

Speed is hard [pdf] - 2510c39011c5
http://mirror.csclub.uwaterloo.ca/csclub/speed-is-hard-at-uwaterloo.pdf

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bsdetector
> Wireless is way too slow

Way too slow for gigabit internet, not way too slow for what most people
actually need.

T-Mobile LTE in one city had an average of 28 Mb/s, enough speed for Netflix
4k, and 95 Mb/s max observed speed. I hate to support cable monopoly arguments
in any way, but really for most people 100 Mb/s _is_ overkill.

Of course the cell network couldn't support everybody's internet use with the
towers covering such a wide area as today, but wouldn't fiber to the
neighborhood and then wireless within it make a lot more sense than running
expensive cable to every individual house? It wouldn't be gigabit, but if I
could use uncapped tethering (due to smaller tower coverage area) that would
be fine with me. T-Mobile LTE is plenty fast enough for anything I use the
internet for.

~~~
z3t4
Lets assume you get 100 ms higher latency with wireless. And you make around
100 clicks per day. Over your lifetime, you would have lost one hour of your
life because you used wireless! When you are on the death bed you will think
about all the things you could have used that hour for instead!

Lets take it a step further and count everyone who is using wireless today,
that would be millions of hours lost. Think about what those millions of hours
could have been used for instead!

That hour might be nothing for you, but for the whole humanity, it's a lot!

~~~
jimrandomh
100ms of network latency wastes a lot more than 100ms of user time per click,
because loading a web page involves multiple round trips to the server. In the
case of HN's front page, it took about five.

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giovannibonetti
Maybe I am doing the math wrong, but I think the plot "Minor Violations of the
Laws of Physics" has the Shannon Limit 2x smaller that what it should be.
According to [1], for each 2x increase in SNR, the limit should increase in a
full Bandwith. However, when we compare the plotted values at 45db and 60db,
we see that SNR increased 15db = 5 * 3db => 2^5. That way, the limit should
increase in 5 bandwidths. But the plot increased from 300Mbps to 400Mbps =>
100Mbps. Hence the plot was made with a bandwith of 100/5 = 20Mhz, instead of
the 40Mhz mentioned.

[1]
[http://en.wikipedia.org/wiki/Shannon%E2%80%93Hartley_theorem...](http://en.wikipedia.org/wiki/Shannon%E2%80%93Hartley_theorem#Statement_of_the_theorem)

~~~
apenwarr
I'll be honest, I find this math very confusing (as I am self taught using
flakey internet resources similar to the one we're discussing :)). But my
understanding is that there is a 2x factor somewhere that affects Shannon
limit calculations. I think it might relate to the "negative frequency"
mirrored half of the fourier transform at baseband. Or maybe I'm just doing
the math wrong.

In any case, the underlying concept is correct: a 2x2 or 3x3 MIMO radio can
exceed the Shannon limit calculated for a single channel.

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z3t4
Here's an article about "speed matters" for those that don't think latency is
important.

[http://blog.codinghorror.com/speed-still-
matters/](http://blog.codinghorror.com/speed-still-matters/)

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virtuallynathan
Does QUIC help with overcoming the bandwidth delay product? Are web page loads
with QUIC enabled faster on 1Gbps vs 10Mbps?

~~~
apenwarr
The bandwidth-delay product is a limitation of physics so you can't exactly
"overcome" it. But because QUIC is implemented in userspace instead of the
kernel, assumptions the kernel makes (like "the bandwidth-delay product will
never be >= x") can be avoided in a cross-platform way, allowing for
interesting, low-cost experiments that can later feed into improved TCP
implementations (which take much longer to deploy).

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Betelgeuse90
Great read, thank you.

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amelius
Speed is hard, but low-latency is even harder.

~~~
wbkang
Did you read the pdf? It does talks about latency.

