March 5, 2016


The Future of Wi-Fi Is 10,000 Times More Energy Efficient (APRIL GLASER, 03.05.16, Wired)

The student researchers invented a new type of hardware that uses 10,000 times less power than traditional Wi-Fi networking equipment. It's called Passive Wi-Fi, (you can read their paper here) and it works just like a home router, just more efficiently. To give some perspective, the state of the art in low power Wi-Fi transmissions today consume 100s of milliwatts of power, whereas the technology the student researchers developed consume only 10-50 microwatts--10,000 times lower power. 

Wi-Fi typically requires two radios to communicate back and forth, and it takes a lot of energy to discern the signal from the noise because there may be several devices using the same frequency (2.4 mHz or 5 mHz). Each device has an RF transmitter that creates a radio wave and a baseband chip that encodes that radio wave with data. With Passive Wi-Fi, instead of each device using an analog radio frequency to receive and transmit a signal, just one produces a radio frequency. That frequency is relayed to your Wi-Fi-enabled device via separate, passive sensors that have only the baseband chip and an antenna and require almost no power. Those sensors pick up the signal and mirror it in a way that sends readable Wi-Fi to any device that has a Wi-Fi chipset in it. [...]

"The low power passive device isn't transmitting anything at all. It's creating Wi-Fi packets just by reflection," says Vamsi Talla, another student working on the project. "It's a transmission technique that's ultra low-powered, as opposed to a network device."

That "reflection" happens via a process called "backscatter," and the students at UW have created Wi-Fi equipment that sends out a signal via backscatter instead of using a full radio signal.

Posted by at March 5, 2016 9:04 AM