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: 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.