Making homes smart could become easier

Friday, February 8, 2019

Making your house “smart” could soon become cheaper and easier, thanks to new technology developed by researchers at the David R. Cheriton School of Computer Science.

Their recent study describes an approach that can be used to deploy, for the first time, battery-free sensors in a home using existing WiFi networks. Previous attempts to use battery-free sensors ran into some obstacles, making the efforts impractical. These hurdles include the need to modify existing WiFi access points, challenges with security protocols, and the need to use energy-hungry components.

photo of Ali Abedi, Tim Brecht, Omid Abari and Farzan Dehbashi

L–R: Postdoctoral fellow Ali Abedi, Professors Tim Brecht and Omid Abari, master's candidate Farzan Dehbashi with the WiTAG WiFi-based backscatter system they developed (one device held by Tim Brecht and another by Farzan Dehbashi)

“If you look at the current sensor products, they need batteries, which nobody likes to have to change, but they will work with commodity WiFi,” explained Cheriton School of Computer Science Professor Omid Abari. “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 WiFi devices.”

“So, our approach combines the best of these two worlds — it is battery-free and it works with commodity WiFi devices.”

WiTAG, a system that enables backscatter WiFi communication using existing WiFi networks

WiTAG is a WiFi-based backscatter system for existing WiFi networks. It enables a battery-free tag to communicate data to existing WiFi devices without requiring any modifications.

The new communication mechanism outlined in the study, called WiTAG, could revolutionize the smart home industry as the Waterloo researchers have shown, for the first time, that battery-free sensors can be used with common WiFi access points. 
 
WiTAG will enable the use of regular WiFi devices for reading data from smart devices, unlike existing products that use power-hungry WiFi transmitters to send their data and therefore require the use of batteries.
 
WiTAG uses radio frequency (RF) signals as a power source and makes use of existing WiFi infrastructures to read data from sensors without requiring the sensors to be connected to the WiFi network, which makes them much 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,” said Cheriton School of Computer Science Professor Tim Brecht. “The prior proposed techniques for battery-free communication do not work with encrypted WiFi networks, meaning that your WiFi 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 wide 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 at the 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, 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.

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