L I F ILight Fidelity

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‘Heaven’s light is our guide’

RAJSHAHI UNIVERSITY OF ENGINEERING & TECHNOLOGY

Presented by:

Saad Mahmud(124004)

Afra Anjum Irina(124005)

Md.Ashfaqul Haque(124006)

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Contents: What is lifi ? Construction Working principle Why lifi Implementation Application Limitations Future appliance Conclusion

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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.

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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

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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.

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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.

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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:

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Implementation of Lifi :

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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.

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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.

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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.

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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.

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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 .

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Airlines:

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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.

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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.

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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.

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Thanks to all.

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