A key enabler for big data is big pipes — getting massive amounts of data to and from connected objects and machines. Visible light communication (VLC) is a class of technologies for wirelessly transmitting and receiving information using light (from infrared, through visible, into ultra-violet visible light spectrum of about 400 THz to 800 THz) instead of radio waves. While light signaling and semaphores have existed for millennia and infrared remotes and fiber optic cables have provided light-based communication for decades, the modern wireless VLC concept originated in Japan’s Nakagawa Laboratories in 2003. In late 2010 the IEEE published the 802.15.7 standard for Short-Range Wireless Optical Communication Using Visible Light, and LVX System launched a commercial product. University of Edinburgh Professor Harald Hass introduced a VLC protocol, “Li-Fi,” at a 2011 TED Talk, and the comparison with Wi-Fi helped awareness of the concept spread. Also that year, the European Union’s Omega Project wrapped up, VLC platforms ByteLight and Outstanding Technology launched, Disney Research showed off simple VLC applications in toys and children’s clothing, and Qualcomm developed its Lumicast technology for light-emitting diode (LED) lighting.
Still, the concept remained an engineering curiosity until 2015 and 2016, when technical and commercial milestones began to snowball: most notably, Estonian Velmenni’s “Jugnu” Li-Fi demonstrated data transfer at 1 Gbps, or about 100 times faster than Wi-Fi. Indian researchers developed Triplet Li-Fi (T-Li-Fi) using three colors, each carrying different data streams, thus tripling conventional Li-Fi capacity. Haas’s team projected commercial speeds up to 100 Gbps, and University of Oxford Li-Fi researchers hit 224 Gbps in lab conditions (fast enough to download five HD movies in about one minute). The Li-Fi Centre at the University of Edinburgh hopes to “fully harness the commercial and innovative potential of Li-Fi, and to help establish a major new £5 billion ($8.5 billion) Li-Fi industry by 2018.” The Li-Fi Consortium is a nonprofit developing concepts like Li-Fi repeaters that help signals propagate through walls; OpenVLC is a project to develop open-source, software-defined Li-Fi; and there is even Arduino code on GitHub for makers to build VLC systems at home.
On the commercial side, Haas’s company, pureLiFi, announced it will ship its first Li-Fi-enabled illumination and data transfer system (created in partnership with LED maker Lucibel) later this year. The system consists of a modulator that connects to the lighting fixture and a USB dongle to connect a computer or television display. It also announced a deal with Apple, which would let iPhones use Li-Fi via the onboard camera. Dubai Silicon Oasis-based Zero.1 rolled out its smartphone-based Li-Fi system, and inked a deal with the city to be the first in the world to equip its streetlights with Li-Fi. Other startups all over the world, like France’s Oledcomm, Russian StinsComan’s Beamcaster and Mexico’s Sisoft, continue to push the technology forward, while global corporations like GE, LG Innotek, Philips, Samsung, Toshiba, Sharp, Panasonic, Cisco, Rolls Royce, Airbus and Acuity Brands subsidiary eldoLED are working on “internet of lights” (IoL) technology and applications, as well. OLEDCOMM has actually deployed in retail (leclerc) and in government-owned facilities like the Paris Metro.
As its name implies, Li-Fi is a potential substitute for Wi-Fi, but it has strengths and weaknesses that put it in contention with Bluetooth, near field communication, low-power wide-area network technologies like LoRa and Sigfox, and even industry-specific technologies like RFID or iBeacons. The primary constraint is the need for a line-of-sight link, usually no more than 10 meters away (Bluetooth range can be more than 50 meters), without interference by artificial light or bright sunlight. As noted above, the Li-Fi Consortium is addressing Li-Fi’s inability to penetrate walls with a repeater device, which reads signals in one room and repeats them in another. Others are using optical filters to make Li-Fi work in sunlight, and even outdoors (the IEEE 802.15.7 standard even defines the physical layer 1 (PHY I) for outdoor applications, although its speed is a very slow 267.6 kbit/s).
At the same time, Li-Fi signals are secure in that they cannot “leak out” of a space like radio signals do, and they can be blocked by simply putting the Li-Fi device (like a phone) in a pocket. Light-based signals are also useful in areas where electromagnetic interference can cause problems, like near MRI medical equipment or electrical transformer stations. In theory, it would be possible to use lenses to focus the signal into a linear point-to-point beam, which could provide a Li-Fi network with an effectively limitless area data rate, since each device communicating with the router could have multiple signals (whereas multiple Wi-Fi routers in a space interfere with each other). Li-Fi is potentially more energy efficient than even Bluetooth Low Energy, which benefits mobile, wearable and wireless devices where battery life and power management are important — and some researchers are developing optical power transfer technology that would allow the signal light to also repower the wireless device. The technology could even find a niche with consumers who fear the adverse effects of electromagnetic radiation; even if these are nonexistent, the perception of Li-Fi having a health advantage could turn into market momentum — and it has already been proposed by “electrosensitive” advocacy groups like the Bio-Electromagnetic Research Initiative.
Near-term applications already being pursued obviously include providing internet access to mobile devices in offices, homes, city streets and even aircraft; Airbus found the weight savings of Li-Fi over Wi-Fi and wired equipment like seatback screens to be substantial. In retail and warehouse logistics, Li-Fi can provide indoor positioning data, pinpointing an object to within about 10 cm, and even potentially providing orientation information (useful for knowing, for example, which direction a customer is looking).
Ultimately, however, the biggest impact of Li-Fi and its alternatives will not be from its present set of features. Within a few years, we expect to see it combining with other complementary technologies to create a new ubiquitous computing platform. Under this integration, every device large enough to mount an LED and a light sensor can be connected and even powered by Li-Fi. Any light bulb could include Li-Fi, a camera, microphone and speaker to function like an Amazon Echo — an unobtrusive, universal interface to the internet of everything. Given the low cost of the technology and low barriers to entry, the technology could deploy quickly. Those making or using connected devices, or objects electronically tagged and tracked, should begin prototyping Li-Fi-based alternatives today.
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