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Wi-Fi is a surprisingly brutal energy monster; as an increasing number of devices rely on constant connections to cloud services, its draw on global power -- not to mention your own smartphone battery -- is immense, and growing.

But now a team of researchers has found a way to push the energy efficiency of Wi-Fi to the limit, reducing the energy expense by 10,000 times.


'Passive Wi-Fi', as described by the University of Washington team behind it, is designed to consume virtually no energy while maintaining transfer speeds of up to 11 megabits per second. That's 11 times faster than Bluetooth, even while remaining 1,000 times more energy efficient than Bluetooth Low Energy.

In a paper describing the tech, co-author Shyam Gollakota writes that the aim was "to see if we could achieve Wi-Fi transmissions using almost no power at all".

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To do it, the team found a way to take the power-hungry elements of Wi-Fi, which mostly comprise the need to produce signals at the right frequency, and crunch them down to be housed in a single device plugged into a wall. This signal is picked up and relayed using almost no power by a passive device, which itself can be located up to 100 feet away from the target computer or smartphone.

The result is that instead of multiple power-hungry stages receiving and sending signals in sequence, most elements in the chain are able to operate without using power. In practical terms that makes it possible for Wi-Fi to power many more types of devices, and could allow the so-called Internet of Things to operate on standard wireless networks, not proprietary tech or Bluetooth.

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


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The team's research, which was funded by the US National Science Foundation, the University of Washington and Qualcomm, will be presented in full next month at the USENIX Symposium on Networked Systems Design and Implementation.

Meanwhile other researchers are also searching for a more efficient, or less power-intensive successor to Wi-Fi. One such project would see internet data streamed via LED lights, designed to pulse imperceptibly fast and deliver data to any device tuned to notice those variations. Harald Haas, professor of engineering at Edinburgh University, demonstrated one such 'LiFi' system at a TEDSalon in late 2015, showing that it was possible for LiFi to operate at speeds up to 50MB per second and could be on the market by 2018.