Researchers at the University of Waterloo are working on a new technology that would be able to deploy battery-free sensors in the home using existing Wi-Fi networks.
In previous attempts to create such a technology, researchers ran into roadblocks like the need to modify existing Wi-Fi access points, challenges with security protocols, and the need to use energy-hungry components that made the concept impractical.
The new communication mechanism, called WiTAG, can be used with common Wi-Fi access points, enabling the use of regular Wi-Fi devices for reading data from smart devices. Existing products, notes the researchers, use power-hungry Wi-Fi transmitters to send their data, and thus require the use of batteries. These sensors are battery-free.
"If you look at the current sensor products, they need batteries, which nobody likes to have to change, but they will work with commodity Wi-Fi," says Omid Abari, an Assistant Professor in Waterloo's David R. Cheriton School of Computer Science. "There has been recent research which proposes approaches that don't need batteries. But while they're addressing the battery problem, they're adding another issue; it doesn't work with commodity Wi-Fi devices.
"So our approach," he continues, "combines the best of these two worlds - it is battery-free, and it works with commodity Wi-Fi devices."
WiTAG uses radio frequency (RF) signals as a power source and makes use of existing Wi-Fi infrastructures to read data from sensors without requiring the sensors to be connected to the Wi-Fi network, which makes them easier to deploy. This allows smart home technologies such as temperature sensors, light sensors, and potentially wearable devices, such as, Fitbits and those that monitor heart rate and glucose levels, to use the WiTAG system.
"One of the biggest breakthroughs is the fact that our technique works with encryption enabled," explains Tim Brecht, an Associate Professor in Waterloo's Cheriton School of Computer Science. "The prior proposed techniques for battery-free communication do not work with encrypted Wi-Fi networks, meaning that your Wi-Fi network could not use a password; which no one wants."
The researchers, who have filed a provisional patent, implemented WiTAG, and created the first prototype, are now working on a second prototype. They are also developing an app that will work with the system, and have plans to support a variety of applications.
"By having the application running on a phone without any other modification either to the phone or to the access point, we can read sensor data," said Ali Abedi, a Postdoctoral Fellow in Waterloo's Cheriton School of Computer Science. "Data can be read from things such as temperature sensors or anything you see in smart homes."
A paper describing the system, titled WiTAG: Rethinking Backscatter Communication for WiFi Networks, which was co-authored by Abari, Brecht, Abedi, and Mohammad Hossein Mazaheri, a Research Assistant at Waterloo, recently appeared in the Proceedings of the 17th ACM Workshop on Hot Topics in Networks.