12 ms·

I'd love to know how they got the power consumption down so low! 28microwatts when active, that's really something. Some maths: 0.000025W. A typical AA battery

• skybrian 7y ago
  From the article it says it uses backscattering and the range is not very high. I guess it would work for some devices in areas that are already blanketed with WiFi signals, though?
• roywiggins 7y ago
  This is the trick, it's using backscatter to piggy-back off nearby wi-fi signals: > The Wi-Fi radio runs on extremely low power by transmitting data via a technique called backscattering. It takes incoming Wi-Fi signals from a nearby device (like a smartphone) or Wi-Fi access point, modifies the signals and encodes its own data onto them, and then reflects the new signals onto a different Wi-Fi channel to another device or access point.
  • aneutron 7y ago
    "Knows nothing beyond what a patch antenna is" here, and I have a couple of question if you could please answer them: - Doesn't this degrade the quality of the original signal ? (i.e. some sort of destructive interference) - Isn't it illegal to interfere in signals this way ?
    • ac29 7y ago
      If this is reflecting onto a different channel (frequency) then it shouldnt interfere with the original signal (except perhaps by reducing its effective power output by a small amount). It is a general FCC rule that radios and certain other types of devices are not supposed to intentionally cause interference, but in this case there shouldn't be any. Even if there was same channel interference, its not necessarily considered intentionally harmful - for example, its not illegal to use the same WiFi channel as your neighbor as long as you are within other specified technical limits such as transmit power or antenna gain. But doing so for the express purpose of interfering with them would be.
      • aneutron 7y ago
        Thanks for the explanation !
• txcwpalpha 7y ago
  They talk about the technique in the article: > The Wi-Fi radio runs on extremely low power by transmitting data via a technique called backscattering. It takes incoming Wi-Fi signals from a nearby device (like a smartphone) or Wi-Fi access point, modifies the signals and encodes its own data onto them, and then reflects the new signals onto a different Wi-Fi channel to another device or access point. It sounds like the device doesn’t actually transmit its own signals, which I believe is what typically requires the most power. However, I get the feeling from this press release that while the WiFi chip uses less power, this does nothing to reduce the power requirements of the processing chip that is actually using the WiFi chip to communicate. In the article they use a camera as an example in the diagram. Even though the WiFi component might require less juice, you’re still going to need a hefty power supply to power the camera.
  • chubs 7y ago
    Ah thanks, that explains it. So i assume it won't work unless something else is also transmitting?
    • Polylactic_acid 7y ago
      I'm struggling to find a single use case where this would work. You need 2 wifi APs, regular wifi usage and a device where such aggressive power saving is more important than working reliably.
      • dev_tty01 7y ago
        Actually, just 1 AP. It can backscatter signals to the AP from other wifi devices such as phones. Regular wifi usage is not a constraint in most applications.
        • Polylactic_acid 7y ago
          Doesn't it say that it has to change to a different wifi channel?
      • 7y ago
• amluto 7y ago
  Backscatter. It sounds like it needs two adjacent networks. One network transmits something, and the device backscatter-modulates its signal to be received by the other network.
• deleted 7y ago
  [deleted]
• nemosaltat 7y ago
  Most batteries have shelf lives under 10 years so the typical AA probably wouldn’t last for 13 years. That said, it would be pretty incredible.
• lmilcin 7y ago
  It is incredible, but you also need to remember to be able to transmit the device needs more, sensors, processing power, etc.