
ahqj
13. Smart Lighting: Any private or public lighting including street lamps can be used to
provide Li-Fi hotspots and the same communications and sensor infrastructure can be
used to monitor and control lighting and data.
ahqj
14. Mobile Connectivity: Laptops, smart phones, tablets and other mobile devices can
interconnect directly using Li-Fi. Short range links give very high data rates and also
provides security.
ahqj
15. Vehicles & Transportation: LED headlights and tail-lights are being introduced.
Street lamps, signage and traffic signals are also moving to LED. This can be used for
vehicle-to-vehicle and vehicle-to-roadside communications. This can be applied for
road safety and traffic management.
ahqj
16. Underwater Communications: Due to strong signal absorption in water, RF use is
impractical. Acoustic waves have extremely low bandwidth and disturb marine life.
Li-Fi provides a solution for short-range communications. For remote operated
vehicle (ROV) wires can be replaced with light using lifi .
ahqj
18. Limitations of Lifi:
Nothing in this world is perfect and so does LIFI.
These signals cannot penetrate walls. So the person needs wired bulb in that room
also.
Only works if there is direct line of sight between source and receiver.
Even at day light we need to keep the lights on.
Used for broadcast and it is difficult to uplink.
Interferences from external light sources like sun, light, normal bulbs, opaque
materials.
ahqj
19. Future Appliance:
Finding the location of a person :
LiFi uses visible light and this property can be exploited in finding the location
of people. Suppose if a child is misplaced and he/she is wearing an earing which is
made of Led’s. this led can constantly communicate with the visible light available
and reveal the location of the child.
Navigation System :
Since visible light is present everywhere, we can create internal navigation
systems for the bigger areas to create automated machinery/ automatic navigation for
the visitors.
ahqj
20. Conclusion:
The concept of Li-Fi is attracting a lot of eye-balls because it offers a
genuine and very efficient alternative to radio based wireless. It has a bright chance to
replace the traditional Wi-Fi because as an ever increasing population is using
wireless internet, the airwaves are becoming increasingly clogged, making it more
and more difficult to get a reliable, high-speed signal. This concept promises to solve
issues such as the shortage of radio-frequency bandwidth and boot out the
disadvantages of Wi-Fi.
ahqj
