RF-powered computers are small devices that compute and communicate using only the power that they harvest from RF signals. While existing technologies have harvested power from ambient RF sources (e.g., TV broadcasts), they require a dedicated gateway (like an RFID reader) for Internet connectivity. We present Wi-Fi Backscatter, a novel communication system that bridges RF-powered devices with the Internet. Specifically, we show that it is possible to reuse existing Wi-Fi infrastructure to provide Internet connectivity to RF-powered devices.
From the PDF:
[W]e seek to design RF-powered devices that communicate directly with commodity Wi-Fi devices. A positive answer would pave the way for a rapid and simple deployment of the RF-powered Internet of Things by letting these devices connect to existing mobile phones and Wi-Fi APs. It would also expand the functionality of Wi-Fi networks in a new direction: from providing connectivity to existing Wi-Fi clients to a whole new class of battery-free devices.
Achieving this capability, however, is challenging since conventional low-power Wi-Fi transceivers require much more power than is available from ambient RF signals. Thus, it is not feasible for RF-powered devices to literally speak the Wi-Fi protocol. Conversely, since existing Wi-Fi devices are specifically designed to receive Wi-Fi signals, it is unclear how they would decode other kinds of signals from RF-powered devices.
(Score: 3, Interesting) by Uncle_Al on Saturday April 21 2018, @11:56PM (5 children)
So they're IoT LEECHES
Lovely..
(Score: 1, Interesting) by Anonymous Coward on Sunday April 22 2018, @12:27AM (4 children)
Funny. My mobile wifi hotspot is battery powered. I can expect much less battery life now. Thanks.
(Score: 2, Interesting) by Adamsjas on Sunday April 22 2018, @12:48AM (3 children)
Transmit power is not altered by the number of receivers. But I'm betting you know that and were going for funny.
(Score: 2, Informative) by Anonymous Coward on Sunday April 22 2018, @01:12AM (2 children)
Power is expended when an RF leech tethers to a phone and gains connectivity by causing the phone to transmit to a tower. More RF leeches means more power expended.
I'm betting you know that and you're a fucking asshole.
(Score: 1, Interesting) by Anonymous Coward on Sunday April 22 2018, @01:26AM
be nice please! lol
(Score: 2) by Osamabobama on Monday April 23 2018, @10:51PM
The power harvesting comes from relatively high power signals, like television broadcasts. There is no need, nor capability, for these devices to send power level commands to the emitter.
On the other hand, tethering to a phone to cause it to transmit more power is certainly possible, but that's not what we are talking about here. Furthermore, that tether would require some sort of communication protocol, such as Wi-Fi, but that was specifically ruled out as impractically power hungry for Wi-Fi powered devices.
Appended to the end of comments you post. Max: 120 chars.
(Score: 4, Interesting) by EvilSS on Sunday April 22 2018, @01:33AM (2 children)
(Score: 1, Interesting) by Anonymous Coward on Sunday April 22 2018, @01:50AM (1 child)
Ironically, you need some of these developments to have your decentralized meshnet.
(Score: 3, Interesting) by MostCynical on Sunday April 22 2018, @02:34AM
Don't hold yor breath!
"I guess once you start doubting, there's no end to it." -Batou, Ghost in the Shell: Stand Alone Complex
(Score: 1, Interesting) by Anonymous Coward on Sunday April 22 2018, @02:50AM (1 child)
Unless they at least produce a demo prototype, don't bother posting these "perpetual motion machine" bullshit.
(Score: 2) by Reziac on Sunday April 22 2018, @05:12AM
...a paper exploring the inverse relationship between hype and working prototypes...
And there is no Alkibiades to come back and save us from ourselves.
(Score: 2) by maxwell demon on Sunday April 22 2018, @05:00AM (2 children)
Apparently it cannot power a dept. line.
The Tao of math: The numbers you can count are not the real numbers.
(Score: 2) by janrinok on Sunday April 22 2018, @07:03AM (1 child)
(Score: 0) by Anonymous Coward on Monday April 23 2018, @09:53AM
So you're saying the editor ran out of humour?
(Score: 3, Informative) by leftover on Sunday April 22 2018, @04:07PM (2 children)
Maybe they need someone to point out the decades-old history of backscatter RFID systems (as opposed to the NFC variations) and their relative power levels vs data rates.
Bent, folded, spindled, and mutilated.
(Score: 2) by c0lo on Sunday April 22 2018, @10:12PM (1 child)
The do so in the linked PDF, at least in what they achieved with their antenna/cicuit
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 2) by leftover on Monday April 23 2018, @02:59AM
Thanks for this. The numbers are in line with what I expected. Trying to stretch the range in real-world conditions becomes troublesome. Omnidirectional antennas get slaughtered by multipath distortion with as few as one data channel. The longest-range system I worked with, for identifying railroad cars as they passed by, had to use a focused beam of non-trivial power. (Not knocking birds out of the sky like military air-search radar but too high for people to be close.) The grid-dip signal was just a static number. My bottom line is still that it does not support use for general Internet access. Round-the-clock energy collection and daily short report from a sensor, sure in cities. By the time you get far enough out to see green spaces the RF noise really drops. I don't think most people are aware just how feeble our RF links can be. Receiver technology has made astonishing gains over the past few decades, allowing transmit power to drop by orders of magnitude.
Bent, folded, spindled, and mutilated.