Introduction to li-fi technology

Introduction to Li-Fi Technology

O Iliad mehmandoostO Assistant Prof.:

Dr. Keshtgari

04/07/2023Introduction to Li-Fi technology 2

ObjectivesO What is li fi ??O Working of li-fi !!!O Construction of Li-Fi???O Comparison between Wi-Fi & Li-FiO How Li-Fi is different??O Applications of Li-Fi….O Advantages of Li-Fi….O Conclusion ….


What is Li-FiO Li-Fi is transmission of data through

illumination by taking the fiber out of fiber optics that varies in intensity faster than the human eye can follow.

O It is the fast and cheap Wireless communication system which is optical version of Wi-Fi.


Abstract of Li-Fi Technology

O Li-Fi can be thought of as a light-based Wi-Fi. That is, it uses light instead of radio waves to transmit information.

O 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.


HistoryO 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


on 12th July 2011. He used a table lamp with an LED bulb to transmit a video of blooming flowers that was then projected onto a screen behind him. 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 -- comparable to a fairly good UK broadband connection. Two months later he achieved 123Mbps.

Back in 2011 German scientists succeeded in creating an800Mbps (Megabits per second) capable wireless network by using nothing more than normal red, blue, green and yellw 0


LI FI- Light Fidelity

O Li-Fi is a VLC, visible light communication, technology developed by a team of scientists including Dr Gordon Povey, Prof. Harald Haas and Dr Mostafa Afgani at the University of Edinburgh.


O Li-Fi is now part of the Visible Light Communications (VLC) PAN IEEE 802.15.7 standard. “Li-Fi is typically implemented using white LED light bulbs. These devices are normally used for illumination by applying a constant current through the LED


O 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.


O 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. All one has to do is to vary the rate at which the LED’s flicker depending upon the data we want to encode. Further enhancements can be made in this method, like using an array of LEDs for parallel data transmission, or using mixtures of red, green and blue LEDs to alter the light’s frequency with each frequency encoding a different data channel. Such advancements promise a theoretical speed of 10 Gbps – meaning one can download a full high-definition film in just 30 seconds.


OThis technology uses a part of the electromagnetic spectrum that is still not greatly utilized- The Visible 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. Moreover 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.


Working of Li-FiO Its working is much simply explained as

follows:O If the LED is on, the digital 1 is transmitted.O And if it is off, the digital 0 is transmittedO 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 1s and 0s



Construction of Li-Fi…

Li-Fi product consists of 4 primary sub-assembliesOBulbORF power amplifier circuit(PA)OPrinted Circuit Board(PCB)OEnclosure


O The PCB controls the electrical inputs and outputs of the lamp and houses the microcontroller used to manage different lamp functions.

O An RF (radio-frequency) signal is generated by the solid-state PA and is guided into an electric field about the bulb.

Construction of Li-Fi…


O 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.

O All of these subassemblies are contained in an aluminum enclosure



Comparison between Li-Fi & Wi-Fi…

OWi-Fi is great for general wireless coverage within buildings, and Li-Fi is ideal for high density wireless data coverage in confined area and for releiving radio interference issues, so the two technologies can be considered complimentary.



How Li-Fi is diferent?

OLi-Fi technology is based on LEDs for the transfer of data

OThe transfer of data can be with the help of all kind of light i.e Light may be invisible, Ultraviolet or visible part of spectrum


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Capacity• Radiowaves• Cost and expense• Less Bandwidth compared to other spectrumsInsufficient

spectrum for increasing dataEfficiency• Millions of base stations consume huge amount of energy for:

– Transmitting the radio waves– To cool the base staions cabins

• 5% efficiencyAvailability• Available within the range of Base staions• Limited availability• Unavailabe in aircraftsSecurity• Less secure(passes through the walls)


Giga shower Giga MIMO

For giga-speed technologies, the Li-Fi Consortium defined GigaShower, GigaSpot and GigaMIMO models


O GigaShower and Giga-MIMO are the other models for in-house communication. There a transmitter or receiver is mounted into the ceiling connected to, for example, a media server

O GigaShower provides unidirectional data services via several channels to multiple users with gigabit-class com-munication speed over several metres. This is like watching TV channels or listening to different radio stations where no uplink channel is needed. In case GigaShower is used to sell books, music or movies, the connected media server can be accessed via Wi-Fi to process payment via a mobile device. GigaSpot and GigaMIMO are optical wireless single- and multi-channel HotSpot solutions offering bidirectional gigabit-class communication in a room, hall or shopping mall for example.


Applications of Li-Fi:

Some of the applications of Li-Fi are given below:O Medical fieldO AirlinesO Power plantsO Military operationsO Under sea water


Uses on applications

OUsed for modern medical instrumentsOLight is inherently safe and can be used

in places where radio frequency communication is often deemed problematic, such as in aircraft cabins or hospitals


AirlinesWhenever we travel through airways we face the problem in communication media ,because the whole airways communication are performed on the basis of radio waves. To overcomes this drawback on radioways , li-fi is introduced.


ON OCEAN BEDS

OLi-Fi can even wok underwater were Wi-Fi fails completely, thereby throwing open endless opportunities for military/navigation operations.


There are millions of street lamps deployed around the world.

O Each of these street lamps could be a free access point.



Limitations or challenges

O light can't pass through objectsO Interferences from external light sources like

sun light, normal bulbs, and opaque materials in the path of transmission will cause interruption in the communication.

O High installation cost of the VLC systemsO A major challenge facing Li-Fi is how the

receiving device will transmit back to transmitter.


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Introduction to li-fi technology