Communicating LED lamps

LEDs are used for a long time for all kinds of data communications applications ranging from wireless IR remote controls and IrDA to wired fiber optics communication. There has been many years ago also ideas on optical wireless LANs based on infrared, but they faded quickly. But now when LED lights are becoming very popular this idea could see a second coming.

Ceiling lights in Minn. send coded Internet data article tells about LED lights that will transmit data to specially equipped computers on desks below by flickering faster than the eye can see. The first few light fixtures built by LVX System will be installed in six municipal buildings in the central Minnesota. The LVX system puts clusters of its light-emitting diodes in a standard-sized light fixture. The LEDs transmit coded messages A light on the modem talks back to the fixture overhead, where there is sensor to receive the return signal and transmit the data over the Internet. It works in almost exactly the same way that fiber optic systems do, except the sender and receiver aren’t connected by a cable. Communicating lights are set up using just ordinary power connections. The first generation of the LVX system will transmit data at speeds of about 3 megabits per second. If you are interested check video from Get ElectricTV.

vermeil_IEC_LED_Symbol

There is another application that also combines wireless communications and LED lights. Finnish article Wlan ohjaa yksittäisiä led-loisteputkia (read English translation) tells about LED light tubes can be controlled by a WLAN connection, even individually. Finnish company Valtavalo has licensed Netled control technology from Yashima Dengyo Co., Ltd. and sells their products. Netled technology is designed to provide means to monitor in electricity consumption in real time and control the various LED light tube groups.

73 Comments

  1. Tomi Engdahl says:

    Wi-fi from lasers
    White light from lasers demonstrates data speeds of up to 2 GB/s
    http://www.eurekalert.org/pub_releases/2016-08/kauo-wfl081116.php

    A nanocrystalline material that rapidly makes white light out of blue light has been developed by KAUST researchers.

    While Wi-Fi and Bluetooth are now well established technologies, there are several advantages gained by shortening the wavelength of the electromagnetic waves used for transmitting information.

    So-called visible-light communication (VLC) makes use of parts of the electromagnetic spectrum that are unregulated and is potentially more energy-efficient. VCL also offers a way to combine information transmission with illumination and display technologies–for example, using ceiling lights to provide internet connections to laptops.

    Many such VLC applications require light-emitting diodes (LEDs) that produce white light. These are usually fabricated by combining a diode that emits blue light with phosphorous that turns some of this radiation into red and green light. However, this conversion process is not fast enough to match the speed at which the LED can be switched on and off.

    “VLC using white light generated in this way is limited to about one hundred million bits per second,” said KAUST Professor of Electrical Engineering Boon Ooi.

    The team created nanocrystals of cesium lead bromide that were roughly eight nanometers in size using a simple and cost-effective solution-based method that incorporated a conventional nitride phosphor. When illuminated by a blue laser light, the nanocrystals emitted green light while the nitride emitted red light. Together, these combined to create a warm white light. The white light generated using their perovskite nanostructures was of a quality comparable to present LED technology.

    This meant they could modulate the optical emission at a frequency of 491 Megahertz, 40 times faster than is possible using phosphorus, and transmit data at a rate of two billion bits per second.

    Reply
  2. Tomi Engdahl says:

    Lifi is a technique in which data is transferred by means of näkyävn light flicker. The German Fraunhofer Institute fotonic systems research lab scientists have developed a module that would fit the wireless data transfer to industry applications.

    According to researchers lifi may facilitate the development of the Internet of industrial equipment with machines, production and logistics fully automated and monitored in all sensors. Machine control requires in many cases, virtually real-time, that is, the delay can be up to the order of milliseconds between the sensor and the actuator.

    Developed by German researchers lifi module “GigaDock” solves many of these problems. The visible light by means module is capable of transferring data at up to 12.5 gigabits per second

    Testing the latency was reduced to less than one milliseconds, which enables real-time control of machinery.

    GigaDOck-in module is a Gigabit Ethernet interface, so it can be integrated into existing industrial networks. A couple of weeks to get to the Hanover trade fair ECOC scientists promise to try the demo and industry lifi a wireless network in which devices are controlled wirelessly up to 10 meters away.

    Source: http://etn.fi/index.php?option=com_content&view=article&id=4942:ledidata-korvaa-ethernetin&catid=13&Itemid=101

    Reply
  3. Tomi Engdahl says:

    Hackaday Prize Entry: Cheap Visible Light Communication
    http://hackaday.com/2016/09/03/hackaday-prize-entry-cheap-visible-light-communication/

    [Jovan] is very excited about the possibilities presented by Visible Light Communication, or VLC. It’s exciting and new. His opening paragraphs is filled with so many networking acronyms that VLC could be used for, our browser search history now looks like we’re trying to learn english without any vowels.

    Visible Light Communication for the masses
    https://hackaday.io/project/12556-visible-light-communication-for-the-masses

    This project will focus on making current research in field of Visible Light Communication (VLC and LiFi) usable and meaningful for use.

    So far I spend some serious amount of time developing usable low-cost VLC solution that can find its way to every day use in PAN networks. My primary idea is to enable Sensor/IoT to MCU/SOC or MCU to SOC low power intercommunication (M2M) in visible light spectrum.
    VLC systems are far beyond EM spectrum that is regulated by gov. agencies and is by default free, open and dose not require licensing. But best part is its width that can in future provide million times greater bandwidth that whole 10k-300GHz Radio EM spectrum.

    Reply
  4. Tomi Engdahl says:

    Sending Music Long Distance Using A Laser
    http://hackaday.com/2016/09/25/sending-music-long-distance-using-a-laser/

    This isn’t the first time we’ve seen DIYers sending music over a laser beam but the brothers [Armand] and [Victor] are certainly in contention for sending the music the longest distance, 452 meter/1480 feet from their building, over the tops of a few houses, through a treetop and into a friend’s apartment. The received sound quality is pretty amazing too.

    the light of the laser is modulated with a signal directly from the audio source, making it an analog transmission. The laser is a 250mW diode laser bought from eBay. It’s powered through a 5 volt 7805 voltage regulator fed by a 12V battery.

    They receive the beam in their friend’s apartment using solar cells, which then feed a fairly big amplifier and speakers. From the video you can hear the surprisingly high quality sounds that results.

    Music by LASER : DIY Experiments [#3] Sound transfer by light / LASER music air / light music
    https://www.youtube.com/watch?v=DtCwJU6YMaA

    Reply
  5. Tomi Engdahl says:

    The DarkLight Rises: Visible Light Communication in the Dark
    http://dartnets.cs.dartmouth.edu/darklight

    Visible Light Communication (VLC) emerges as a new wireless communication technology with appealing benefits not present in radio communication. However, current VLC designs commonly require LED lights to emit shining light beams, which greatly limits the applicable scenarios of VLC (e.g., in a sunny day when indoor lighting is not needed). It also entails high energy overhead and unpleasant visual experiences for mobile devices to transmit data using VLC. We design and develop DarkLight, a new VLC primitive that allows light-based communication to be sustained even when LEDs emit extremely-low luminance. The key idea is to encode data into ultra-short, imperceptible light pulses.

    Our DarkLight prototype supports 1.8-m distance with 1.6-Kbps data rate.

    The DarkLight Rises: Visible Light Communication in the Dark (MobiCom 2016)
    https://www.youtube.com/watch?v=qwxLYC2z1C0

    Reply
  6. Tomi Engdahl says:

    Connected Offices through VLC
    http://www.usa.lighting.philips.com/systems/connected-lighting-for-offices

    Connected lighting is part of the Internet of Things (IoT) trend. By building on the digital nature of LED technology, connected lighting brings illumination and IT together. With the help of PoE technology not only power and data can be delivered for the luminaire over a standard Ethernet cable but it also allows the lighting system to be merged with the IT system. Moreover, Philips PoE (power over ethernet) enabled luminaires also incorporate Visible Light Communication (VLC) technology wherein the PoE luminaires continuously transmit their IP address at higher frequency which in turn can be detected by a smartphone app allowing app based controllability and personalization of lights.

    Reply
  7. Tomi Engdahl says:

    Philips acquires French Li-Fi company
    http://www.ledsmagazine.com/articles/2017/02/philips-acquires-french-li-fi-company.html?cmpid=enl_leds_ledsmagazine_2017-02-08&email_address=tomi.engdahl@netcontrol.fi&eid=289644432&bid=1658407

    The Dutch lighting giant quietly picked up Luciom late last year, and has already moved it to Eindhoven.

    Holland’s Philips Lighting has quietly acquired a small French company specializing in visible light communications (VLC) in a move believed to be aimed at boosting Philips’ capabilities in Li-Fi, the light-based technology expected to provide Wi-Fi-like two-way Internet communications.

    “Philips Lighting acquired Luciom at the end of 2016,” a Philips spokesperson confirmed for LEDs Magazine, noting that all eight of Luciom’s employees now work for Philips.

    Reply
  8. Tomi Engdahl says:

    Nanorods Emit and Detect Light, Could Lead To Displays That Communicate Via Li-Fi
    https://hardware.slashdot.org/story/17/02/11/0218222/nanorods-emit-and-detect-light-could-lead-to-displays-that-communicate-via-li-fi?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+Slashdot%2Fslashdot%2Fto+%28%28Title%29Slashdot+%28rdf%29%29

    Ever since 2015 Consumer Electronics Show, quantum dots have been in a market struggle to displace light-emitting diodes (LEDs) as a backlight source for liquid crystal displays (LCDs). Now an advance by a team of researchers from the University of Illinois at Urbana-Champaign, the Electronics and Telecommunications Research Institute in South Korea and Dow Chemical may turn the display market on its head by eliminating the need for backlights in LCD devices. They have produced a LED pixel out of nanorods capable of both emitting and detecting light.

    Nanorods Emit and Detect Light, Could Lead to Displays That Communicate via Li-Fi
    http://spectrum.ieee.org/nanoclast/semiconductors/optoelectronics/nanorods-emit-and-detect-light-enabling-displays-to-communicate-via-li-fi

    “If you want to operate an LED or a photdetector or a photovoltaic, you have to either inject electron holes, positive and negative charges into this quantum dot for light emission, or extract those charges out,”

    “Our proof-of-concept devices show how LEDs can play multifunctional roles from light detection to data communication, ranging from visible light communication, such as Li-Fi, to energy harvesting/self powered displays,” said Oh in an e-mail interview with IEEE Spectrum.

    Reply
  9. Tomi Engdahl says:

    Editor’s Picks
    February 1, 2017
    http://www.cablinginstall.com/articles/print/volume-25/issue-2/departments/editor-s-picks.html?cmpid=enl_cim_cimdatacenternewsletter_2017-02-27

    Light fidelity (LiFi) technology transmits data through light, turns lamps into wireless Internet access points

    Professor Harald Haas, CSO of pureLiFi and Professor of Mobile Communications at the University of Edinburgh, received the International Solid State Lighting Alliance (ISA) Award for Outstanding Achievement in Beijing, China this past November. The award, presented at the 13th International Forum on Solid State Lighting, relates to Professor Haas’s contribution to diversify the applications of solid state lighting (SSL) technology. According to the forum, “LiFi, which stands for ‘light fidelity’, is a technology that can transmit data through light and turn the lamps in every office, home, car or streetlight into wireless Internet access points. It offers higher speeds than traditional wireless technology, greater security and the potential to deliver unprecedented bandwidth and data density.” 2014 Nobel Prize for Physics winner and previous winner of the Outstanding Achievement, Professor Shuji Nakamura, presented Professor Haas with the award.

    Professor Haas was recognized as the “father of LiFi” after introducing the technology to the world at a TED Global talk in 2011, where he demonstrated light fidelity for the first time and coined the term LiFi. The company he founded in 2012, pureLiFi, is at the forefront of the commercialization of LiFi technology, and in 2016 launched the world’s first LiFi dongle-“LiFi-X”-and integrated LiFi luminaire.

    Haas established the world’s first LiFi center in 2013, when the LiFi Research & Development Center opened at the University of Edinburgh. The center now leads cutting-edge R&D, including pioneering work into the use of solar panels as receivers, in a move which Haas says could help tackle Internet access problems in the developing world-the so-called “digital divide.”

    Reply
  10. Tomi Engdahl says:

    Mobile World Congress 2017: PureLiFi Debuts New Li-Fi Luminaire and Shares Progress on Commercial Pilots
    http://spectrum.ieee.org/tech-talk/telecom/internet/mobile-world-congress-2017-purelifi-debuts-new-lifi-luminaire-and-shares-progress-on-commercial-pilots

    In real-world settings, the company’s products deliver data rates of about 45 Mbps for both uploads and downloads.

    There are some special considerations that come with using Li-Fi, such as the fact that light doesn’t penetrate walls, so every room in a house would need a Li-Fi–enabled lighting fixture. However, PureLiFi likes to pitch this factor as a feature that also keeps users’ data secure, since communications are inaccessible to anyone who is not in the same room.

    Banham and Haas know that Li-Fi will not be widely adopted until it is integrated into the chipsets of laptops, tablets, and smartphones. In the meantime, Banham points out that both Wi-Fi and Bluetooth also started out with dongles, and that it took nearly a decade for those technologies to move to chipsets and become widely adopted

    Ultimately, Haas doesn’t view Li-Fi as a replacement for other wireless technologies such as 5G for cellular networks or Wi-Fi. Instead, he thinks Li-Fi will work hand-in-hand with existing technologies to provide the most bandwidth to users, rather than compete with them.

    Reply
  11. Tomi Engdahl says:

    Philips taps Microsoft as part of indoor-positioning partnering push, adds Bluetooth to the mix
    http://www.ledsmagazine.com/articles/2017/02/philips-taps-microsoft-as-part-of-indoor-positioning-partnering-push-adds-bluetooth-to-the-mix.html?cmpid=enl_ledsmagazine_showdailyvideoenewsletterstrategiesinlight_2017-03-01

    With location-based services still stuck on the launchpad, the company’s new “Location Lab” reaches out to data and app developers. Meanwhile, Philips finally acknowledges that Bluetooth, not just VLC, can light the way.

    In two moves to jump-start the stalled indoor-positioning business, Philips Lighting said it has rounded up IT companies including Microsoft and SAP to develop compelling data-linked uses that might actually attract customers. And in an underlying wireless technology change, Philips quietly revealed that it is now embracing radio-based Bluetooth in addition to the visible light communication (VLC) that it has long preferred.

    Indoor positioning — also known as location-based services — transmits signals to smartphones in order to guide and engage people around buildings such as retail stores and offices. Lighting companies want to use ceiling luminaires to send the signals. Philips has persistently championed VLC, which embeds signals in the modulation of lightwaves emitted by LEDs. Other vendors such as Osram and startup Gooee prefer Bluetooth beacons that send signals from chips inside light fixtures.

    Regardless of the technology, one of the big early adapters is supposed to be the retail industry, which would guide shoppers around physical stores, pinging them with discounts of interest to the individual based on buying history, loyalty programs, and the like. The schemes represent a potential bonanza in the buying and selling of data that can be analyzed, scrubbed, and repurposed across many industries.

    Success in the retail area will require the buy-in of large retail chains and brands.

    To help develop broader applications for the technology, Philips today launched a new initiative called the Location Lab partner program, whose initial members include Microsoft, SAP, and Capgemini, among others.

    The fortified partnership emphasis echoes a strong push by Philips rival GE, where the newfangled lighting division — called Current, powered by GE — has over the last year signed a number of indoor-positioning partners.

    Like Philips, GE has had a notable dearth of public indoor-positioning announcements, even though GE began heavily promoting retail use some three years ago

    Another large Philips rival, Osram launched its indoor positioning a year ago but has yet to announce a retail deployment

    One lighting company that could be making headway is Atlanta-based Acuity Brands, which last month said it has now installed Internet of Things (IoT) lighting in nearly 40 million ft2 of retail space. Lighting-based indoor positioning is a type of IoT lighting.

    Target uses both VLC and Bluetooth technologies in its indoor-positioning trials.

    Until now, Philips has steadfastly backed VLC, a light-based technology that provides better accuracy than Bluetooth does — VLC will steer a shopper closer to the beer or soap or whatever they desire. But one of VLC’s drawbacks is that it requires a phone to be in direct line-of-sight with a luminaire. Bluetooth, which uses radio frequencies rather than lightwaves, does not require such direct contact.

    Philips has now added Bluetooth to its positioning topography, even if it did not go out of its way to proclaim the move.

    Philips’ Location Lab announcement comes on the heels of its acquisition of French VLC specialist Luciom.

    In its incipient form, one of Li-Fi’s principle advantages is that it can augment the amount of bandwidth available for wireless Internet, because the light spectrum is somewhere between 1000 and 10,000 times wider than the radio spectrum

    Acuity says it has deployed IoT lighting in 40 million square-feet of retail space
    http://www.ledsmagazine.com/articles/2017/01/acuity-says-it-has-deployed-iot-lighting-in-40-million-square-feet-of-retail-space.html

    LED lighting vendor Acuity Brands said it has now deployed lighting-based indoor positioning systems (IPS) in nearly 40 million ft2 of retail space, a claim it made as it and software giant Microsoft jointly showed off Internet of Things (IoT) technology at the National Retail Federation exhibition in New York.

    The two companies showed Acuity luminaires communicating information to in-store shoppers and sending data to Microsoft’s Azure cloud computing system to discern useful retail patterns and insights. Acuity reported significant headway since demonstrating IPS with Microsoft at the same show last year.

    Target in particular has gained attention for trialing IPS, as LEDs sister magazine Lux Review first revealed nearly two years ago.

    By November of 2015, at least 100 Target locations were known to have trialed IPS technology, a number that could well have surged by now.

    Acuity’s lighting-based IPS communicates with end users’ smartphones via either the modulation of LED lightwaves — a technology known as visible light communication (VLC) — or via Bluetooth chips embedded in ceiling luminaires. Either way, the lights can welcome the shopper to the store and then direct him or her to discounts of particular interest to that individual. The system can then send data about the customer’s actions to the cloud, giving the retailer and its suppliers valuable insights on sales and shopper behavior.

    Reply
  12. Tomi Engdahl says:

    The resolution of converging lines of interest – The LED Story
    http://www.ledsmagazine.com/articles/2017/02/the-resolution-of-converging-lines-of-interest-the-led-story.html?cmpid=enl_ledsmagazine_showdailyvideoenewsletterstrategiesinlight_2017-03-01

    This industry is experiencing an unimaginable whirlwind of technical directions in which it can move. With the Internet of Things (IoT), LED lasers, Li-Fi (light fidelity), high power, chip-on-board (COB), flip chip, etc., the topics and terms are endless. The Pandora’s Box of issues related to a new technology and a rush to market has been opened.

    The lighting industry had been static or at least in flux in past years. The advent of solid-state lighting (SSL) was, in fact, a panacea for the Illumination world. Companies had reached the end of discharge lighting potential and phosphor performance marks. LED lighting arrived on the scene at a perfect time to pump life into a commoditized world. But that’s what capitalism does to all products bought and sold. When creativity becomes stagnant and good ideas wane, they reach back into the box and recycle. We shouldn’t worry about the next big thing — rather, what we can do with an aging infrastructure of 100-plus-year-old legacy lighting? Is now the time to change? With a clean slate in front of us, would we choose an Edison socket?

    As I have said on numerous occasions, “We are not alone.” Many other industries (i.e., information technology) see the lighting pie as delicious and are ready to take a bite. The problem is we (lighting folks) see it as the whole meal, not just the dessert. Apple, Google, and Amazon are poised and ready to feast at any moment. With SSL, the possibilities are endless and that is the crux of the issue.

    Reply
  13. Tomi Engdahl says:

    Infrared 42.8 gigabits online

    Stuck with a home Wi-Fi network? No worries. Dutch PhD student has developed based on infrared technology, which the user gets over 40 Gigabit connection to themselves.

    It is Einhovenin University of Technology doctoral student Joanne Oh’s work, which he used infrared rays to transfer data. Each device gets its own network infra-red rays, which data is transferred to 42.8 gigabits per second.

    Joanne Oh’s concept is not only effective, very affordable. Data users should be installed on the ceiling a few “light antennas” who can head to the rays accurately. The antenna consists of a pair of optic fiber, which do not require maintenance and power supply.

    It is also a very safe technique. The beam wavelength of about 200 terahertz, so it will never be maintained on the retina of the eye. Each antenna can serve multiple devices, because each issued its own wavelength.

    The concept could develop to commercial use within five years.

    Source: http://www.etn.fi/index.php/13-news/6060-infrapunalla-kotiin-42-8-gigabitin-netti

    Reply
  14. Tomi Engdahl says:

    Infrared light could someday deliver super-fast WiFi
    A student’s PhD dissertation proposes a high-speed system with no interference.
    https://www.engadget.com/2017/03/17/infrared-super-fast-wifi/

    WiFi has become essential to our everyday lives, which is why slow speeds piss us all off. Luckily, a PhD student in the Netherlands has come up with a potentially groundbreaking idea: using infrared rays to carry wireless data to your laptop or smartphone.

    The capacity of the proposed system is massive, with more than 40 gigabits per second possible per light ray. Contrast that with current 802.11ac, which can transmit up to 1 gigabit per second. This new infrared system can target multiple devices at once, is cheap to set up and doesn’t have any issue with radio interference, unlike traditional WiFi. The research team has only tested download speeds and only across short distances, but the potential is clear.

    Wi-fi on rays of light: 100 times faster, and never overloaded
    https://www.tue.nl/en/university/news-and-press/news/17-03-2017-wi-fi-on-rays-of-light-100-times-faster-and-never-overloaded/

    Reply
  15. Tomi Engdahl says:

    Infrastructure-based wireless technology has been developed at Eindhoven University of Technology for up to 300 times faster data transfer rates than existing wifi networks. Reported by Reuters.

    According to Professor Ton Koonen, each light beam acts as a high capacity channel. – It’s kind of like fiber optic fiber but without fiber. Until now, we’ve got a link to the data rate of 112 gigabytes

    The transmitter consists of several antennas. If your smartphone or tablet moves away from the antenna view, the data goes through the second antenna.

    According to Noonen, the system is very easy to maintain because it has no moving parts.

    The infrared beam does not pass through the walls, so the connection is protected within the walls of one room. Noon’s research team wants to commercialize technology over the next five years.

    Source: http://www.etn.fi/index.php/13-news/6674-300-kertaa-nopeampaa-wifia

    Reply
  16. Tomi Engdahl says:

    London scientists propose 10Gbps home wireless network using Li-Fi and 5G
    http://www.cablinginstall.com/articles/pt/2017/09/london-scientists-propose-10gbps-home-wireless-network-using-li-fi-and-5g.html?cmpid=enl_cim_cim_data_center_newsletter_2017-09-21

    A team working out of Brunel University London has secured £720,000 of funding from Europe’s Horizon 2020 Program in order to help them develop a 10Gbps capable home wireless network using hybrid Li-Fi (Light Fidelity) and mmWave tech inside LED [Light-Emitting Diode] room lights.

    As reported by the UK’s ISPreview, “the goal is to create a 10Gbps (Gigabits per second) local wireless network in homes and buildings (offices etc.) with a delay of just 1ms (millisecond). The new network would make use of both Li-Fi and 5G wireless technologies in the millimeter Wave (mmWave) frequency bands.”

    London Scientists Prep 10Gbps Home Wireless Network Using Li-Fi and 5G
    https://www.ispreview.co.uk/index.php/2017/09/london-scientists-prep-10gbps-home-wireless-network-using-li-fi-5g.html

    Electronics and software engineers at Brunel University London are just one of the teams working on Li-Fi solutions as part of a 3 year project. The goal is to create a 10Gbps (Gigabits per second) local wireless network in homes and buildings (offices etc.) with a delay of just 1ms (millisecond).

    The new network would make use of both Li-Fi and 5G wireless technologies in the millimeter Wave (mmWave) frequency bands, although judging by the diagram above it’s probably not something that an ordinary home owner would want to install; unless you’re happy with running lots of optical fibre cable around your various light fittings. However it may have applications in other fields.

    The current plan is to develop and install a “remote radio-light head 5G” demonstrator hybrid Li-Fi / mmWave network and advise on systems in a Paris Museum (Musée de la Carte à Jouer), as well as an unnamed Madrid underground station and a Chinese supermarket. The team suggests that it could also find its way into tube stations, airports, planes, trains, schools and hospitals.

    Reply
  17. Tomi Engdahl says:

    Infrared Light Promises Ultrafast Wireless Communications
    https://spectrum.ieee.org/tech-talk/telecom/wireless/infrared-light-promises-ultrafast-wireless-communications

    Now, a research group in the Netherlands is proposing to increase wireless capacity by orders of magnitude by using infrared light instead of radio waves.

    The proposed system uses infrared antennas to steer light beams toward connected devices, and reaches a bitrate of 112 gigabits per second (Gb/s).

    “Wi-Fi’s getting congested everywhere,”

    In his setup, data is carried on a beam from an infrared laser—the same sort used in telecommunications networks—to an array of optical fibers.

    The fibers shine their beams, which have wavelengths between 1529.10 and 1569.80 nanometers, onto a pair of arrayed waveguide gratings. The gratings act like a filter, directing each beam in a particular direction based on its wavelength. A lens focuses the beams, coming out of a router on the ceiling of the room, into individual spots.

    Where those spots land is where the tablet or smartphone ought to be. Those devices would be equipped with an infrared receiver, consisting of a wide-aperture lens with a wide viewing angle, and photodiodes to convert the optical signal to an electrical one. If the person using the tablet is walking around the room and wanders out of view of one antenna, the system switches to another antenna. The location of the device can be tracked using its Wi-Fi radio.

    In theory, Koonen says, data from the device could be sent back optically as well, but that’s a trickier system to design, so at first uploads would be sent via Wi-Fi.

    Reply
  18. Tomi Engdahl says:

    German high school transmits lessons via the lights
    http://www.ledsmagazine.com/articles/2017/11/german-high-school-transmits-lessons-via-the-lights.html?eid=293591077&bid=1919307

    The idea of using LED ceiling lights to transmit Wi-Fi-like Internet signals continues to move slowly forward, as a German high school is deploying a prototype Li-Fi system in a specially equipped classroom to deliver lessons to students’ laptops.

    The school in Stuttgart, called Hegel-Gymnasium, is using the room to teach a broad range of subjects — everything from history to information technology. Five ceiling lights send wireless signals to small tabletop boxes, which then transmit to laptops via Ethernet cable. Each light covers 2m2, and each box can support up to four laptops or other devices.

    The prototype lights and boxes come from Berlin’s Fraunhofer Heinrich Hertz Institute HHI.

    Li-Fi, short for light-fidelity, is a two-way form of visible light communication (VLC), an emerging technology that uses invisible modulations in LED light frequencies to embed data. Proponents say that it will open up a vast amount of spectrum that will be needed as Wi-Fi waves saturate. Wi-Fi is a radio technology.

    Li-Fi enthusiasts also note that Li-Fi is not susceptible to interference the way Wi-Fi is (although Li-Fi requires line of sight), it does not emit electromagnetic radiation, and it is more secure.

    “We are happy that our students are involved with a sensational research project, which is concerned with high-speed data communication without electromagnetic interference,”

    Translation: The school is kicking the tires on Li-Fi and will provide insights that will help Fraunhofer improve the technology so it is more prime-time ready. It will also help tailor it for classroom settings.

    “The modern schoolroom needs new solutions for flexible data exchange,” Fraunhofer project manager Anagnostis Paraskevopoulos told LEDs Magazine. “We believe that the VLC technology offers a genuine alternative to radio-based systems.”

    Fraunhofer began developing the classroom earlier this year and will use the deployment to further troubleshoot Li-Fi and move it out of what Fraunhofer called the “prototype stage.”

    One thing holding back Li-Fi is that device manufacturers have not yet embedded Li-Fi chips inside phones, tablets, and laptops, whereas they long ago began embedding Wi-Fi.

    While Fraunhofer’s Li-Fi has a shorter range than Wi-Fi, that can be an advantage, because Wi-Fi’s range is what can often cause different Wi-Fi networks to clash, he added.

    Paraskevopoulos was optimistic about the future for Li-Fi.

    Reply

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