In Passive Wi-Fi, power-intensive functions are handled by a single device plugged into the wall. Passive sensors use almost no energy to communicate with routers, phones and other devices.Stock images courtesy of vector.me
With ‘Passive Wi-Fi,’ signals can be transmitted at rates up to 11 megabits/s – rates that are lower than maximum Wi-Fi speeds but are 11 times faster than Bluetooth – and decoded on any of the billions of devices with Wi-Fi connectivity. The new Passive Wi-Fi system also consumes 1,000 times less power than existing energy-efficient wireless communication platforms, such as Bluetooth Low Energy and Zigbee.
The technology has also been named one of the 10 breakthrough technologies of 2016 by MIT Technology Review. “We wanted to see if we could achieve Wi-Fi transmissions using almost no power at all,” said UW assistant professor Shyam Gollakota.
Aside from saving battery life on today’s devices, wireless communication that uses almost no power will help enable an “Internet of Things” reality where household devices and wearable sensors can communicate using Wi-Fi without worrying about power.
University of Washington computer scientists and electrical engineers have generated “passive” Wi-Fi transmissions that use 10,000 times less power than current methods. Credit: University of Washington
To achieve such low-power Wi-Fi transmissions, the team essentially decoupled the digital and analog operations involved in radio transmissions. In the last 20 years, the digital side of that equation has become extremely energy efficient, but the analog components still consume a lot of power. The Passive Wi-Fi architecture assigns the analog, power-intensive functions – like producing a signal at a specific frequency – to a single device in the network that is plugged into the wall.
An array of sensors produces Wi-Fi packets of information using very little power by simply reflecting and absorbing that signal using a digital switch. In real-world conditions on UW campus, passive Wi-Fi sensors and a smartphone can communicate even at 100 feet between them.
“All the networking, heavy-lifting and power-consuming pieces are done by the one plugged-in device,” said Vamsi Talla. “The passive devices are only reflecting to generate the Wi-Fi packets, which is a really energy-efficient way to communicate.” Because the sensors are creating actual Wi-Fi packets, they can communicate with any Wi-Fi enabled device right out of the box. “Our sensors can talk to any router, smartphone, tablet or other electronic device with a Wi-Fi chipset,” said 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 could enable entirely new types of communication that haven’t been possible because energy demands have outstripped available power supplies. It could also simplify our data-intensive worlds. eg smart home apps that use sensors to track everything from which doors are open to whether kids have gotten home from school have typically used their own communication platforms because Wi-Fi is so power-hungry.
http://www.washington.edu/news/2016/02/23/uw-engineers-achieve-wi-fi-at-10000-times-lower-power/
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