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"PoWiFi" Could Power the Internet of Things

作者:互联网    浏览:159975    发布时间:2015-11-27 10:26:55

University of Washington (UW) engineers havedeveloped a technology that uses a Wi-Fi router—a source of ubiquitous butlargely untapped energy in indoor environments—to power devices.

 

The engineers used the Power over Wi-Fi(PoWiFi) system to harvest energy from Wi-Fi signals to power a temperaturesensor, a low-resolution grayscale camera and a charger for a Jawbone activitytracking bracelet.

“We made a system that can co-exist asa Wi-Fi router and a power source," says Vamsi Talla, a UW electricalengineering doctoral student and lead author of a paper that will be presentedin December at the Association for Computing Machinery’s CoNEXT 2015 conferenceon emerging networking experiments and technologies. "It doesn’t degradethe quality of your Wi-Fi signals while it’s powering devices.”

 

PoWiFi could help enable development ofthe Internet of Things, in which small computing sensors are embedded ineveryday objects like cell phones, coffee makers, washing machines, airconditioners and mobile devices, allowing them to “talk” to each other. Onechallenge is how to energize those low-power sensors and actuators withoutneeding to plug them into a power source as they become smaller and morenumerous.

 

The team of computer science andelectrical engineers found that the peak energy contained in untapped, ambientWi-Fi signals often came close to meeting the operating requirements for somelow-power devices. But because the signals are sent intermittently, energy is“leaked” out of the system during silent periods.

 

The team fixed that problem byoptimizing a router to send out superfluous “power packets” on Wi-Fi channelsnot currently in use—essentially beefing up the Wi-Fi signal for powerdelivery—without affecting the quality and speed of data transmission. Theyalso developed sensors that can be integrated into devices to harvest thepower.

 

In their proof-of-concept experiments,the team demonstrated that the PoWiFi system could wirelessly power agrayscale, low-power Omnivision VGA camera from 17 feet away, allowing it tostore enough energy to capture an image every 35 minutes. It also re-chargedthe battery of a Jawbone Up 24 wearable fitness tracker from 0% to 41% in 2.5hours.

 

The researchers also tested the PoWiFisystem in six homes. Users typically didn’t notice deterioration in web pageloading or video streaming experiences, showing the technology couldsuccessfully deliver power via Wi-Fi in real-world conditions without degradingnetwork performance.

 

Although initial experiments haveharvested relatively small amounts of power, the UW team believes there isopportunity for make the PoWiFi system more efficient and robust.

 

“In the future, PoWi-Fi could leveragetechnology power scaling to further improve the efficiency of the system toenable operation at larger distances and power numerous more sensors andapplications,” says Shyam Gollakota, assistant professor of computer scienceand engineering.