Wi-Fi at 10,000x less power invented

Posted on 16 Dec 2016


… engineers in the US have just generated Wi-Fi transmissions that use 10,000 times less power than conventional methods, which means you can have everything downloading all the time, without sacrificing battery life. And it can already be used with off-the-shelf smartphones.
So far, the team from the University of Washington has only managed to achieve speeds of 11 megabits per second with the new connection, which isn’t going to break records any time soon (it’s no Li-Fi).

But they’re working on getting the connection faster, and, more importantly, they’ve already shown that their ‘passive Wi-Fi’ technology works in real-world testing – it reportedly integrates “seamlessly” with existing routers and smartphones.

“We wanted to see if we could achieve Wi-Fi transmissions using almost no power at all,” says one of the team, Shyam Gollakota.

“That’s basically what Passive Wi-Fi delivers. We can get Wi-Fi for 10,000 times less power than the best thing that’s out there.”

A paper on the results is being presented in March next year at the USENIX Symposium on Networked Systems Design and Implementation.

It has yet to be peer-reviewed and independently verified, so we need to take it with a grain of salt, but the technology looks so promising, it’s already been listed as one of the top 10 breakthrough technologies of 2016 by MIT Technology Review.

So how does it work? Right now, Wi-Fi signals require information to be sent across a digital frequency, known as a digital baseband, as well as an old-school analogue radio frequency (RF).

Those two frequencies work together to send ‘packets’ of information that are decoded by your smartphone.

But while digital baseband technology has gotten a whole lot more efficient over the past few decades, allowing information to be sent using hardly any energy at all, analogue radio frequency devices have stalled, and still suck up hundreds of milliwatts of power.

That’s a problem, because to receive Wi-Fi on your smartphone, you need a digital and an analogue RF receiver, hence your phone’s crappy battery life.

The new University of Washington system overcomes that, by decoupling analogue and digital, and relegating all analogue RF functions to one single plug in device.

That plugged in device generates the Wi-Fi signal using an array of sensors, and those Wi-Fi packets are then reflected and absorbed using a digital switch known as the ‘passive Wi-Fi’ device, which runs on barely any energy at all.

The passive Wi-Fi bounces the information to your smartphone or router, where it can be received by consuming only 15 to 60 microwatts of power – 10,000 times less than current devices. … In real-world tests, the passive reflectors could communicate with off-the-shelf smartphones even at distances of 30 metres (100 feet).

“All the networking, heavy-lifting and power-consuming pieces are done by the one plugged-in device,” said one of the team, Vamsi Talla.

“The passive devices are only reflecting to generate the Wi-Fi packets, which is a really energy-efficient way to communicate.”

Not only could this save your phone’s battery life, it could also finally make that ‘internet of things’ we’ve all been hearing about so much more feasible – in the past, it would have cost huge battery life to have things like your fridge and washing machine connected…


My interest in this comes from the health risks of Wi-Fi. Even if the only negative effect was disruption of sleep (see this study) that would be worth a global change with limits on emitter Wi-Fi. With this low power way to use Wi-Fi, I hope industry will finally admit the biological non-thermal effects of microwave radiation. Current Wi-Fi devices are basically unshielded microwave radiation generators.

Posted in: Health, Technology