Powering the Next billion Devices with Wi-Fi

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The UW team used ambient signals from this Wi-Fi router to power sensors in a low-resolution camera and other devices. Credit: Dennis Wise/University of Washington

The UW team used ambient signals from this Wi-Fi router to power sensors in a low-resolution camera and other devices. Credit: Dennis Wise/University of Washington

UW engineers have developed a novel technology that uses a Wi-Fi router – a source of ubiquitous but untapped energy in indoor environments – to power devices. The Power Over Wi-Fi (PoWiFi) system is one of the most innovative and game-changing technologies of the year, according to Popular Science, which included it in the magazine’s annual “Best of What’s New” awards announced Wednesday.

Researchers earlier this year show how they harvested energy fr to further improve the efficiency of the system to enable operation at larger distances and power numerous more sensors and applications,” said co-author Shyam Gollakota, assistant professor of computer science and engineering. – it doesn’t degrade the quality of your Wi-Fi signals while it’s powering devices.”

PoWiFi could help enable development of the Internet of Things, where small computing sensors are embedded in everyday objects like cell phones, coffee makers, washing machines, air conditioners, mobile devices, allowing those devices to “talk” to each other. But one major challenge is how to energize those low-power sensors and actuators without needing to plug them into a power source as they become smaller and more numerous.

They found that the peak energy contained in untapped, ambient Wi-Fi signals often came close to meeting the operating requirements for some low-power devices. But because the signals are sent intermittently, energy “leaked” out of the system during silent periods. The team fixed that problem by optimizing a router to send out superfluous “power packets” on Wi-Fi channels not currently in use – essentially beefing up the Wi-Fi signal for power delivery – without affecting the quality and speed of data transmission. The team also developed sensors that can be integrated in devices to harvest the power.

In their proof-of-concept experiments, the team demonstrated that the PoWiFi system could wirelessly power a grayscale, low-power Omnivision VGA camera from 17 feet away, allowing it to store enough energy to capture an image every 35 minutes. It also re-charged the battery of a Jawbone Up24 wearable fitness tracker from zero to 41% in 2.5 hours. They also tested the PoWiFi system in 6 homes. Users typically didn’t notice deterioration in web page loading or video streaming experiences, showing the technology could successfully deliver power via Wi-Fi in real-world conditions without degrading network performance.

“In the future, PoWi-Fi could leverage technology power scaling to further improve the efficiency of the system to enable operation at larger distances and power numerous more sensors and applications,” said co-author Shyam Gollakota, assistant professor of computer science and engineering. http://www.washington.edu/news/2015/11/18/popular-science-names-power-over-wi-fi-one-of-the-years-game-changing-technologies/