Researchers promote battery-free Wi-Fi technology

A research team at the University of Washington pushes forward with technology that uses radio frequency for power

By , IDG News Service |  Mobile & Wireless

The coming Internet of things (IoT) revolution may not run on batteries, but on power plucked from the air, according to researchers at the University of Washington.

More specifically, a university computer science and engineering team will present a paper this month on a technology called Wi-Fi backscatter, a new communication system that uses radio frequency signals as a power source. Wi-Fi backscatter devices would harvest power from ambient RF signals including TV, cellular and Wi-Fi transmissions.

The Wi-Fi backscatter devices incorporate ambient backscatter technology, which uses antennas to pick up RF signals and convert them to electricity. The university researchers said they have built on this technology with a communications system that holds the promise of connecting "billions" of devices to the Internet while avoiding the pesky, longtime problem with limited battery power.

The technology has the potential to be "a very big deal," said Bryce Kellogg, a doctoral student in electrical engineering and co-author of a paper on Wi-Fi backscatter. "One of the biggest problems with connecting the next billion devices to the internet ... is the nightmare of charging or swapping batteries for all of them."

Traditional Wi-Fi devices are "very power expensive," Kellogg said. But Wi-Fi backscatter could "greatly reduce dependence on batteries and maybe even get rid of them and harvest energy for many devices," he added.

The University of Washington team developed an ultra-low power tag prototype with an antenna and circuitry that can be connected to a variety of electronic devices. The tags can talk to Wi-Fi-enabled laptops or smartphones, while consuming negligible power.

The tags monitor Wi-Fi signals moving between routers and laptops or smartphones. The tags encode data by either reflecting or not reflecting the Wi-Fi router's signals, making a small change in the wireless signal. Wi-Fi enabled laptops and smartphones then detect these small changes and receive data from the tag.

By exchanging data through the Wi-Fi signal changes, devices like smart watches could download email from laptops or smartphones or send information tracking your morning workout back to those larger devices, the researchers said.

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