IEEE Spectrum, 20 November 2014

Visible light communications could outshine Wi-Fi in industrial settings

Light fantastic:  A CMOS digital-to-analog converter developed at the University of Edinburgh helps LEDs act as communications devices.

As LEDs become a more common source for room lighting they’re opening a new pathway for linking mobile devices to the Internet, with the potential for wider bandwidth and quicker response time than Wi-Fi. At least that’s what researchers such as Harald Haas, chair of mobile communications at the University of Edinburgh, are hoping.

"All the components, all the mechanisms exist already," Haas says. "You just have to put them together and make them work."

Haas’s group, along with researchers from the Universities of ­Cambridge, Oxford, St. Andrews, and Strathclyde, are halfway through a four-year, £5.8 million project funded by the Engineering and Physical Sciences Research Council, in the United Kingdom. They are pursuing ultra­parallel visible light communication, which would use multiple colors of light to provide high-bandwidth linkages over distances of a few meters. Such a Li-Fi system, as it’s been dubbed, could supplement or in some instances replace traditional radio-based Wi-Fi, they say. But taking on such a broadly used radio technology is an uphill battle.

At the IEEE Photonics Conference in October, members of the consortium showed off the progress they’re making. For instance, the team has used commercially available red, green, and blue LEDs as both emitters and as photodiodes to detect light. By doing that, they created a system that could both send and receive data at aggregate rates of 110 megabits per second. When transmitting in one direction only, they reached a rate of 155 Mb/s.

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The Telegraph, 12 October 2014

British start-up invents light bulb fitting capable of acting as a wireless network in the home

A British hi-tech start-up has invented a light bulb fitting capable of acting as the equivalent of a wireless network in the home.

PureLiFi, a spin-out from Edinburgh University, is poised to announce new technology that can create a two-way high-speed connection using signals sent by LED lightbulbs for the first time.

The company’s creation has attracted the interest of a club of hi-tech investors who are close to agreeing a $10m (£6.2m) funding to help miniaturise and commercialise the system.

It is a box that can be connected to any ordinary light fitting with an LED bulb and turn it into a LiFi internet access point. The signals are encoded in a high frequency flicker many thousands of times faster than the human eye can detect. At the other end of the box, a receiver picks up the signal and communicates back in infrared light. It is this device that Prof Harald Haas, the founder of PureLifi, plans to miniaturise using the incoming investment.

Prof Haas said that the creation of a "world first" two-way LiFi network was an "absolute essential development in proving this technology can be part of the Internet of Things".

The Internet of Things is a catch-all term for a trend toward more everyday devices being connected, such as thermostats and home security systems.

It is envisaged that eventually the internet will be used to monitor and control almost any domestic or industrial device. That would mean a major expansion in wireless networking capacity beyond what Wi-Fi can provide.

Prof Haas said: "Worldwide industry demand for this product shows that LiFi is viewed as a transformative technology that can change the way we use the mobile internet and be an enabler of the emerging Internet of Things."

PureLifi hopes that light-based wireless networking will become standard for 5G, the successor to the 4G networks currently being deployed by mobile operators, which is in the early stages of development.

The technology is currently being tried out by major airlines, which want to use it to provide better in-flight connectivity, and intelligence agencies, which are interested in the potential of LiFi for secure wireless data transfers.

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The Scotsman, 5 October 2014

A TECHNOLOGY start-up that uses beams of light to transmit data has been tipped as a flotation candidate, potentially worth "hundreds of millions of dollars", as it looks set to smash its fundraising targets.

PureLiFi, which was spun out from Edinburgh University in 2012, has already secured about £1.5 million from investors including business angel syndicate Par Equity and Scottish Enterprise.

As revealed by Scotland on Sunday in December, the firm has embarked on a further fundraising round aimed at bringing in about £3m, but is now poised to raise more than twice that figure. Edinburgh-based finance boutique Quest Corporate has been appointed to arrange the funding.

Quest Corporate founder Marcus Noble said PureLiFi, co-founded by chief science officer Harald Haas, "is a phenomenal business" with strong prospects for an initial public offering (IPO).

While current wi-fi systems use radio waves to transmit internet data and other information, LiFi equipment uses beams of light.

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The Next Web, 21 August 2014

Sir Alexander Graham Bell may be better known as the guy who invented the first ‘practical’ telephone, but the Scottish scientist laid claim to an arsenal of additional innovations.

Among these were the photophone, a wireless telephone of sorts that enabled sounds (including speech) to be transmitted via light. It’s said that Bell actually valued the photophone more than the telephone from his lifetime achievements, even though it never quite took off and is now consigned to the footnotes of history.

However, more than 130 years after the photophone first came to light, Professor Harald Haas is pioneering his own light-centric wireless communications technology. And ironically, he’s doing so from the Alexander Graham Bell building at the University of Edinburgh in Scotland.

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BBC News, 19 February 2014

Imagine a future where your internet connection is beamed across your office from the overhead lights.

Using a standard light fitting attached to an internet connection, LiFi sends data to a receiver attached to a computer by means of rapid, invisible, flickering of the light source.

Professor Harald Haas is now commercialising the technology with a company spun out of Edinburgh University.

Right now the prototype device is too large to be attractive to consumers, but the team says eventually it should be small enough to integrate into a mobile phone.

They will be showing off its capabilities at Mobile World Congress in Barcelona. Professor Haas demonstrated the technology to Rory Cellan-Jones.

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BBC News, 18 October 2013

Wi-fi connectivity from a light bulb - or "li-fi" - has come a step closer, according to Chinese scientists.

A microchipped bulb can produce data speeds of up to 150 megabits per second (Mbps), Chi Nan, IT professor at Shanghai's Fudan University told Xinhua News.

A one-watt LED light bulb would be enough to provide net connectivity to four computers, researchers say.

But experts told the BBC more evidence was needed to back up the claims.

There are no supporting video or photos showing the technology in action.

Li-fi, also known as visible light communications (VLC), at these speeds would be faster - and cheaper - than the average Chinese broadband connection.

In 2011, Prof Harald Haas, an expert in optical wireless communications at the University of Edinburgh, 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 and set up a private company, PureVLC, to exploit the technology.

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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.

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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.

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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.

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Light Talk, 16 August 2011

One of the things that has not stopped amazing me is the continuous technological developments in the lighting industry ever since I started my career now 30 years back. In my early days we had the 40mm fluorescent tubes, a couple of incandescent lamps including the good old PAR reflector lamp and a few gas discharge lamps like mercury vapour, sodium and a bit of metal halide, all old technology. Over the years these technologies improved dramatically (tri-fosfor, high frequency, compact fluorescent, white sodium, new generation metal halide, halogen, ec) and new technologies such as induction, fiber optic and the last couple of years the incredible developments with LED lighting.

Now something new is about to hit us if we can believe Harald Haas, a professor in digital communication teaching and researching simultanously in universities in Edinburgh, Scotland and Bremen, Germany. Research in these universities has focussed around white light communication and infrared technology respectively. One of the key technologies he has been researching is LED data transfer technology! Basically using light as the medium to transfer data. Using light in itself to transmit data is nothing new (fiber optic cables!) but using visible light (something we use in our everyday life) to communicate is. By inserting tiny transceivers in an LED light bulb, the light beam can be used to transfer data. Considering that there are many billions of light bulbs installed all over the world, this technology potentially opens up data transfer opportunities exponentially compared to the wireless technology we are accustomed to now. The technology can work on direct as well as reflective light which overcomes one of the main hurdles of obstacles obstructing a light beam. The technology would also work very well under water.

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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.


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.

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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.

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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.

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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.

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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.

Read more and watch video

LED's used for lighting in home and office, and used for data transfer at the same time, used for wireless internet connection.


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.

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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.”

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