Trending: Amazon expands Bezos’ elite ‘S-team,’ adding 6 execs from emerging branches of the company
Passive Wi-Fi at work
UW researchers have generated Passive Wi-Fi transmissions that use 10,000 times less power than current methods. (Credit: UW via YouTube)

Computer scientists and engineers from the University of Washington say they’ve figured out a way to generate Wi-Fi transmissions using 10,000 times less power than conventional methods.

Not even low-power options such as Bluetooth Low Energy and Zigbee can match the system’s energy efficiency, based on a study to be presented in March at the 13th USENIX Symposium on Networked Systems Design and Implementation.

That level of performance has earned the UW team’s Passive Wi-Fi system a place on MIT Technology Review’s latest top-ten list of breakthrough technologies. Other technologies on the list include rocket reusability, which is being pioneered by SpaceX and Blue Origin; Tesla’s Autopilot system for autonomous driving; and T-cell-based immunotherapy, which is the focus for researchers at Seattle-based Juno Therapeutics and other companies.

Passive Wi-Fi could open the way for applications that currently require too much power for regular Wi-Fi, according to a UW news release. For example, other types of communication platforms have been required in the past for smart-home sensor systems that can detect which doors are open, or whether the kids have come home from school.

“Even though so many homes already have Wi-Fi, it hasn’t been the best choice for that,” said study co-author Joshua Smith, UW associate professor of computer science and engineering and of electrical engineering. “Now that we can achieve Wi-Fi for tens of microwatts of power and can do much better than both Bluetooth and ZigBee, you could now imagine using Wi-Fi for everything.”

That “everything” could include the Internet of Things, or IoT, a hot concept in networking that involves putting Internet-enabled sensors on everyday objects ranging from appliances to clothing. If the Internet of Things takes hold, your shirt could someday be negotiating with your washer over when it needs to be laundered.

The researchers could rev up Passive Wi-Fi to transmit standard signals at bit rates of up to 11 megabits per second, which isn’t as fast as the maximum rate for standard Wi-Fi but is 11 times faster than Bluetooth 1.0.

The secret to revving up the rate while cranking down the power has to do with digital vs. analog. The system developed by Smith and his colleagues uses a single plugged-in device for power-intensive analog functions, such as producing a radio signal at a specific frequency.

A separate array of sensors produces the Wi-Fi packets of information by reflecting and absorbing the signal, using digital switches that require virtually no energy. Prototype sensors could connect with a smartphone at distances of up to 100 feet.

“Our sensors can talk to any router, smartphone, tablet or other electronic device with a Wi-Fi chipset,” said study co-author Bryce Kellogg. “The cool thing is that all these devices can decode the Wi-Fi packets we created using reflections, so you don’t need specialized equipment.”

The technology is being commercialized through a spin-off called Jeeva Wireless, and it’s expected to go commercial within two to three years.

In addition to Smith and Kellogg, the authors of “Passive Wi-Fi: Bringing Low Power to Wi-Fi Transmissions” include Vamsi Talla and Shyamnath Gollakota. The research was funded by the National Science Foundation, UW and Qualcomm. For more information, contact the research team at

Subscribe to GeekWire's Space & Science weekly newsletter


Job Listings on GeekWork

Find more jobs on GeekWork. Employers, post a job here.