What Is Li-Fi, and Will It Replace Wi-Fi?

Mobile communications professor Harald Haas has theorized about using LED bulbs to transmit data for years. Now, the technology is a reality.

The latest Li-Fi prototype (pureLiFi)
smithsonian.com

If Harald Haas is right, in just a few years we’ll all be getting internet through our lightbulbs.

Haas, a professor of mobile communications at the University of Edinburgh in Scotland, has been championing the idea that data can be transmitted through LED lightbulbs for years. Now, he has created a working model of a “Li-Fi” system.

In a recent TED talk, Haas demonstrated one of these Li-Fi prototypes, transmitting a video from a store-bought LED lamp to a solar cell to a laptop.

“Li-Fi is essentially the same as Wi-Fi, except for a small difference—we use LED lights around us to transmit the data wirelessly as opposed to using radio,” Haas says.

Traditional Wi-Fi uses radio signals to transmit data to devices, such as phones and laptops. Currently, Wi-Fi carries about half of the world’s internet transmissions. This percentage is expected to grow in coming years as more people get online and as the “Internet of Things” (objects with internet connectivity, from remotely programmable coffee makers to smart cars) expands. Some experts, including Haas, worry that this will create a so-called “spectrum crunch,” where Wi-Fi networks slow under heavy demand.

“Radio spectrum is not sufficient,” Haas says. “It’s heavily used, it’s very crowded…we see that when we go to airports and hotels, where many people want to access the mobile internet and it’s terribly slow. I saw this coming 12, 15 years ago, so I thought ‘what are better ways of transmitting data wirelessly?’”

The idea of transmitting data through the visible light spectrum is not new. Alexander Graham Bell transmitted sound via a beam of sunlight in 1880 using a photophone, a sort of solar-powered wireless telephone. In the past several decades, a number of researchers have looked at using visible light to transmit data.

But what Haas seized on—the key to Li-Fi—is the use of simple LED lightbulbs for data transmission. When Haas first started looking at alternative wireless systems, LED bulbs were becoming more widespread in homes, thanks to their energy savings over traditional incandescent bulbs. LED bulbs are controlled by a driver, which can rapidly dim the light or turn it on or off. Therefore, Haas figured, data could be encoded in subtle shifts of the light’s brightness, shifts imperceptible to the human eye.

So Haas and his students began to experiment with an IKEA lamp, replacing its incandescent bulb with an LED bulb. Eventually, they created a working transmitter and receiver system with the lamp and a solar panel. Fittingly, their research was done in a University of Edinburgh building named after Alexander Graham Bell, who was born in Scotland.

Li-Fi stands to be much faster than Wi-Fi. In recent experiments, researchers have been able to reach Li-Fi speeds as fast as 224 gigabits per second. At these speeds, a person could download nearly 20 full-length movies in a single second. According to Haas's research, Li-Fi can achieve data density 1,000 times greater than Wi-Fi, because Li-Fi signals are contained in a small area, as opposed to the more diffuse radio signals. 

In addition to being faster than Wi-Fi, Li-Fi will be more secure, Haas says. While Wi-Fi signals can pass through walls (allowing your neighbors to “share” your connection), home Li-Fi signals can be kept indoors by drawing the curtains. The system wouldn’t mean having to keep your lights on all the time either, Haas says—bulbs could be dimmed to such a point that they appear off, but still transmit data.

Now, Haas’ company, pureLiFi, has begun mass producing Li-Fi routers for a limited corporate clientele. They hope to bring them to a widespread market in the next several years. Li-Fi could make its way into business and industrial uses in the next two years or so. From there, it might not be long until it finds its way into homes. The system can easily network any device with an LED light—an electric kettle, an oven. Ultimately, this could bring about the Internet of Things era much faster. Haas also sees Li-Fi as a way to bring internet to remote locations, using hilltop transmitters and rooftop solar panels. LED streetlights could even be used to form a network of outdoor Li-Fi, making it possible to stay connected when walking around the city.

Just how quickly Li-Fi could spread remains unclear. "Li-Fi technology thus offers numerous benefits but there are certain barriers that must be overcome before it becomes a ubiquitous part of our lives," write researchers from St. Xavier's College in Kolkata, India. These barriers include the fact that Li-Fi becomes less powerful when light is blocked, whether due to fog or other conditions. Nevertheless, the paper says, the Li-Fi industry is slated to be worth $6 billion by 2018. 

Haas and his team aren’t the only people experimenting with Li-Fi. Chinese researchers have developed a basic Li-Fi prototype as well, powering several laptops with one LED bulb. The Fraunhofer Institute, a German research organization, has been working on Li-Fi hotspot prototypes as well. Even NASA recently announced plans to study Li-Fi’s potential uses in space travel.  

“The incandescent lightbulb delivers illumination,” Haas says. “In 20 years, the [LED] lightbulb will deliver hundreds of applications."

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