February 25, 2016
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Wi-Fi AA

As I’m sure you’ve noticed, your smartphone’s Wi-Fi antenna is only of the biggest drains on your battery, especially when you’re constantly streaming large chunks of data from the web, such as a video. It would be great to cut down that power consumption and researchers from the University of Washington have demonstrated that it is possible to generate Wi-Fi transmission signals using 10,000 less times power than that required by conventional technologies. The team has dubbed its technology “Passive Wi-Fi” and it could become a key Wi-Fi technology in future years.

Passive Wi-Fi works by decoupling the digital and analogue operations involved in radio transmission. As it’s the analogue radio components that require so much power, the researchers moved this off into a single mains connected device that sends out a signal into a room or area. This signal is then absorbed and reflected using a digital switch on much lower power digital components, in order to send traditional Wi-Fi packets. So the power savings continue to stack up when there are more devices using the very low power components in range of a single higher power transmitter.

“All the networking, heavy-lifting and power-consuming pieces are done by the one plugged-in device. The passive devices are only reflecting to generate the Wi-Fi packets, which is a really energy-efficient way to communicate … We can get Wi-Fi for 10,000 times less power than the best thing that’s out there.” – Shyam Gollakota, UW assistant professor of computer science and engineering

The technology can transmit Wi-Fi signals at rates up to 11 megabits per second and this can be decoded on any of the billions of devices with existing Wi-Fi connectivity, including your smartphone. On the University of Washington campus, Passive Wi-Fi achieved a communication range of 100 feet (30 meters), which is certainly better than my home router.

Impressively, this means that Passive Wi-Fi can send data further while consuming 1,000 times less energy than existing low energy standards, such as Bluetooth and Zigbee. This potentially makes it not only a game changer for familiar connected devices, but Passive Wi-Fi might also open up a market for entirely new connected products.

A paper further detailing the technology with be presented in March at the 13th USENIX Symposium on Networked Systems Design and Implementation in California.

Robert Triggs
Lead Technical Writer at Android Authority, covering the latest trends in consumer electronics and hardware. In his spare moments, you'll probably find him tinkering with audio electronics and programming.