1. Li-Fi is a wireless optical networking technology that uses light-emitting diodes (LEDs) for data transmission. It can provide much higher speeds than Wi-Fi and has potential applications in areas where radio frequencies are regulated.
2. Li-Fi works by varying the intensity of light from an LED to transmit digital data. Researchers have achieved speeds over 500 Mbps in the lab. Potential advantages include abundant bandwidth and more secure localized transmission.
3. Key applications of Li-Fi include use in medical facilities, aircraft, and power plants where radio frequencies are restricted but high-speed connectivity is still needed. When combined with solid-state lighting infrastructure, Li-Fi could provide a cheaper alternative to
Today’s majority of data technique uses Radio Spectrum. But the major drawback of data
technique using radio spectrum is that it is very congested and the demand for wireless data
double each year. Every one, it seems want to use wireless data but the capacity is drying up.
Light –Fidelity is the transmission of data through illumination .It comprises of sending data
through a Light Emitting Diode which varies in intensity faster than human eye can follow .It
uses the fact that light travels at a such a high speed which is faster than human eye to catch.
Therefore when we vary the intensity of light emitting source it become impossible for the
humans to catch that sensation. It leads to very high speed data transmission, which is for
superior to current technologies.
Li-fi is transmission of data through illumination by taking the fiber out of fiber optics by sending data through a LED light bulb that varies in intensity faster than the human eye can follow. Li-Fi is a wireless optical networking technology that uses light-emitting diodes (LEDs) for data transmission.
Li-Fi is designed to use LED light bulbs similar to those currently in use in many energy-conscious homes and offices. However, LiFi bulbs are outfitted with a chip that modulates the light imperceptibly for optical data transmission. LiFi data is transmitted by the LED bulbs and received by photoreceptors.
Today’s majority of data technique uses Radio Spectrum. But the major drawback of data
technique using radio spectrum is that it is very congested and the demand for wireless data
double each year. Every one, it seems want to use wireless data but the capacity is drying up.
Light –Fidelity is the transmission of data through illumination .It comprises of sending data
through a Light Emitting Diode which varies in intensity faster than human eye can follow .It
uses the fact that light travels at a such a high speed which is faster than human eye to catch.
Therefore when we vary the intensity of light emitting source it become impossible for the
humans to catch that sensation. It leads to very high speed data transmission, which is for
superior to current technologies.
Li-fi is transmission of data through illumination by taking the fiber out of fiber optics by sending data through a LED light bulb that varies in intensity faster than the human eye can follow. Li-Fi is a wireless optical networking technology that uses light-emitting diodes (LEDs) for data transmission.
Li-Fi is designed to use LED light bulbs similar to those currently in use in many energy-conscious homes and offices. However, LiFi bulbs are outfitted with a chip that modulates the light imperceptibly for optical data transmission. LiFi data is transmitted by the LED bulbs and received by photoreceptors.
W
hether you’re using wireless internet in a coffee shop,stealing it from the guy next door, or competing for bandwidth at a conference, you have probably gotten frustrated at the slow speeds you face when more than one device is tapped into the network. As more and more people and their manydevices access wireless internet, clogged airwaves are going tomake it.
One German physicist, Harald Haas has come up with asolution he calls “data through illumination” –taking the fibberout of fiber optic by sending data through an LED light bulbthat varies in intensity faster than the human eye can follow.It’s the same idea band behind infrared remote controls but farmore powerful.
Haas says his invention, which he calls D-Light,can produce data rates faster than 10 megabits persecond, which is speedier than your average broadbandconnection. He envisions a future where data for laptops,smart phones, and tablets is transmitted through the light in aroom. And security would be snap – if you can’t see the light,you can’t access the data.
Li-Fi is typically implemented using white LED light bulbs at the downlink transmitter. These devices are normally used for illumination only by applying a constant current. However, by fast and subtle variations of the current, the optical output can be made to vary at extremely high speeds. This very property of optical current is used in Li-Fi setup.The operational procedure is very simple-,data from the internet and local network is used to modulate the intensity of the LED light source if any undetectable to the human eye. The photo detector picks up signal, which is converted back into a data stream and sent to the client.
The client can communicate through its own LED output or over the existing network. An overhead lamp fitted with an LED with signal-processing technology streams data embedded in its beam at ultra-high speeds to the photo-detector. A receiver dongle then converts the tiny changes in amplitude into an electrical signal, which is then converted back into a data stream and transmitted to a computer or mobile device.
At the heart of this technology, a new generation of high-brightness light-emitting diodes. Very simply, if the LED is ON, user can transmit a digital string of 1, if it’s OFF then user can transmit a string of 0. It can be switched ON and OFF very quickly, which gives instant opportunity for transmitting data. It is possible to encode data in the light by varying the rate at which the LEDs flicker ON and OFF to pass different strings of 1s and 0s. The modulation is so fast that the human eye doesn’t notice. There are over 14 billion light bulbs used across the world, which needs to be replaced with LEDs ones that transmit data.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Lifi(Light fidelity)-Efficient use of visible spectruminventionjournals
ABSTRACT : LEDs are beginning to be used in every home and office which makes LED’s light ideal for ubiquitous data transmitter This means that everywhere where LEDs are used, lighting bulbs can bring not only the light but wireless connection at the same time. With increasing demand for wireless data, lack of radio spectrum and issues with hazardous electromagnetic pollution, LiFi is a new wireless communication technology which enables a wireless data transmission through LED light. LiFi appears as a new greener, healthier and cheaper alternative to WiFi. Li-Fi is the emerging area of technology is also known as Visible Light Commu-nications (VLC) .Moreover LiFi makes possible to have a wireless Internet in specific environments (hospitals, airplanes etc.) where WiFi is not allowed due to interferences or security considerations.
Light Fidelity (Li-Fi) is a bidirectional, high speed , fully networked wireless communication technology similar to Wi-Fi. Li-Fi was first put forward by Professor Harald Haas,University of Edinburgh, during a TED Talk in 2011. Li-Fi 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 network), or even a replacement in contexts of data broadcasting. It is so far measured to be about 100 times faster than some Wi-Fi implementations, reaching speeds of 224 gigabits per second.
In this technology, light is passed through transmission channel as it is the fastest medium. It overcomes the defect of WI-FI as well. Transmission of data takes place through illumination. Using this, we can connect to several devices under a single LED light.
Li-Fi stand for ―light fidelity‖, it is a wireless optical networking technology that uses light emitting diodes (LEDs) for data transmission. Li-Fi is different from Wi-Fi that transmits data by using the spectrum of visible light.
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.
W
hether you’re using wireless internet in a coffee shop,stealing it from the guy next door, or competing for bandwidth at a conference, you have probably gotten frustrated at the slow speeds you face when more than one device is tapped into the network. As more and more people and their manydevices access wireless internet, clogged airwaves are going tomake it.
One German physicist, Harald Haas has come up with asolution he calls “data through illumination” –taking the fibberout of fiber optic by sending data through an LED light bulbthat varies in intensity faster than the human eye can follow.It’s the same idea band behind infrared remote controls but farmore powerful.
Haas says his invention, which he calls D-Light,can produce data rates faster than 10 megabits persecond, which is speedier than your average broadbandconnection. He envisions a future where data for laptops,smart phones, and tablets is transmitted through the light in aroom. And security would be snap – if you can’t see the light,you can’t access the data.
Li-Fi is typically implemented using white LED light bulbs at the downlink transmitter. These devices are normally used for illumination only by applying a constant current. However, by fast and subtle variations of the current, the optical output can be made to vary at extremely high speeds. This very property of optical current is used in Li-Fi setup.The operational procedure is very simple-,data from the internet and local network is used to modulate the intensity of the LED light source if any undetectable to the human eye. The photo detector picks up signal, which is converted back into a data stream and sent to the client.
The client can communicate through its own LED output or over the existing network. An overhead lamp fitted with an LED with signal-processing technology streams data embedded in its beam at ultra-high speeds to the photo-detector. A receiver dongle then converts the tiny changes in amplitude into an electrical signal, which is then converted back into a data stream and transmitted to a computer or mobile device.
At the heart of this technology, a new generation of high-brightness light-emitting diodes. Very simply, if the LED is ON, user can transmit a digital string of 1, if it’s OFF then user can transmit a string of 0. It can be switched ON and OFF very quickly, which gives instant opportunity for transmitting data. It is possible to encode data in the light by varying the rate at which the LEDs flicker ON and OFF to pass different strings of 1s and 0s. The modulation is so fast that the human eye doesn’t notice. There are over 14 billion light bulbs used across the world, which needs to be replaced with LEDs ones that transmit data.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Lifi(Light fidelity)-Efficient use of visible spectruminventionjournals
ABSTRACT : LEDs are beginning to be used in every home and office which makes LED’s light ideal for ubiquitous data transmitter This means that everywhere where LEDs are used, lighting bulbs can bring not only the light but wireless connection at the same time. With increasing demand for wireless data, lack of radio spectrum and issues with hazardous electromagnetic pollution, LiFi is a new wireless communication technology which enables a wireless data transmission through LED light. LiFi appears as a new greener, healthier and cheaper alternative to WiFi. Li-Fi is the emerging area of technology is also known as Visible Light Commu-nications (VLC) .Moreover LiFi makes possible to have a wireless Internet in specific environments (hospitals, airplanes etc.) where WiFi is not allowed due to interferences or security considerations.
Light Fidelity (Li-Fi) is a bidirectional, high speed , fully networked wireless communication technology similar to Wi-Fi. Li-Fi was first put forward by Professor Harald Haas,University of Edinburgh, during a TED Talk in 2011. Li-Fi 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 network), or even a replacement in contexts of data broadcasting. It is so far measured to be about 100 times faster than some Wi-Fi implementations, reaching speeds of 224 gigabits per second.
In this technology, light is passed through transmission channel as it is the fastest medium. It overcomes the defect of WI-FI as well. Transmission of data takes place through illumination. Using this, we can connect to several devices under a single LED light.
Li-Fi stand for ―light fidelity‖, it is a wireless optical networking technology that uses light emitting diodes (LEDs) for data transmission. Li-Fi is different from Wi-Fi that transmits data by using the spectrum of visible light.
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.
An Automatic Car Engine Startup and Brake Oil Monitoring Using SensorsIJRES Journal
The primary concern of “An Automatic Car Engine Startup and Brake Oil Monitoring Using Sensors” is to monitor the level of brake oil and to monitor the exact amount of engine fuel in digital form. It also shows the importance of unimodal biometric in order to identify or to verify a person that wants to start the engine of the car. A fingerprint sensor is placed on the car’s door and one in the dashboard to start the engine. If the person’s fingerprint matches then he can get into the car and start the engine.
Automatic irrigation using multiparameter monitoring abstractSiddappa Dollin
This is an abstract for the IEEE based ECE Project-Automatic Irrigation Using Multi-parameter Monitoring. It is one of the IEEE based project which can be implemented in real time and has advantages especially for Farmers. This is an abstract of the Project, you can find the Report from "Automatic Irrigation Using Multi-Parameter Monitoring_REPORT"
You can get the basic theme of an emerging communication technology named "LiFi" which will overcome the drawbacks of WiFi by a good margin!
(For watching the GIF's use Slideshow)
INTRODUCTION
HISTORY
PRESENT SCENARIO
ISSUES REGARDING RADIO SPECTRUM
VISIBLE LIGHT SPECTRUM
HOW LIFI WORKS
CONSTRUCTION OF LIFI
COMPARISON OF LIFI WITH WIFI
APPLICATIONS
LIMITATIONS
CONCLUSION
REFERENCES
lifi technology light feadility animated presentationSirod Deo
Li-fi basically known as “LIGHT FEDILITY” is an outcome of twenty first century. The basic ideology behind this technology is that the data can be transmitted through LED light whose intensity varies even faster than the human eye. As the transmission of the data takes place through the light emitting diodes (LED’s) the amount is comparatively small .In modern times, it is called as the optimized version of WI-FI .The advantageous thing is the wireless communication which decreases the cost enormously. HARALD HASS, who is considered to be the father of Li-fi from university of Edinburgh, UK says that the heart of this technology lies in the intensity and the potential of the light emitting diodes. The major reason which lead the modern man through this invention is that the confinement of Wi-Fi to comparatively small distance. As there are more and more devices coming up day-by-day the signals are being clogged up due to heavy traffic, there arised a need for an error free transmission technology. And the solution to this problem was the Li-fi technology..
Li-Fi stands for Light-Fidelity. Li-Fi is transmission of data using visible light by sending data through an LED light bulb that varies in intensity faster than the human eye can follow. If the LED is on, the photo detector registers a binary one; otherwise it‟s a binary zero. The idea of Li-Fi was introduced by a German physicist, Harald Hass, which he also referred to as “Data
through Illumination”. The term Li-Fi was first used by Haas in his TED Global talk on Visible Light Communication. According to Hass, the light, which he referred to as „DLight‟, can be used to produce data rates higher than 1 Giga bits per second which is much faster than our average broadband connection.
This Project discusses the implementation of the most basic Li-Fi based system to
transmit Sound signal from one device to another through visible light. The purpose is to demonstrate only the working of the simplest model of Li-Fi with no major consideration about the data transfer speed. This model will demonstrate how the notion of one-way communication via visible light works, in which Light emitting diodes (LEDs) are employed as the light sources or Transmitter antennas. the sound is transferred by light and is detected at the receiver without fading.
Li-Fi is a wireless optical networking technology that uses light-emitting diodes (LEDs) for data transmission.Li-Fi is designed to use LED light bulbs similar to those currently in use in many energy-conscious homes and offices.
A presention on LIFI technology..
Use MS Office 13 to view the original fonts and pics used within(as they are not supported in the previous versions..)
Smart phones, tablets, and the rise of the Internet of Things are driving an insatiable demand for wireless capacity. This demand requires networking and Internet infrastructures to evolve to meet the needs of current and future multimedia applications. Wireless HetNets will play an important role toward the goal of using a diverse spectrum to provide high quality-of-service, especially in indoor environments where most data are consumed. An additional tier in the wireless HetNets concept is envisioned using indoor gigabit small-cells to offer additional wireless capacity where it is needed the most. The use of light as a new mobile access medium is considered promising. In this article, we describe the general characteristics of WiFi and VLC (or LiFi) and demonstrate a practical framework for both technologies to coexist. We explore the existing research activity in this area and articulate current and future research challenges based on our experience in building a proof-of-concept prototype VLC HetNet.
This paper attempts to clarify the difference between visible light communication (VLC) and Light-Fidelity (LiFi). In particular, it will show how LiFi takes VLC further by using light emitting diodes (LEDs) to realise fully networked wireless systems. Synergies are harnessed as luminaries become LiFi attocells resulting in enhanced wireless capacity providing the necessary connectivity to realise the Internet-of-Things (IoT), and contributing to the key performance indicators for the 5th generation of cellular systems (5G) and beyond
Whether you’re using wireless internet in a coffee shop, stealing it from the guy next door, or competing for
bandwidth at a conference, you’ve probably gotten frustrated at the slow speeds you face when more than one device is
tapped into the network. As more and more people and their many devices access wireless internet, clogged airwaves
are going to make it increasingly difficult to latch onto a reliable signal. But radio waves are just one part of the
spectrum that can carry our data. What if we could use other waves to surf the internet? One German physicist,DR.
Harald Haas, has come up with a solution he calls “Data Through Illumination”—taking the fiber out of fiber optics by
sending data through an LED light bulb that varies in intensity faster than the human eye can follow. It’s the same idea
behind infrared remote controls, but far more powerful. Haas says his invention, which he calls D-Light, can produce
data rates faster than 10 megabits per second, which is speedier than your average broadband connection. He envisions a
future where data for laptops, smartphones, and tablets is transmitted through the light in a room. And security would be
a snap—if you can’t see the light, you can’t access the data. Li-Fi is a VLC, visible light communication, technology
developed by a team of scientists
Cosmetic shop management system project report.pdfKamal Acharya
Buying new cosmetic products is difficult. It can even be scary for those who have sensitive skin and are prone to skin trouble. The information needed to alleviate this problem is on the back of each product, but it's thought to interpret those ingredient lists unless you have a background in chemistry.
Instead of buying and hoping for the best, we can use data science to help us predict which products may be good fits for us. It includes various function programs to do the above mentioned tasks.
Data file handling has been effectively used in the program.
The automated cosmetic shop management system should deal with the automation of general workflow and administration process of the shop. The main processes of the system focus on customer's request where the system is able to search the most appropriate products and deliver it to the customers. It should help the employees to quickly identify the list of cosmetic product that have reached the minimum quantity and also keep a track of expired date for each cosmetic product. It should help the employees to find the rack number in which the product is placed.It is also Faster and more efficient way.
Saudi Arabia stands as a titan in the global energy landscape, renowned for its abundant oil and gas resources. It's the largest exporter of petroleum and holds some of the world's most significant reserves. Let's delve into the top 10 oil and gas projects shaping Saudi Arabia's energy future in 2024.
Vaccine management system project report documentation..pdfKamal Acharya
The Division of Vaccine and Immunization is facing increasing difficulty monitoring vaccines and other commodities distribution once they have been distributed from the national stores. With the introduction of new vaccines, more challenges have been anticipated with this additions posing serious threat to the already over strained vaccine supply chain system in Kenya.
Immunizing Image Classifiers Against Localized Adversary Attacksgerogepatton
This paper addresses the vulnerability of deep learning models, particularly convolutional neural networks
(CNN)s, to adversarial attacks and presents a proactive training technique designed to counter them. We
introduce a novel volumization algorithm, which transforms 2D images into 3D volumetric representations.
When combined with 3D convolution and deep curriculum learning optimization (CLO), itsignificantly improves
the immunity of models against localized universal attacks by up to 40%. We evaluate our proposed approach
using contemporary CNN architectures and the modified Canadian Institute for Advanced Research (CIFAR-10
and CIFAR-100) and ImageNet Large Scale Visual Recognition Challenge (ILSVRC12) datasets, showcasing
accuracy improvements over previous techniques. The results indicate that the combination of the volumetric
input and curriculum learning holds significant promise for mitigating adversarial attacks without necessitating
adversary training.
Water scarcity is the lack of fresh water resources to meet the standard water demand. There are two type of water scarcity. One is physical. The other is economic water scarcity.
Student information management system project report ii.pdfKamal Acharya
Our project explains about the student management. This project mainly explains the various actions related to student details. This project shows some ease in adding, editing and deleting the student details. It also provides a less time consuming process for viewing, adding, editing and deleting the marks of the students.
About
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
Technical Specifications
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
Key Features
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface
• Compatible with MAFI CCR system
• Copatiable with IDM8000 CCR
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
Application
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
TECHNICAL TRAINING MANUAL GENERAL FAMILIARIZATION COURSEDuvanRamosGarzon1
AIRCRAFT GENERAL
The Single Aisle is the most advanced family aircraft in service today, with fly-by-wire flight controls.
The A318, A319, A320 and A321 are twin-engine subsonic medium range aircraft.
The family offers a choice of engines
Explore the innovative world of trenchless pipe repair with our comprehensive guide, "The Benefits and Techniques of Trenchless Pipe Repair." This document delves into the modern methods of repairing underground pipes without the need for extensive excavation, highlighting the numerous advantages and the latest techniques used in the industry.
Learn about the cost savings, reduced environmental impact, and minimal disruption associated with trenchless technology. Discover detailed explanations of popular techniques such as pipe bursting, cured-in-place pipe (CIPP) lining, and directional drilling. Understand how these methods can be applied to various types of infrastructure, from residential plumbing to large-scale municipal systems.
Ideal for homeowners, contractors, engineers, and anyone interested in modern plumbing solutions, this guide provides valuable insights into why trenchless pipe repair is becoming the preferred choice for pipe rehabilitation. Stay informed about the latest advancements and best practices in the field.
Courier management system project report.pdfKamal Acharya
It is now-a-days very important for the people to send or receive articles like imported furniture, electronic items, gifts, business goods and the like. People depend vastly on different transport systems which mostly use the manual way of receiving and delivering the articles. There is no way to track the articles till they are received and there is no way to let the customer know what happened in transit, once he booked some articles. In such a situation, we need a system which completely computerizes the cargo activities including time to time tracking of the articles sent. This need is fulfilled by Courier Management System software which is online software for the cargo management people that enables them to receive the goods from a source and send them to a required destination and track their status from time to time.
1. 1
Li-Fi (Light Fidelity) Technology
1. INTRODUCTION
LiFi is transmission of data through illumination by taking the fiber out of fiber optics
by sending data through a LED light bulb that varies in intensity faster than the human eye
can follow. Li-Fi is the term some have used to label the fast and cheap wireless
communication system, which is the optical version of Wi-Fi. The term was first used in this
context by Harald Haas in his TED Global talk on Visible Light Communication. “At the
heart of this technology is a new generation of high brightness light-emitting diodes”, says
Harald Haas from the University of Edinburgh, UK.
“Very simply, if the LED is on, you transmit a digital 1, if it’s off you transmit a
0,”Haas says, “They can be switched on and off very quickly, which gives nice opportunities
for transmitted data.”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.The LED intensity is modulated
so rapidly that human eye cannot notice, so the output appears constant. More sophisticated
techniques could dramatically increase VLC data rate. Terms at the University of Oxford and
the University of Edingburgh are focusing on parallel data transmission using array of LEDs,
where each LED transmits a different data stream. Other group are using mixtures of red,
green and blue LEDs to alter the light frequency encoding a different data channel. Li-Fi, as it
has been dubbed, has already achieved blisteringly high speed in the lab. Researchers at the
Heinrich Hertz Institute in Berlin, Germany, have reached data rates of over 500 megabytes
per second using a standard white-light LED. The technology was demonstrated at the 2012
Consumer Electronics Show in Las Vegas using a pair of Casio smart phones to exchange
data using light of varying intensity given off from their screens, detectable at a distance of
up to ten metres.
Light is inherently safe and can be used in places where radio frequency
communication is often deemed problematic, such as in aircraft cabins or hospitals. So visible
light communication not only has the potential to solve the problem of lack of spectrum
space, but can also enable novel application. The visible light spectrum is unused; it's not
regulated, and can be used for communication at very high speeds.
2. 2
Fig.1.1 Li-Fi environment
In October 2011 a number of companies and industry groups formed the Li-Fi
Consortium, to promote high-speed optical wireless systems and to overcome the limited
amount of radiobased wireless spectrum available by exploiting a completely different part of
the electromagnetic spectrum. The consortium believes it is possible to achieve more than 10
Gbps, theoretically allowing a high-definition film to be downloaded in 30 seconds.
2. HISTORY:
Professor Harald Haas, from the University of Edinburgh in the UK, is widely
recognised as the original founder of Li-Fi. He coined the term Li-Fi and is Chair of Mobile
Communications at the University of Edinburgh and co-founder of pureLiFi.
The general term visible light communication (VLC), includes any use of the visible light
portion of the electromagnetic spectrum to transmit information. The D-Light project at
Edinburgh's Institute for Digital Communications was funded from January 2010 to January
2012. Haas promoted this technology in his 2011TED Global talk and helped start a company
3. 3
to market it. PureLiFi, formerly pureVLC, is an original equipment manufacturer (OEM) firm
set up to commercialize Li-Fi products for integration with existing LED-lighting systems.
VLC technology was exhibited in 2012 using Li-Fi. By August 2013, data rates of over
1.6 Gbps were demonstrated over a single color LED. In September 2013, a press release said
that Li-Fi, or VLC systems in general, do not require line-of-sight conditions. The first Li-
Fi smartphone prototype was presented at the Consumer Electronics Show in Las Vegas from
January 7–10 in 2014. The phone uses Sun Partner’s Wysips CONNECT, a technique that
converts light waves into usable energy, making the phone capable of receiving and decoding
signals without drawing on its battery.
Li-Fi, or light fidelity, refers to 5G visible light communication systems using light
from light-emitting diodes (LEDs) as a medium to deliver networked, mobile, high-speed
communication in a similar manner as Wi-Fi. Li-Fi could lead to the Internet of Things,
which is everything electronic being connected to the internet, with the LED lights on the
electronics being used as internet access points.
3. WORKING TECHNOLOGY
This brilliant idea was first showcased by Harald Haas from University of Edinburgh,
UK, in his TED Global talk on VLC. He explained,” Very simple, if the LED is on, you
transmit a digital 1, if it’s off you transmit a 0. The LEDs can be switched on and off very
quickly, which gives nice opportunities for transmitting data.” So what you require at all are
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. 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 you can download a full high-definition film in just 30 seconds. Simply awesome!
But blazingly fast data rates and depleting bandwidths worldwide are not the only reasons
that give this technology an upper hand. Since Li-Fi uses just the light, it can be used safely
in aircrafts and hospitals that are prone to interference from radio waves. This can even work
underwater where Wi-Fi fails completely, thereby throwing open endless opportunities for
military operations.
4. 4
Imagine only needing to hover under a street lamp to get public internet access, or
downloading a movie from the lamp on your desk. Radio waves are replaced by light waves
in a new method of data transmission which is being called Li-Fi.Light-emitting diodes can
be switched on and off faster than the human eye can detect, causing the light source to
appear to be on continuously. A flickering light can be incredibly annoying, but has turned
out to have its upside, being precisely what makes it possible to use light for wireless data
transmission. Light-emitting diodes (commonly referred to as LEDs and found in traffic and
street lights, car brake lights, remote control units and countless other applications) can be
switched on and off faster than the human eye can detect, causing the light source to appear
to be on continuously, even though it is in fact 'flickering'. This invisible on-off activity
enables a kind of data transmission using binary codes: switching on an LED is a logical '1',
switching it off is a logical '0'. Information can therefore be encoded in the light by varying
the rate at which the LEDs flicker on and off to give different strings of 1s and 0s.
Fig. 3.1 Data Transmission Using An Led
5. 5
4. Four Issues with Radio Waves:
1. Capacity:
We transmit wireless data through radio waves.
Radio waves are limited, scar and expensive.
We only have a certain range of it.
With the advent of the new generation technologies as of likes of 2.5G, 3G, 4G
and so on we are running out of spectrum.
2. Efficiency:
There are 1.4 million cellular radio base stations.
They consume massive amount of energy.
Most of this energy is not used for transmission but for cooling down the base
stations.
Efficiency of such a base station is only 5% and that raise a very big problem.
3. Availability:
We have to switch off our mobiles in aeroplanes.
It is not advisable to use mobiles at places like petrochemical plants and petrol
pumps.
Availability of radio waves causes another concern.
4. Security:
Radio waves penetrate through walls.
They can be intercepted.
If someone has knowledge and bad intentions then he may misuse it.
Alternative to Radio waves in Electromagnetic Spectrum:
So there are four major concerns i.e., capacity, efficiency, availability, security related with
Radio waves. But on the other hand we have 40 billions of light box already installed and
light is part of electromagnetic spectrum. So let’s look up at this in context of EM spectrum.
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Figure 4.1 Electro-Magnetic Spectrum
Gamma rays are simply very dangerous and thus can’t be used for our purpose of
communication.
X-rays are good in hospital and can’t be used either.
Ultra-violet rays are sometimes good for our skin but for long duration it is
dangerous.
Infra-red rays are bad for our eyes and are therefore used at low power levels.
We have already seen shortcomings of radio waves.
So we are left with only Visible light spectrum.
Visible light communication (VLC)-“A potential solution to the global
wireless spectrum shortage”
LiFi (Light Fidelity) is a fast and cheap optical version of Wi-Fi, the technology of
which is based on Visible Light Communication (VLC).VLC is a data communication
medium, which uses visible light between 400 THz (780 nm) and 800 THz (375 nm) as
optical carrier for data transmission and illumination. It uses fast pulses of light to transmit
information wirelessly. The main components of this communication system are 1) a high
brightness white LED, Which acts as a communication source and 2) a silicon photodiode
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which shows good response to visible wavelength region serving as the receiving element?
LED can be switched on and off to generate digital strings of 1s and 0s. Data can be encoded
in the light to generate a new data stream by varying the flickering rate of the LED. To be
clearer, by modulating the LED light with the data signal, the LED illumination can be used
as a communication source. As the flickering rate is so fast, the LED output appears constant
to the human eye. A data rate of greater than 100 Mbps is possible by using high speed LEDs
with appropriate multiplexing techniques. VLC. data rate can be increased by parallel data
transmission using LED arrays where each LED transmits a different data stream. There are
reasons to prefer LED as the light source in VLC while a lot of other illumination devices
like fluorescent lamp, incandescent bulb etc. are available.
5. COMPARISION BETWEEN Li-Fi & Wi-Fi
LI-FI is a term of one used to describe visible light communication technology
applied to high speed wireless communication. It acquired this name due to the similarity to
WI-FI, only using light instead of radio.WI-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
relieving radio interference issues, so the two technologies can be considered complimentary.
Table 1.Comparison between current and future wireless technology
The table also contains the current wireless technologies that can be used for transferring
data between devices today, i.e. Wi-Fi, Bluetooth and IrDA. Only Wi-Fi currently offers very
high data rates. The IEEE 802.11.n in most implementations provides up to 150Mbit/s (in
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theory the standard can go to 600Mbit/s) although in practice you receive considerably less
than this. Note that one out of three of these is an optical technology.
6. How it is different?
Li-Fi technology is based on LEDs for the transfer of data. The transfer of the data
can be with the help of all kinds of light, no matter the part of the spectrum that they belong.
That is, the light can belong to the invisible, ultraviolet or the visible part of the spectrum.
Also, the speed of the internet is incredibly high and you can download movies, games, music
etc in just a few minutes with the help of this technology. Also, the technology removes
limitations that have been put on the user by the Wi-Fi. You no more need to be in a region
that is Wi-Fi enabled to have access to the internet. You can simply stand under any form of
light and surf the internet as the connection is made in case of any light presence. There
cannot be anything better than this technology.
Fig 6.1.Working and advantages
To further get a grasp of Li-Fi consider an IR remote. It sends a single data stream of bits at
the rate of 10,000-20,000 bps. Now replace the IR LED with a Light Box containing a large
LED array.
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Figure 6.2. How Data Transmission Works
(i) High speed
The research, known as the ultra-parallel visible light communications project, is a joint
venture between the universities of Edinburgh, St Andrews, Strathclyde, Oxford, and
Cambridge, and funded by the Engineering and Physical Sciences Research Council.
The tiny micro-LED bulbs, developed by the University of Strathclyde, Glasgow, allow
streams of light to be beamed in parallel, each multiplying the amount of data that can be
transmitted at any one time.
"If you think of a shower head separating water out into parallel streams, that's how we can
make light behave," said Prof Harald Haas, an expert in optical wireless communications at
the University of Edinburgh and one of the project leaders.
Using a digital modulation technique called Orthogonal Frequency Divisional Multiplexing
(OFDM), researchers enabled micro-LED light bulbs to handle millions of changes in light
intensity per second, effectively behaving like an extremely fast on/off switch.
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This allows large chunks of binary data - a series of ones and zeros - to be transmitted at high
speed.
Earlier this year, Germany's Fraunhofer Heinrich Hertz Institute claimed that data rates of up
to 1Gbit/s per LED light frequency were possible in laboratory conditions. And this month,
Chinese scientists reportedly developed a microchipped LED bulb that can produce data
speeds of up to 150 megabits per second (Mbps), with one bulb providing internet
connectivity for four computers.
(ii) 'Light fidelity'
Prof Harald Haas has been in the forefront of "li-fi" research for the last 10 years
In 2011, Prof Haas demonstrated how an LED bulb equipped with signal processing
technology could stream a high-definition video to a computer.
He coined the term "light fidelity" or li-fi - also known as visual light communications (VLC)
- and set up a private company, PureVLC, to exploit the technology.
a) Li-fi promises to be cheaper and more energy-efficient than existing wireless radio
systems given the ubiquity of LED bulbs and the fact that lighting infrastructure is
already in place.
b) Visible light is part of the electromagnetic spectrum and its bandwidth is 10,000 times
bigger than the radio frequency spectrum used by existing communication systems,
affording vastly greater capacity.
c) Another advantage, Prof Haas argues, is that evenly spaced LED transmitters could
provide much more localised and consistent internet connectivity throughout
buildings.
d) Li-Fi also has the advantage of being able to be used in electromagnetic sensitive
areas such as in aircraft cabins, hospitals and nuclear power plants without
causing electromagnetic interference. Both Wi-Fi and Li-Fi transmit data over
the electromagnetic spectrum, but whereas Wi-Fi utilises radio waves, Li-Fi uses
visible light.
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e) While the US Federal Communications Commission has warned of a potential
spectrum crisis because Wi-Fi is close to full capacity, Li-Fi has almost no limitations
on capacity. The visible light spectrum is 10,000 times larger than the entire radio
frequency spectrum. Researchers have reached data rates of over 10 Gbps, which is
more than 250 times faster than superfast broadband. Li-Fi is expected to be ten times
cheaper and more environmentally friendly than Wi-Fi. Short range, low reliability
and high installation costs are the potential downsides.
f) Prof Haas also believes light's inability to penetrate walls makes VLC technology
potentially more secure than traditional wi-fi connectivity.
A one-watt LED light bulb would be enough to provide net connectivity to four computers,
researchers say. But there are no supporting video or photos showing the technology in
action.
7. APPLICATION OF LI-FI:-
a.) Medical - You Might Just Live Longer
For a long time, medical technology has lagged behind the rest of the wireless world.
Operating rooms do not allow Wi-Fi over radiation concerns, and there is also that whole lack
of dedicated spectrum. While Wi-Fi is in place in many hospitals, interference from cell
phones and computers can block signals from monitoring equipment. Li-Fi solves both
problems: After all, lights are allowed in operating rooms.
b.) Airlines:
Airline Wi-Fi. Ugh. Passengers will "soon" be offered a "high-speed like" connection
on some airlines. United is planning on speeds as high as 9.8 Mbps per plane. And at the
same price as checking a bag, I expect it. Li-Fi could easily introduce that sort of speed to
each seat's reading light. Now, that is just awesome, isn’t it?
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c.) Smarter Power Plants:
Wi-Fi and many other radiation types are bad for sensitive areas. Like those
surrounding power plants. But power plants need fast, inter-connected data systems to
monitor things like demand, grid integrity and (in nuclear plants) core temperature. Li-Fi
could offer safe, abundant connectivity for all areas of these sensitive locations.
d.) Undersea Awesomeness:
Underwater ROVs, those favorite toys of treasure seekers and James Cameron,
operate from large cables that supply their power and allow them to receive signals from their
pilots above. ROVs work great, except when the tether isn’t long enough to explore an area,
or when it gets stuck on something. If their wires were cut and replaced with light — say
from a submerged, high-powered lamp — then they would be much freer to explore. They
could also use their headlamps to communicate with each other, processing data
autonomously and referring findings periodically back to the surface, all the while obtaining
their next batch of orders.
e.) It Could Keep You Informed and Save Lives
Say there’s an earthquake in New York. The average New Yorker may not know what
the protocols are for those kinds of disasters. Until they pass under a street light, that is.
Remember, with Li-Fi, if there’s light, you’re online. Subway stations and tunnels, common
dead zones for most emergency communications, pose no obstruction. Plus, in times less
stressing cities could opt to provide cheap high-speed Web access to every street corner.
f.) USES IN VARIOUS AREAS
In traffic signals LiFi can be used which will communicate with the LED lights of the
cars and accident numbers can be decreased. Thousand and millions of street lamps can be
transferred to LiFi lamps to transfer data.
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g.) Genesis of LI-FI:
Harald Haas, a professor at the University of Edinburgh who began his research in the field in
2004, gave a debut demonstration of what he called a Li-Fi prototype at the TED Global
conference in Edinburgh 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 TED Global, Haas demonstrated a data rate of
transmission of around 10Mbps -- comparable to a fairly good UK broadband connection.
Two months later he achieved 123Mbps.
8. How LiFi Light Sources Work
LIFI lighting applications work better compared to conventional approaches. This technology
brief describes the general construction of LIFI lighting systems and the basic technology
building blocks behind their function.
LIFI CONSTRUCTION
The LIFI product consists of 4 primary sub-assemblies:
• Bulb
• RF power amplifier circuit (PA)
• Printed circuit board (PCB)
• Enclosure
The PCB controls the electrical inputs and outputs of the lamp and houses the microcontroller
used to manage different lamp functions. An 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. All of these subassemblies
are contained in an aluminum enclosure.
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FUNCTION OF THE BULB SUB-ASSEMBLY
At the heart of LIFI is the bulb sub-assembly where a sealed bulb is embedded in a
dielectric material. This design is more reliable than conventional light sources that insert
degradable electrodes into the bulb. The dielectric material serves two purposes; first as a
wave guide for the RF energy transmitted by the PA and second as an electric field
concentrator that focuses energy in the bulb. The energy from the electric field rapidly heats
the material in the bulb to a plasma state that emits light of high intensity and full spectrum.
The LIFI product consists of 4 primary sub-assemblies:
• Bulb
• RF power amplifier circuit (PA)
• Printed circuit board (PCB)
• Enclosure
The PCB controls the electrical inputs and outputs of the lamp and houses the micro-
controller used to manage different lamp functions.
The design and construction of the LIFI light source enable efficiency, long stable life, full
spectrum intensity that is digitally controlled and easy to use.
FIG 8.1 :- LI-FI HAS AN UPPERHAND DUE TO PARALLEL DATA TRANSMISSION
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9. Conclusion:
The possibilities are numerous and can be explored further. If his
technology can be put into practical use, every bulb can be used something like a Wi-Fi
hotspot to transmit wireless data and we will proceed toward the cleaner, greener, safer and
brighter future. The concept of Li-Fi is currently attracting a great deal of interest, not least
because it may offer a genuine and very efficient alternative to radio-based wireless. As a
growing number of people and their many devices access wireless internet, the airwaves are
becoming increasingly clogged, making it more and more difficult to get a reliable, high-
speed signal. This may solve issues such as the shortage of radio-frequency bandwidth and
also allow internet where traditional radio based wireless isn’t allowed such as aircraft or
hospitals. One of the shortcomings however is that it only work in direct line of sight.
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10. REFERENCES
1. http://en.wikipedia.org/wiki/Li-Fi
2. http://teleinfobd.blogspot.in/2012/01/what-is-lifi.html
3. technopits.blogspot.comtechnology.cgap.org/2012/01/11/a-lifi-world/
4. www.lificonsortium.org/
5. the-gadgeteer.com/2011/08/29/li-fi-internet-at-thespeed-of-light/
6. dvice.com/archives/2012/08/lifi-ten-ways-i.php
7. Will Li-Fi be the new Wi-Fi?, New Scientist, by Jamie Condliffe, dated 28 July 2011
8. http://www.digplanet.com/wiki/Li-Fi
9. “Visible-light communication: Tripping the light fantastic: A fast and cheap optical
version of Wi-Fi is coming”, Economist, dated 28Jan 2012.