Researchers create super-efficient Wi-Fi | Hacker News Reader

Researchers create super-efficient Wi-Fi

arstechnica.com

101 pointspavornyoh13 comments

While this is interesting work, I would say it's going into the wrong direction. It is simplifying the devices at the cost of less efficient use of the already crowded radio spectrum (the plugged-in device must transmit the carrier wave and the reflections from passive devices consume twice the spectrum due to mirror frequencies) Everyone else is going the other way: complicating devices to achieve higher spectrum efficiency. This approach might be sustainable for spy agencies, but I don't see how it could scale to mass deployment (especially with device densities predicted by IoT pundits these days).

Mentioned in the article is the passive bug the Soviets used for covert listening in the US embassy in Moscow. Impressive technology for 1945: https://en.wikipedia.org/wiki/The_Thing_%28listening_device%...

The NSA ANT catalog of spy devices (leaked by Snowden) also includes cheap analog retro-reflectors: https://en.wikipedia.org/wiki/NSA_ANT_catalog

Wondering why the two passive devices have the same mac address...

Nice catch, I haven't read the paper yet but I wonder if it belongs to the device generating the frequency.

Shouldn't since the passive devices build the packets the MAC is probably the same because it's they just copied the same exact fpga code on both devices.

What wasn't clear and should be mentioned is that the active device doesn't have to transmit wifi at all it's just a source of random rf radiation at compatible frequencies since you craft packets by selective reflecting the signal.

The same researchers released a video demonstrating the basics of this (though not with WiFi) a few years ago:

https://www.youtube.com/watch?v=gX9cbxLSOkE

https://homes.cs.washington.edu/~gshyam/Papers/amb.pdf

Wonder why they chose the UK "health lottery" - quite a small lottery, vs the UK National Lottery ?

This is pretty incredible, and congrats to the research team!

But, could you please not use phrasing like "Reduces Power 10,000x". I don't think I'm the only that has an aversion to this: http://timesless.com/

http://www.xkcd.com/169/

Get over yourself.

In particular, your page of drivel goes wrong here:

> "smaller than", "less than" etc. indicate subtraction, as in: 2 less than 10 is 8.

Believe it or not, "smaller than" and "less than" are also used to refer to being smaller or lesser (go figure) in size or amount, as in "2 is less than 10".

That's pretty rude. The poster was only asking for something that would improve clarity.

> The poster was only asking for something that would improve clarity.

This is not true. There is no issue of clarity if I say "the effect of losing a leg on quality-adjusted life years is four times smaller than the effect of smoking", or at least, no ambiguity about how the two numbers I'm thinking of relate to each other (numbers wholly invented). The poster was asking us to conform to his personal peeves.

That's a pretty simple special case of English language: if a reduction is indicated by a multiplicator greater one, the result is the same as multiplying by the multiplicative inverse of the number.

So 10 reduced by factor 10,000 is clearly 10 * 1/10000 = 0.001.

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