How Wi-Fi could get a boost from Li-Fi

Li-Fi could turn LED light bulbs into network access points

Wi-Fi has had an enormous impact on mobile computing use, enabling employees to access corporate networks from anywhere and turning coffee shops into offices for independent workers. It also has its shortcomings, which is where a new standard, Li-Fi, could one day fill in the gaps, assuming it can make it to market.

The trouble with Wi-Fi? It doesn’t travel far, especially through walls. It is notoriously insecure and easy to spoof by hackers. And even with the bandwidth increases over the years, an access point can be overwhelmed rather easily when too many people try to access it at the same time.

Throwing more Wi-Fi at the problem is at best a partial solution. It doesn’t solve the issues of security and only partially solves the scalability issue.  

Enter Li-Fi, or Light Fidelity, an emerging wireless protocol that uses visible light spectrum to provide wireless networking access. A Li-Fi transmitter uses LED lights to modulate light intensity – mostly beyond what our eyes can perceive – and that is read as data by a photosensitive receiver. Because LEDs already use a chip to control their output they can modulate lights up to millions of times per second, theoretically allowing them to transmit data up to 100 times faster than WiFi.

But Li-Fi is meant to complement, not replace, Wi-Fi. It will co-exist in devices like smartphones, tablets and laptops, using the cameras already in these devices to send and receive the Li-Fi signal from LED lights. All that’s required is a special encoder/decoder chip to convert the light signal to data.

Li-Fi remains a work in progress, but its creator says that the IEEE is currently considering it for inclusion with the 802.11 Wi-Fi standard. As the IEEE notes on the Topic Interest Group page, "The introduction of light emitting diodes (LED) for general purpose lighting has created a growing interest in using the visible light spectrum for wireless communications." But the standards body is still seeking feedback from members.

Will Stofega, program manager for mobile device technology and trends at IDC, says good luck with that.

"Getting any standard approved is tough," he says. "There is always an ecosystem and political interests to play out. I think overall it needs a lot of work, but it’s the most promising of the alternative connection technologies."

Stofega warns that people with vested interests will throw FUD on any potential disruption of their revenue stream. Just as some 4G vendors cast aspersions on 5G simply because it threatens their market dominance, Li-Fi is likely to face opposition as well.

"You can be sure the Wi-Fi forum has a white paper somewhere that says it’s a terrible idea," he says.

Spectrum crunch

Using light to transmit data is nothing new; it's how your TV’s remote control operates. But remote controls use infrared, which has severe limitations in distance and throughput.

Li-Fi was first introduced in 2011 at a TEDGlobal conference by Professor Harald Haas, Chair of Mobile Communications at the University of Edinburgh and co-founder/chief scientific officer of pureLi-Fi Ltd., the company trying to bring Li-Fi to the market.

Haas says he was inspired to create Li-Fi because of the spectrum crunch. He said he was working for Siemens on 4G when he realized the RF spectrum wasn’t enough for things like multimedia. Since then he developed the world's first Li-Fi dongle, and partnered with French lighting manufacturer Lucibel to make the first fully integrated Li-Fi luminaire, which was shown at this year’s Mobile World Congress.

"Li-Fi is where Wi-Fi is fifteen years ago, and in five to ten years, Li-Fi will be as ubiquitous as Wi-Fi is now," he claims.

Anand Oswal, senior vice president for engineering in the enterprise networking group at Cisco, says Cisco considers Li-Fi an "exciting, up-and-coming technology with a lot of potential." Cisco’s strategy is to build out the Li-Fi technology and eventually develop products, but he adds "we’re still in an exploratory phase. Cisco has not made any decisions on the products and solutions with regards to Li-Fi."

A potential area of integration for Cisco is its Digital Building program, a suite of solutions in partnership with vendors including Philips, Microchip, Cree and Molex that leverages Cisco’s Power over Ethernet (PoE) and Universal Power over Ethernet (UPoE) innovations to power enterprise lighting systems.

"The capability to convert every light in the enterprise into a medium of wireless communication is a very natural evolution of this solution," says Oswal. Cisco is collaborating with partners to explore how to integrate the technology seamlessly into Cisco’s wireless infrastructure. "That would allow the Li-Fi technology to leverage the decades of innovations in the Wi-Fi domain."

One group very interested in Li-Fi is retailers, who see it as a potential replacement for beacon technology, says Jerry Johnson, president and CEO of the Energy Management Collaborative, an energy controls and IoT solution provider. He also has seen interest from government, airports, and owners of commercial spaces and buildings who want to supplement Wi-Fi or use Li-Fi to communicate with people in meeting rooms.

EMC plans to be a reseller of Li-Fi light bulbs nationwide and has already deployed them in 80 test sites.

"I think in the future there is going to be a combination of Li-Fi and Wi-Fi, with Li-Fi taking a dominant role," he says. "Li-Fi is going to vastly improve the overall bandwidth, speed and reliability of the network, not to mention enhance our communication capabilities."

Some companies are doing tests of Li-Fi but they are keeping that information under wraps for now. He did add that EMC’s own research has shown that Li-Fi can transmit data 100 times faster than traditional Wi-Fi.

How Li-Fi works

The key difference between a regular LED light and a Li-Fi-enabled bulb is that a driver circuit in the Li-Fi bulb sends and receives wireless signals, encoding the data using different intensities of light. Some lights can be hooked up to the network by connecting a CAT5 cable, while others can receive data over a power-line connection.

LiFi creates a bi-directional link that uses a special photodetector at both ends: one in the LED light in a room and the other in the mobile device itself or dongle plugged into the mobile device. The dongle has an infrared LED which sends data back to the ceiling light. As you move around a room with multiple Li-Fi lights, the device automatically detects where the strongest signal is coming from and shifts to that light source, so the signal always stays connected and at full strength.

Haas estimates smartphones and other devices will begin to ship with the Li-Fi signal chip in two to three years but could not elaborate.

Stofega says he is not hearing any interest from mobile players in Li-Fi, but adds most of them are really focused on 5G right now.

"It wouldn’t be hard to do, it wouldn’t be very expensive, but [mobile players] will want proof the tech is played out and going to be deployed before they switch things around," he says. "I’m even seeing reluctance to go full force into 5G because they are still building out the standard."

But Li-Fi differs from Wi-Fi in several key respects, such as range, interference, and throughput. One of the limitations of the wireless spectrum is that when you go up from 2.4GHz to 5GHz, you lose range. If you go higher than 5GHz, the range shrinks even further.

Li-Fi’s range is basically limited to the range of the light source. An office light naturally covers about two to four meters but starts to weaken after that. The range problem is addressed with redundancy, Haas claims. Multiple ceiling lights transmitting wireless data will ensure coverage, even if the signal weakens after a few meters.

Theoretically, Li-Fi offers far more throughput than Wi-Fi. Haas says his company, pureLi-Fi, just published work where it showed transmission at 8 Gbps from a single small micro LED. And as it stands, the 2.4GHz and 5GHz bands are saturated with existing devices like wireless phones, Bluetooth devices, and Wi-Fi, not to mention new technologies like augmented reality, virtual reality, driverless cars and billions of IoT devices.

Because visible light is completely different from other types of RF frequencies, there is no possibility of signal interference, and it is 1,000 times larger than the entire 300 GHz radio spectrum, Haas notes, adding that the LED lights don’t even need to be bright enough to be visible to humans.

Finally, adding Li-Fi to existing devices is relatively inexpensive, says Johnson.

"The cost of that tech has dropped so fast that putting it on a device is no challenge," he says. Li-Fi will use existing device camera technology. The camera in your laptop or smartphone will do just fine, they just need the decoder chip, which has to be added to future devices. But if Li-Fi becomes part of the 802.11 specification, then the Wi-Fi chip will handle Li-Fi signaling as well.

Light industry

Haas stressed that Li-Fi is a supplement to Wi-Fi and 4G/5G, not a replacement.

"I can see it being used in streetlights as access points for smart city applications," he says. "The indicator light in your home appliances can connect these devices to the Internet via the ceiling lights, and wearables with integrated LEDs can monitor health parameters and send that data to the Internet," he says.

One of Li-Fi’s shortcomings can also be considered a strength. Because it uses the visible light spectrum, Li-Fi can’t penetrate a wall. In many scenarios that’s a problem, but for secure connections it’s an asset. Haas said people with an interest in security, particularly the military, like the idea of being able to set up a wireless network that can be locked into one room so long as the walls have no windows.

Oswal says Cisco is still in an exploratory phase with Li-Fi and has not made any decisions on what it will do commercially with the technology. He says the firm believes that the Li-Fi deployments will start in niche markets where safety and security are key.

"In my opinion, Li-Fi will achieve critical mass when the end-point ecosystem for visual light communication becomes more mature," he says. "Cisco visualizes a future where Li-Fi capable lights will be sold to enterprises that offer specific throughputs and integrate seamlessly into Cisco’s wireless architecture."

Stiff challenges

Like any new technology, Li-Fi has its challenges. At least Wi-Fi had the full support of Intel behind it. Li-Fi is being driven by a university professor in Scotland, even if he does have allies like Cisco and British Telecom, which Haas says has partnered with pureLI-FI but would not elaborate on the depth of the alliance. "Any new technology has several barriers to gaining widespread adoption," says Oswal. "However, these are often just a matter of tech advances keeping pace with consumption."

Stofega believes if the IEEE makes Li-Fi part of the 802.11 spec, that will be the clincher, because all future 802.11 chips from Qualcomm, Intel and others will support it. From there it’s just a matter of getting the LED bulbs deployed. For his part, Haas says there is news coming from IEEE on the subject but could not divulge what it was.

For Li-Fi to succeed, Oswal says it has to deliver on its promise of throughput and scale; end-point devices have to hit the market; and there needs to be a Li-Fi-enabled vendor ecosystem to build the lights.

But Jack Gold, president of mobility consultancy J.Gold Associates, is skeptical.

“Light’s been tried for years, this is not necessarily new," says Gold. "With light you can get super amounts of bandwidth, but it’s not as simple as it sounds."

Then there's the fact that Wi-Fi works well and is nearly ubiquitous. If you’ve got a technology that’s in use that works fairly reliably and you come up with a new technology to replace or supplement it, Gold says, it’s got to be better.

"Show me the problem you are trying to solve and tell me why yours is a better solution. There is still a lot of stuff that needs to be addressed I need answers to," says Gold.

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