Riding the Waves of Light: Li-Fi is transforming light and data

By Jeff Gavin | Oct 15, 2021




It’s a wireless world: our phones are mobile, we can take our laptops anywhere and building design programs are now tablet-accessible. Heavy data demands, however, can often make wireless less nimble. Think of slower service, weak signals, video freeze-ups and other latency issues. Riding the waves of radio frequency can be great, until it isn’t. Light fidelity (Li-Fi) is a different kind of wireless that uses LED light to transmit data. Early adopters are trying it out, but whether Li-Fi causes a revolution remains to be seen.

Harald Haas, professor and chair of mobile communications at the University of Edinburgh, is considered the father of Li-Fi. He coined the phrase at his 2011 TEDGlobal talk in Edinburgh, Scotland. The following year, he co-founded a company now known as pureLiFi. Other players have since gotten involved from Europe, Australia, India, the Middle East and the United States.

Signify (formerly Philips Lighting) is fully on board with its line of TruLiFi products. Ed Huibers is the company’s segment leader for office and hospitality, TruLiFi.

Huibers believes the technology creates another avenue for data transmission alongside Wi-Fi, since “the lighting spectrum and putting data in lights is something we’ve known about for years,” Huibers said. “Maybe now its time has come.”

With Li-Fi, a USB access key or dongle receives the light fidelity signal, as shown here with Signify’s TruLiFi product. Courtesy of Signify

How it all works

Categorized as a visible light communication system, Li-Fi distinguishes itself through bidirectional transmission of light (uplink and downlink). A special LED luminaire with a signal-processing chip transmits data using emitted light. Current to the bulb modulates the light emitted at extremely high speeds imperceptible to the human eye. Data fed into the LED is sent to a photodiode (typically a USB insertable receiver) to be read and converted into a usable binary data stream. The photodiode can also uplink data back to the server. Li-Fi can run over visible light and infrared spectra. In lab testing, data transmission has been found to be 100 times faster than Wi-Fi.

The Li-Fi signal is stronger the closer it gets to a receiver. A ceiling distance of no more than 10 feet (6–9 feet ideally) from a Li-Fi-enabled device will offer a strong signal. An open office with the right ceiling height could be a good application, Huibers said.

To add Li-Fi to a new light fixture, a transceiver is inserted in a cavity in the luminaire.

“When added to an existing lighting installation, we typically put [the transceiver] separate from the fixture. It is using the invisible infrared spectrum, not adding or influencing the light level of a space,” Huibers said.

Any device that runs on a Li-Fi signal must be authenticated using a receiver device. Picture your laptop—to run on Li-Fi, it will need either a plug-in dongle or one that rests nearby. The laptop would also have to run where authentication between the signal and your laptop can be matched. A controller box rests in the ceiling and can accommodate ethernet ports, providing Li-Fi to several designated locations.

A Li-Fi signal stays within the room it is operating, because it can’t penetrate walls, so it is far less hackable than Wi-Fi. It could be used in a designated safe room where end-users are dealing with sensitive or confidential information.

“I can see security applications for defense, maybe healthcare, and other government installations,” Huibers said. “Li-Fi is also not sensitive to interference as radio signals can be, so it is much more stable, which is great for applications such as augmented reality and virtual reality.”

Huibers shared that his home’s wireless demands are distributed through cable connections for ethernet, Zigbee and Li-Fi. He uses infrared spectrum Li-Fi for his home office.

Signify’s TruLiFi product uses an LED fixture featuring a plug-in receiver to transmit a Li-Fi signal. Courtesy of Signify

“The principal of Li-Fi is like that of Wi-Fi, sending out a signal,” he said. “So, a Bluetooth signal would be translated and modulated, but with light and the light spectrum. The whole process is faster, too.”

Different markets can play to different Li-Fi strengths. For instance, though faster speed can be a selling point for Li-Fi, Huibers feels its strong, constant signal may be the better benefit in office applications. For healthcare, speed and bandwidth could be especially valued as Li-Fi’s imaging capabilities are untouchable compared to Wi-Fi. Li-Fi could also deliver on the promise of 5G.

Breaking it down, Wi-Fi operates at 2.4 or 5 gigahertz. Li-Fi runs at 300 terahertz (THz), an enormous bandwidth, making it extremely stable, fast and secure. One terahertz represents 1 trillion hertz (1,012 Hz), an exceptionally high frequency.

“The average radio wave is 1 meter,” Huibers said. “A light wave is a million times shorter, which allows us to add more data packages. Light bandwidth is also much bigger, ranging from infrared to ultraviolet. Your cable provider sells you speed packages that you can never reach on a consistent basis. Because radio waves are finite, there is only so much space to play. Light is infinite. Knowing that, the potential for Li-Fi is much bigger.”

Sold on the technology

Anthony Lawrence is CEO of Light Rider Inc., Columbia, Md. His company is active in Li-Fi, focusing on its security features.

“With Li-Fi, you really have an invisible cone of light over your workspace providing data with infinite bandwidth potential,” he said. “I am convinced that Li-Fi will be a primary communication tool in 10 to 15 years.”

Lawrence’s firm offers Quantum Li-Fi with its own quantum encryption, which adds another layer of protection against hacking. A 5W LED luminaire that transmits the light signal to a receiver features a chip ID designed and manufactured by ID Quantique. The Geneva, Switzerland-based company describes itself as a provider of quantum network encryption.

“Data is encrypted using a random stream of binary or hex data,” Lawrence said. “If the encryption [quantum] key is not being received by your device, you are locked out. Even if someone acquired someone’s quantum key, they would need that person’s laptop. Then they would have to find the location needed for the exact light to read the key. It is a super closed system.”

Lawrence also believes Li-Fi is fit for the manufacturing floor.

“In industrial spaces, we see Li-Fi as a superior wireless communication to guide automated manufacturing and robotics,” Lawrence said. “Li-Fi can be very IoT- or IIoT-friendly with good software. Basically, the Li-Fi system can send data to machines for automation purposes. Maybe you install Li-Fi above 3D printers or other electronic equipment. The lights also work underwater.”

Li-Fi is also compatible with power over ethernet to help mediate power usage.

“With Li-Fi, it is important to understand it becomes part of the building infrastructure as it uses your lighting,” Lawrence said. “You aren’t switching suppliers as you do with Wi-Fi. Beyond military, government and the medical field, we’ve found cloud storage companies interested in Li-Fi for its cybersecurity capability. Our product can combat ransomware, too.”

To generate Li-Fi and add a layer of security, a Light Rider GEN1 5W bulb is chip-equipped to communicate with a Quantum terminal. Light Rider’s Quantum Li-Fi uses an encryption based on a random stream of binary or hex data. Courtesy of Light Rider Inc.

Timing is everything

In 2016, Randy Reid was looking for the next big thing for his company LumEfficient, Brentwood, Tenn. As founder and president, he started out selling light-emitting plasma in 2010, but switched to LED in 2017. That year he found his next big thing.

“I was at LuxLive in London and interviewed Harald Haas,” Reid said. “I didn’t know Li-Fi was a real product at the time, but was interested in developing my own lighting products and wanted to stand out. Haas’ passion led me get involved in Li-Fi. I developed a Li-Fi desk lamp that we used as a proof-of-concept tool to demonstrate the technology. We show people Li-Fi’s wireless connectivity, and you shut down the connection by simply moving your laptop away from the desk lamp light.”

Reid’s 30W Li-Fi-enabled table lamp was recognized in 2018 by LightFair and the Illuminating Engineering Society. His company also developed a high-bay Li-Fi fixture.

“We wanted to be the king of Li-Fi in industrial, but interest in Li-Fi seemed to fall away in 2020. I am now seeing interest returning. If the industry can embed encrypted chips (receivers) within a device such as a laptop versus using an external dongle or key, I feel this technology could really take off. Costs will also need to come down,” he said.

For now, Reid is waiting for more Li-Fi adoption before he fully recommits to the technology. LumEfficient’s emphasis was and remains industrial lighting such as high bays. Reid also serves as the executive director of the National Light Bureau and is the founder and editor of the Edison Report, which follows the Li-Fi industry.

For a nascent market such as Li-Fi to grow, education and the opportunity for end-users to sample the technology is vital. That’s why Signify and Light Rider offer starter kits.

“New technologies take time,” Huibers said. “People need to try them out. You need to build a business case. We feel the security aspect of Li-Fi is one factor, and it’s attracting interest. The technology’s ability to ably handle large amounts of data is another appealing factor. Our earliest-of-early adopter Li-Fi customers from two or three years ago have returned wanting to implement Li-Fi more broadly. We tell the story of Li-Fi with the facility manager, the security manager and other stakeholder decision-makers. You can call Li-Fi a ‘niche,’ but it could be a big niche depending on the market.”

About The Author

GAVIN, Gavo Communications, is a LEED Green Associate providing marketing services for the energy, construction and urban planning industries. He can be reached at [email protected]

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