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Power Wireless Networking

Harvesting Wi-Fi Backscatter To Power Internet of Things Sensors 138

Posted by Unknown Lamer
from the energy-everywhere dept.
vinces99 (2792707) writes "Imagine a world in which your wristwatch or other wearable device communicates directly with your online profiles, storing information about your daily activities where you can best access it – all without requiring batteries. Or, battery-free sensors embedded around your home that could track minute-by-minute temperature changes and send that information to your thermostat to help conserve energy. This not-so-distant 'Internet of Things' reality would extend connectivity to perhaps billions of devices. Sensors could be embedded in everyday objects to help monitor and track everything from the structural safety of bridges to the health of your heart. But having a way to cheaply power and connect these devices to the Internet has kept this from taking off. Now, University of Washington engineers have designed a new communication system that uses radio frequency signals as a power source and reuses existing Wi-Fi infrastructure to provide Internet connectivity to these devices. Called Wi-Fi backscatter, this technology is the first that can connect battery-free devices to Wi-Fi infrastructure. The researchers will publish their results at the Association for Computing Machinery's Special Interest Group on Data Communication's annual conference this month in Chicago. The team also plans to start a company based on the technology. The Pre-print research paper.
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Harvesting Wi-Fi Backscatter To Power Internet of Things Sensors

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  • What was old... (Score:3, Interesting)

    by Anonymous Coward on Tuesday August 05, 2014 @12:25AM (#47604739)

    ...is new again:

    http://en.wikipedia.org/wiki/The_Great_Seal_bug

    Nice to see the idea being put to a less nefarious use. :)

  • Re:Sponsors (Score:5, Interesting)

    by viperidaenz (2515578) on Tuesday August 05, 2014 @12:28AM (#47604745)

    That's actually how the NSA snoop on monitor cables.

    They attach a device that looks like an EMI suppression choke that taps in to the red wire on a VGA cable. They use a microwave transmitter/receiver and the amount of RF it reflects back is based on the signal on the wire.
    Doesn't need batteries and doesn't transmit any thing so you can't detect it.

    The only difference here is the use of WiFi as the RF source.
    I don't see how they can patent something that's been done since at least 2008 by the NSA. It's the same idea except ".... over WiFi". Like all those "... on a computer" patents...

    It's described here
    http://en.wikipedia.org/wiki/N... [wikipedia.org]
    Item 35, RAGEMASTER

  • by skids (119237) on Tuesday August 05, 2014 @12:46AM (#47604819) Homepage

    Really the wristwatch is a silly example; there are better ways to harvest energy on a wristwatch than RF leaching. Stationary objects that can't rely on kinetic energy harvesting could utilize this technology, though.

    Anyway, they did test for the interference potential of this, and it was indeed very little at the rates/distances acheived.

    I think they should see how much they could *increase* the effect of the reflection on WiFi signals. Then they could look to market passive devices that, instead of being purposed for the "internet of things", are purposed to work in cooperation with MIMO/spatial multiplexing to dynamically adapt the RF environment to increase the overall bandwidth of WiFi devices, allowing an access point to turn them on and off until it gets just the right reflections. Then license that to WiFi vendors to sell them lithographed by the thousands into wallpaper or just thrown helter skepter on top of drop ceiling tiles.

  • Re:iFind (Score:5, Interesting)

    by ljw1004 (764174) on Tuesday August 05, 2014 @02:08AM (#47605029)

    It's very different from iFind...

    This paper flat out says that it's impossible to harvest enough energy from RF sources to power any kind of radio transmitter. Instead, it takes advantage of the existing idea that although you can't transmit your own signals, you can at least selectively block or intefere with someone else's RF signals. And the paper's clever invention is to apply this known technique to wifi in particular, so as to work with off-the-shelf wifi routers.

    By contrast, iFind claimed it could harvest enough energy from RF to power a bluetooth transmitter.

  • Wonderful (Score:5, Interesting)

    by sjames (1099) on Tuesday August 05, 2014 @02:16AM (#47605059) Homepage

    Oh great. You take a walk during lunch because you're concerned about your health. You stop to re-tie your shoe. Too bad your watch tattled that you just paused in front of a 'bookstore' that sells gay porn.

    Suddenly you get spammed with offers for gay porn. It's also too bad your employer was exempted from EOE because it's against the corporation's sincerely held religion, so you get fired in the process.

    Sadly for you, as you take that long walk back to your parking space you pause a gain (you'll never learn!) next to a fast food joint. By the time you get home you have an e-mail informing you of the increase in your health insurance premium.

    The internet of things could be interesting if those things would report to a server that I own and control. Too bad most corporations make internet enabled things report to them so they can sell your personal information to the highest bidder with no questions asked.

  • Re:Sponsors (Score:5, Interesting)

    by SuricouRaven (1897204) on Tuesday August 05, 2014 @04:27AM (#47605331)

    Further than that. The Great Seal bug - widely considered one of the most audaciously planted listening devices of all - operated on the same idea. It used vibration - ie, sound - to mechanically modulate a reflected radio signal. No electronic components required at all.

  • by SuricouRaven (1897204) on Tuesday August 05, 2014 @04:31AM (#47605343)

    Tesla had a long-range high-power transmission system up and running. It just wasn't commercially viable - the transmission losses were so huge, you'd have to pump in orders of magnitude more energy than you get out at the other end. There are some impressive photos of him standing by light bulbs in a field, powered by a transmitter many miles away - but not shown is the sizeable power station he had hooked up to run the thing.

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