High-speed wireless networking using visible light
SPIE Newsroom, 19 April 2013
White LEDs hold promise as a key enabler for future wireless networks based on optical attocells, offering significant improvements to indoor data coverage.
The advent of the first cellphones in the 1980s marked the beginning of commercial mobile communications. Now, only 30 years later, wireless connectivity has become a fundamental part of our everyday lives and is increasingly being regarded as an essential commodity like electricity, gas, and water. The technology's huge success means we are now facing an imminent shortage of radiofrequency (RF) spectrum. The amount of data sent through wireless networks is expected to increase 10-fold during the next four years.1 At the same time, there isn't enough new RF spectrum available to allocate. In addition, the spectral efficiency (the number of bits successfully transmitted per Hertz bandwidth) of wireless networks has become saturated, despite tremendous technological advancements in the last 10 years. The US Federal Communications Commission has therefore warned of a potential spectrum crisis.
Light fidelity (Li-Fi),2 the high-speed communication and networking variant of visible light communication (VLC),3 aims to unlock a vast amount of unused electromagnetic spectrum in the visible light region (see Figure 1). Li-Fi works as a signal transmitter with the off-the-shelf white LEDs typically used for solid-state lighting and as a signal receiver with a p-i-n photodiode or avalanche photodiode. This means that Li-Fi systems can illuminate a room and at the same time provide wireless data connectivity. Unlike laser diodes, the LEDs my colleagues and I studied produce incoherent light, which means the signal phase cannot be used for data communications. Therefore, the only way to encode data is to use intensity modulation and direct detection. This poses severe restrictions on the data rates we can achieve.
Li-Fi could be the future of the web
Could Li-Fi spark a communications revolution like Wi-Fi?
London Press Service, 16 April 2013
Multi-tasking micro-lights now being developed could initiate an amazing transformation for the future of communications.
Tiny light-emitting diode (LED) lights could deliver Wi-Fi-like internet communications, while simultaneously displaying information and providing illumination for homes, offices and many other locations.
Over the next four years, a consortium of universities in the United Kingdom will be developing this innovative technology to help unleash the full potential of “Li-Fi” - the transmission of internet communications using visible light rather than the radio waves and microwaves currently in use.
The project is being led by the University of Strathclyde, Scotland, with funding from the UK’s Engineering & Physical Sciences Research Council (EPSRC). Although the potential possibilities offered by Li-Fi are being explored all over the world, this EPSRC-funded consortium is pursuing a radical, distinctive vision that could deliver enormous benefits.
High-Speed Internet from the Ceiling Lamp
Fraunhofer Heinrich-Hertz Institut, 5 April 2013
In visible light communication, the Fraunhofer Heinrich Hertz Institute HHI has set a further milestone on the way to highspeed internet from the ceiling lamp. Development of novel components for data transmission over LEDs means that significantly higher bandwidth can now be used in real-time with data throughput rates of up to 3 Gbit/s being reached in laboratory experiments. The new components will be presented at FOE 2013.
The technology developed by HHI makes it possible to use standard off-the-shelf LED room lights for data transmission. Data rates of up to 800 Mbit/s were reached by this optical WLAN under laboratory conditions, while a complete real-time system exhibited at trade fairs reached data throughput of 500 Mbit/s. The newly developed patent protected components have now achieved a transmission rate in laboratory experiments of over 1 Gbit/s per single light frequency. As off-the-shelf LEDs mainly use three light frequencies or light colors, speeds of up to 3 Gbit/s are feasible.
LED data communication
Data Traveling by Light
Science Daily, 21 August 2011
Regular LEDs can be turned into optical WLAN with only a few additional components thanks to visible light communication (in short, VLC). The lights are then not just lighting up, they also transfer data. They send films in HD quality to your iPhone or laptop, with no loss in quality, quickly and safely.
Just imagine the following scenario: four people are comfortably ensconced in a room. Each one of them can watch a film from the Internet on his or her laptop, in HD quality. This is made possible thanks to optical WLAN. Light from the LEDs in the overhead lights serves as the transfer medium. For a long time, this was just a vision for the future. However, since scientists from the Fraunhofer Institute for Telecommunications, Heinrich Hertz Institute HHI in Berlin, Germany, have developed a new transfer technology for video data within the scope of the OMEGA project of the EU, its implementation in real life is getting markedly closer.
Will Li-Fi be the new Wi-Fi?
New Scientist, 28 July 2011
FLICKERING lights are annoying but they may have an upside. Visible light communication (VLC) uses rapid pulses of light to transmit information wirelessly. Now it may be ready to compete with conventional Wi-Fi.
"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 transmitting 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 eyes cannot notice, so the output appears constant.
Using Light to Send Data Across the Room
New York Times, 18 July 2011
After Wi-Fi, will there be… Li-Fi?
Researchers around the world are fine-tuning technologies that use standard lighting equipment to cheaply transmit high-speed data streams wirelessly, even while the equipment appears to be producing nothing more than normal illumination. Generally, the technologies rapidly and subtly fluctuate the intensity of light-emitting diodes, or LEDs, in a way that is imperceptible to the human eye.
Light reading: visible light communications
The Engineer, 14 February 2011
Advanced LED-based technology could revolutionise the way we send and receive data. Ellie Zolfagharifard reports.
The human desire for light was one of the reasons that caveman became engineer. From the very first camp fires to the oil-filled lamp and electric torch, man-made light has led the development of the modern world.
The objective has always been a simple one: to provide illumination in areas that the Sun can’t reach. We’ve been extremely successful in this, with more and more places on Earth touched by artificial light each day. The technology has showcased our best innovations and given us the ability to see things that would otherwise be hidden.
But what if light could do more than just illuminate? What if it could also send streams of data? Traffic lights, television sets, car headlights, billboards and lamps might all suddenly become far more important in our daily lives. We could receive maps from a street light, get news alerts from lamps and download music from electronic posters.
Ceiling lights in Minnesota send coded Internet data
The Washington Post, 27 December 2010
Flickering ceiling lights are usually a nuisance, but in city offices in St. Cloud, they will actually be a pathway to the Internet.
The lights will transmit data to specially equipped computers on desks below by flickering faster than the eye can see. Ultimately, the technique could ease wireless congestion by opening up new expressways for short-range communications.
The first few light fixtures built by LVX System, a local startup, will be installed Wednesday in six municipal buildings in this city of 66,000 in the snowy farm fields of central Minnesota.
New Energy-Saving Invention Uses Light to Connect With Internet
The Electrical Worker, March 2010
In the near future, hooking up to the Internet may be as simple as turning on the lights.
A new wireless data communication system, invented and patented by a D.C.-based company and licensed to Minnesota's LVX System, uses visible light instead of radio waves to transmit digital information, a development that could revolutionize online communications.
"We're talking faster speeds and more secure connections, all with reduced energy consumption," said LVX Lab Chief Executive Officer Mike Muggli.
Muggli was at the IBEW International Office in Washington, D.C. late last year to show off the company's new invention.
LED technology for lighting and data transfer
LED's used for lighting in home and office, and used for data transfer at the same time, used for wireless internet connection.
Visible light illuminates a new approach for wireless comms
EE Times, 6 July 2010 With preparations well under way for a societal shift to solid-state lighting based on high-output LEDs, a proverbial light bulb has appeared above the heads of some forward-looking engineers. Their proposal: Why not switch the LEDs on and off so fast the eye cannot tell, in order to use them to transmit data too? With enough advance work, every new LED light fixture could also be wired into the network backbone, accomplishing ubiquitous wireless communications to any device in a room without burdening the already crowded radio-frequency bands. Visible light communications (VLC) is being refined by industry, standards groups and well-funded government initiatives. And the stakes are enormous, since the traditional lighting market is measured in trillions of dollars and the transition to solid-state has already begun.
EE Times, 6 July 2010
With preparations well under way for a societal shift to solid-state lighting based on high-output LEDs, a proverbial light bulb has appeared above the heads of some forward-looking engineers. Their proposal: Why not switch the LEDs on and off so fast the eye cannot tell, in order to use them to transmit data too?
With enough advance work, every new LED light fixture could also be wired into the network backbone, accomplishing ubiquitous wireless communications to any device in a room without burdening the already crowded radio-frequency bands. Visible light communications (VLC) is being refined by industry, standards groups and well-funded government initiatives. And the stakes are enormous, since the traditional lighting market is measured in trillions of dollars and the transition to solid-state has already begun.
Researchers to Advance Smart Lighting with BU Prototype
Boston University College of Engineering, 10 May 2010
Smart lighting—the use of highly energy-efficient and controllable solid-state light sources both to illuminate a defined space and facilitate optical wireless communication among electronic devices within that space—recently took a major step forward. In April Professor Thomas Little (ECE) began fabricating a new LED-based prototype that the National Science Foundation Smart Lighting Engineering Research Center at Boston University developed over the past year. Fulfilling an initial order for 40 units, Little is now shipping these devices to the Center’s industrial and educational outreach partners, a development that could spark new advances leading to commercialization.
“We now have a working system that's robust enough to send to others to experiment with,” said Little, co-principal investigator and associate director of the NSF Smart Lighting Engineering Research Center, a program involving BU, Rensselaer Polytechnic Institute (RPI) and the University of New Mexico that facilitates research, industrial collaborations and educational initiatives aimed at advancing intelligent lighting systems and the development of transformative uses of light. “Our industrial partners and others can use this prototype as a reference design that they can adapt to develop a commercially viable system.”
Wireless optical transmission key to better indoor communications
Pennsylvania State University, 27 January 2010
San Francisco -- Light is better than radio waves when it comes to some wireless communications, according to Penn State engineers. Optical communications systems could provide faster, more secure communications with wider bandwidth and would be suitable for restricted areas like hospitals, aircraft and factories.
Sending information via light waves either in physical light guides or wirelessly is not new, but existing wireless systems either require direct line of sight or are diffused and have low signal strength. The researchers chose to take a different approach using multi-element transmitters and multi-branch optical receivers in a quasi-diffuse configuration.
Lights, signal, networking
The Guardian, 26 February 2009
What You See is What You Send
Engineering & Technology Magazine, 8 November 2008
Can visible-light communications help expand wireless technology beyond the limitations of the radio-frequency spectrum?
You’ve probably heard that the days of incandescent and fluorescent light bulbs are numbered. What you probably haven’t heard is that the light-emitting diodes (LEDs) that will soon replace them will not only be helping light your way; they will also be broadcasting digital information to help your gadgets communicate with each other and the Internet.
Creating Wireless Network Using Visible Light
Science Daily, 16 October 2008
Boston University's College of Engineering is a partner launching a major program, under a National Science Foundation grant, to develop the next generation of wireless communications technology based on visible light instead of radio waves.
Researchers expect to piggyback data communications capabilities on low-power light emitting diodes, or LEDs, to create "Smart Lighting" that would be faster and more secure than current network technology.
"Imagine if your computer, iPhone, TV, radio and thermostat could all communicate with you when you walked in a room just by flipping the wall light switch and without the usual cluster of wires," said BU Engineering Professor Thomas Little. "This could be done with an LED-based communications network that also provides light – all over existing power lines with low power consumption, high reliability and no electromagnetic interference. Ultimately, the system is expected to be applicable from existing illumination devices, like swapping light bulbs for LEDs."
Visible light data network under development
Science A Gogo, 7 October 2008
The next generation of wireless communications technology will use visible light instead of radio waves, with data piggybacking on interior lighting systems which researchers say will offer both greater speed and better security than today's radio networks. Boston University's College of Engineering (BU) is developing the "smart lighting" system using low-power light emitting diodes (LEDs) that can be switched on and off so rapidly that the change is imperceptible to the human eye.
Wireless Communications Technology Based on Visible Light
AZoOptics, 7 October 2008
Boston University's College of Engineering is a partner launching a major program, under a National Science Foundation grant, to develop the next generation of wireless communications technology based on visible light instead of radio waves. Researchers expect to piggyback data communications capabilities on low-power light emitting diodes, or LEDs, to create "Smart Lighting" that would be faster and more secure than current network technology.
Video: System for data transmission via visible light
Tech Crunchies, 23 June 2010
Transmitting data via light is hardly anything new, but what about sending and receiving information via visible light? Tokyo-based start-up Outstanding Technology is currently working on a system that uses visible LED light for the transmission of data and audio signals.
And because LED lighting may replace both incandescent and fluorescent lighting one day, the company expects “lighting infrastructure to become communication infrastructure” in the near future.
Outstanding Technology’s system makes it possible to set up a PC that accesses the web via LEDs and light receivers alone (see the video embedded below for a demo), for example. The company says in tests, it succeeded in voice transmission over a distance of 13km. Apparently, data transmission speed can reach up to 160Mbps.