Cisco: Li-Fi can reach around corners

Last month, LEDs Magazine noted that networking giant Cisco is now talking up Li-Fi. At the time, we did not report on the extent of the enthusiasm. So we thought we’d add this: The engineer behind the push is encouraged by a science that could overcome Li-Fi’s line-of-sight limitations.

Because Li-Fi remains a relatively lesser known technology, we offer our usual refresher: Li-Fi, or light fidelity, is a technology that uses modulated light waves from LEDs to transmit data. It is like Wi-Fi in that it provides wireless internet connections. But where Wi-Fi uses radio waves (RF), Li-Fi uses light. Lasers are waiting in the wings, according to technology proponents.

Overcoming Li-Fi limitations?

Li-Fi enthusiasts such as Cisco principal engineer John Parello point out that the technology has great potential to offload the overcrowded radio spectrum, which in its own right comes with many benefits including avoidance of network clashes that cause Wi-Fi signals to drop. They also note that Li-Fi does not interfere electromagnetically with other radio equipment such as hospital gear or factory floor robots, a key concern in those environments.

Furthermore, Li-Fi is considered more secure than Wi-Fi because Li-Fi requires line of sight, which is a big reason why the U.S. Army is using it in a couple of known locations, buying both from Edinburgh, Scotland–based pureLiFi and from Signify. An intruder cannot hack it from outside the walls of a building, because the light is blocked by walls.

But that same of line of sight is typically also regarded as a limitation. Li-Fi can only reach so far, and users must be underneath the lights and electronics that transmit it, without wandering far to either side.

But Cisco’s Parello reminds us that there is a way around that restriction.

“Typically, people think that light communication means you need a direct line of sight to the transmitter,” Parello noted in the same blog post from which we quoted last month.

It doesn’t have to be that way, he notes, citing work by the Piscataway, N.J.–based Institute of Electrical and Electronics Engineers (IEEE).

“The IEEE has been working on a standard for Reconfigurable Intelligent Surfaces (RIS) as a way to intentionally redirect radio signals in complicated deployments,” Parello said.

LEDs wrote about nascent RIS work a year ago.

Since then, efforts to develop the technology seem to have picked up. Parello references a March 2022 paper published by IEEE detailing the technology’s potential. The paper’s authors include Harald Haas, who is regarded as the “father of Li-Fi.” Haas cofounded Li-Fi pioneer pureLiFi in 2012 and continues to serve as chief scientific officer, while also wearing many other hats. He is distinguished professor of mobile communications at the University of Strathclyde in Glasgow; he is the director of the university’s LiFi Research and Development Centre; and he is an advisor to Santa Barbara, Calif.–based Kyocera SLD Laser (KSLD), helping the company to develop laser-based Li-Fi.

While the prospect of widening a Li-Fi zone might seem to be a good thing, does it undermine the inherent security benefit? In the paper we cited last summer, the authors — again, including Haas — noted to the contrary.

As we wrote then:
“They claim that RIS-equipped Li-Fi environments ‘can lead to enhanced physical leader security’ in several different ways. For example, somehow an RIS system can detect intruders, and then emit artificial noise in the intruder’s direction as a jamming technique. RIS elements can be precoded in a way that only legitimate users can decode, the authors state.”

Cisco’s Parello seems to convey something similar.

“With Li-Fi, it’s possible to direct data at targeted devices,” he said. “You can create a wireless network that only works with devices you designate, allowing for an ‘intentional’ approach to network design. Radio waves don’t offer this type of precision.”

Prospects for commercial application

This detail could finally launch Li-Fi into the mainstream. The technology’s gestation period has been a long one, which has been hindered by a standards debate as well as by gadget makers’ reluctance to embed the technology into devices.

Some Li-Fi supporters believe lasers will make the difference by providing huge speed advantages compared to Li-Fi and Wi-Fi, as demonstrated by KSLD earlier this year.

PureLiFi recently received £10 million from the Scottish government to further develop Li-Fi.

Follow the links in this story for more of the trials, tribulations, and future of the communications technology and application.

MARK HALPER  is a contributing editor for LEDs Magazine, and an energy, technology, and business journalist ([email protected]).

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