The Internet of Things might as well be called the Internet of Batteries.
Internet-connected sensors that go off when the front door opens or the oven heats up may be useful, but they become a hassle when the batteries that power those components start to die.
A team of computer scientists and electrical engineers at the University of Washington may have found a way around the problem with a technology that dramatically reduces the amount of power needed to emit a Wi-Fi signal.
In research to be presented at a conference next month, team members say they have developed a technology, called passive Wi-Fi, that allows devices to communicate using 10,000 times less power than traditional Wi-Fi transmissions.
That, they say, could open the door to using Wi-Fi as the connective tissue linking smartphones or computers with the growing roster of Internet-connected devices in homes and manufacturing plants.
“One of the reasons why the Internet of Things hasn’t taken off is once you deploy sensors in your home, who’s going to replace the battery every year?” said Shyam Gollakota, a professor in the Computer Science and Engineering Department and an author of the paper. “You just want to deploy it and not think about it for 20 years.”
Gollakota’s colleagues in the project are fellow professor Joshua Smith and doctoral students Bryce Kellogg and Vamsi Talla. Their research was funded by the National Science Foundation, the University of Washington and Qualcomm, the San Diego-based mobile chip maker.
A traditional Wi-Fi radio includes both digital and analog components. The digital side, after decades of improvements in design, is energy efficient. The analog components aren’t.
As a result, Wi-Fi-connected devices require batteries or a connection to a power source.
Passive Wi-Fi achieves its smaller power footprint by removing the analog components from the device entirely, its designers say.
In a passive Wi-Fi system, a single, routerlike device connected to a power source broadcasts a signal. Nearby battery-free devices use those radio waves as fuel, absorbing and selectively reflecting parts of them back in the form of chunks of data readable by any Wi-Fi-enabled device.
In prototype tests at the UW, Gollakota and his colleagues have shown such reflected, low-power Wi-Fi transmissions have communicated with devices 100 feet away.
The team got a boost this week when the MIT Technology Review recognized its work in its list of 10 breakthrough technologies. It’s a bit of validation for years of research into such “backscatter communication” by Gollakota and Smith, a former Intel researcher.
The group is working to test the market for its innovation with its startup, Jeeva Wireless, which is licensing the technology from UW. Gollakota said the group is targeting getting its Wi-Fi technology into commercial products within two years.
“We are finally at the place where we are confident about the technology,” Gollakota said. “We know we want to commercialize this. That’s really exciting.”
