> Wi-Fi signal strength decreases at an exponential rate as you move further away from a router.

This is surprising to me. I'd have guessed it decreases quadratically (i.e. due to the inverse square law), not exponentially.

The paragraph below seems to contain an explanation, but I don't really understand it (namely because I don't know what that percentage "Coverage" column actually means, or what we mean with "the total distance at each QAM step").

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niobe an hour ago | parent | next [-]

So that table is using distance as a proxy for signal to noise ratio. SNR is what really matters.

Each data rate in the standard uses a different encoding technique. "Faster" encoding techniques cram more data into a given transmission interval but require a higher signal to noise ratio to be received without error. Since SNR declines with distance you can have a rough idea at what distance from a transmitter you will be able to receive at what data rate.

However, people and vendors focus far too much on maximum throughput. I've seen data showing that even in the best conditions, clients spend about 1% of their time transmitting or receiving at the highest data rates. Because they are dynamically adjusting the data rate based on the perceived SNR.

Individual clients' peak throughput also works against _aggregate_ throughput when talking about wireless networks with multiple users. If you have 100 clients, do you want one to be able to dominate the others or everyone get a more or less equal share? These peak speeds assume configurations that I would never deploy in practice, because they favour individual users and cripple aggregate throughput - things like 160 MHz wide channels.

But the sticker speed is what sells..

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2 hours ago | parent | prev | next [-]

[deleted]

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esafak 2 hours ago | parent | prev | next [-]

https://en.wikipedia.org/wiki/Power_law

Because the variable is the base, not exponent.

	▲	anyfoo 2 hours ago \| parent [-]
		I know what "exponentially" means, I know what "quadratically" means (and how it's not exponentially), and I know the inverse square law. Hence my question why the article claims "signal strength" decreases exponentially, when the raw power received by an antenna definitely decreases quadratically, not exponentially. That's just physics. But there might be some convoluted thing about stepping down symbol rate which affects throughput (which I guess could be colloquially called "signal strength" if I squint really hard) that I don't understand here.

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wonnage 2 hours ago | parent | prev [-]

yeah, it's pretty common to refer to x^2 as exponential colloquially since there's A. an exponent B. a single term for all values (vs. quadratic, cubic, quartic...)

But you're technically correct!

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anyfoo 2 hours ago | parent | next [-]

I'm actually not sure that they don't actually mean exponentially. There's something about not only increasing the distance, but potentially also the modulation (and thus the symbol rate) stepping down, which maybe in total causes the decline to be ~exponential? But it's not clear to me at all. That's why I ask, I have a hard time parsing it.

But then again, the sentence uses the term "signal strength", not "throughput", so that would suggest quadratically. But I guess "signal strength" could be meant colloquially and mean more than just the raw signal power received by the antenna, here.

It's all very fuzzy to me, as it stands.

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amluto 2 hours ago | parent | prev [-]

Do you also think that f(x) = x^1 is exponential? How about f(x) = x^0?

	▲	anyfoo 2 hours ago \| parent [-]
		Kind of irrelevant, because you could also ask "Do you also think that f(x) = x^1 is polynomial? How about f(x) = x^0?" The distinction was clearly between polynomial (specifically quadratic) and exponential, leaving those trivial cases out.