Chinese professor builds Li-Fi system with retail parts

The equipment is big and expensive, with the research costs at almost $500,000. But by just using retail components, Chinese professor Chi Nan has built her own Li-Fi wireless system that can use LED lights to send and receive Internet data.

"I bought the lights from Taobao," she said, referring to the Chinese e-commerce site.

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The professor from Fudan University showed off the technology on Tuesday at the China International Industry Fair in Shanghai. Unlike traditional Wi-Fi routers that use radio signals, Chi's system relies on light to send and receive data wirelessly.

 Li-Fi China System (2)

Michael Kan

Chinese professor Chi Nan has made a Li-Fi system using retail components.

Others scientists, especially in the U.K., have also been researching the technology, and dubbed it "Li-Fi". But rather than develop specialized hardware, Chi bought off-the-shelf retail parts to create her system.

Chi, an expert on optical fibers, said on the side lines of the trade show that she was simply interested in the promise of Li-Fi. "I just wanted to play around," she said. Funding also came from the local Shanghai government, which has made research in the area a goal.

While Li-Fi is still in its early stages, the technology could provide an alternative to using radio waves for wireless Internet access. Currently, household Wi-Fi routers and mobile telecommunication towers depend on radio signals to send data wirelessly. But the amount of radio spectrum is limited.

Li-Fi, however, could be deployed in everyday LED bulbs, with light-based Internet connections covering the interior of entire homes or buildings. The data connection speeds can also reach several gigabits per second. Chi's own system runs at 150 Mbps by using a small number of LED bulbs each at one watt.

"With a more powerful LED light, we can reach 3.5 Gbps speeds," she added. Both the router and receiver are fitted with LED bulbs so that they can send data, and also installed with a chip that can process the signals.

But Li-Fi isn't without its drawbacks. Because it is dependent on light, the technology can't penetrate walls or work in complete darkness. In Chi's case, the Li-Fi receiver must be within three meters of the router, and placed under the LED bulbs so that the sensor can read it.

In addition, her system is not exactly portable. The first model is quite large, with the Li-Fi receiver itself is about the size of a video game console. A second model was made to compact the parts, and that Li-Fi receiver resembles closer to a mini desktop PC. On Tuesday, the receivers were shown connected to two nearby laptops via ethernet cable.

"There are still many problems that need to be resolved," Chi said, pointing to the need to improve the Li-Fi coverage, and miniaturize the needed components.

Over time, however, the Li-Fi receiver could conceivably take the form of a USB dongle that attaches to a notebook. Chi estimates it will take another five years before the technology can enter the market as consumer products. So far, her team has spent about 18 months on the project.

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