[Battlemesh] 802.11ac improvements [was: What hardware still works?]

[Juliusz Chroboczek]

>> .11ac doesn't bring any range improvements, and only marginal
>> improvements in spectral efficiency.

> Do you have any relevant data to back "only marginal improvements in
> spectral efficiency"?

Looking at the spec, the only feature I can see that improves spectral
efficiency is 256-QAM, which should give a 33% increase over 64-QAM.  And
that's only used for perfect links (MCS 8 and 9).  And it's optional.

> https://chiliproject.tetaneutral.net/projects/tetaneutral/wiki/NanoBeam
> 
> On 40 MHz channels we do about x1.5+ in PC-radio-radio-PC measured TCP
> bandwidth between n and ac, both in lab and in real links with Ubiquity
> hardware.

Interesting.  Perhaps the .11n driver doesn't implement the short guard
interval?  SGI + 256-QAM as compared to SGI + 64-QAM would be a 48%
increase, which would fit your figures.

-- Juliusz