Passive WiFi uses 10,000 times less power in mobile devices

mobile low battery

Recent research from the University of Washington outlines how a Passive WiFi system could lead the way for mobile devices and communication platforms to their reduce energy use by the thousands.

The study into WiFi transmissions discovered that Passive WiFi could allow mobile devices to use as much as 10,000 less power than standard methods. It also found that it can be applied to use 1,000 times less power than current energy-efficient platforms such as Bluetooth LE and ZigBee.

The technology could also improve the speed of communication platforms in business or school environments. A passive WiFi system requires tens of microwatts of power, and can transmit transmit megabits 11 times faster than Bluetooth, at a rate of 11 megabits per second. It can communicate over a distance of up to 30m (100 feet) in real-world applications.

Transmissions feature both digital and analog technology. Researchers cut the substantial milliwatts of power used by the analog component by assigning it to a single device plugged into an outlet. The signal sent out is therefore reflected by the remote device with its own data added to it, in the same way RFID chips use backscatter communication. 

The power-consuming and networking being managed by the in-wall device means passive WiFi devices have only a digital base band, and reflect and absorb from the signal from the in-wall device to create the WiFi packets of info.

The study’s co-author Bryce Kellogg, electrical engineering doctoral student at the University of Washington, said its Passive WiFi sensors can communicate with any device with a WiFi chipset: "All these devices can decode the WiFi packets we created using reflections so you don't need specialised equipment."

Passive WiFi could possibly have a dramatic impact on the future of the Internet of Things, significantly reducing the costs of powering devices and wearables.