19 Jan
2014
19 Jan
'14
3:31 p.m.
So the summary, and this can be bounced to them:
The AR9330 is a 1x1, single radio chain device. It's not doing MIMO.
It's doing classic fast diversity and antenna signal mixing, rather
than MIMO.
That is, there's an antenna switch that selects antenna A or antenna
B. The software can program which one to default to, and if it has
time it'll try sampling the preamble signal level on both antenna A
and antenna B before choosing which is "better".
The slow diversity (slowdiv / antcomb in the ath9k source) is where
the LNA inputs can be mixed in certain ways before being sent to the
baseband for RX processing. The configurations (from memory) are A, B,
A+B, A-B. It's not doing MIMO - there's only one radio chain and the
mixing is done via a real bonafide analog mixer. (MIMO here is where
there's much more signal analysis and correlation done in the digital
domain.)
You can actually do both on the AR9330 if you know what you're doing
and if the board is wired up the right way.
Yes, if someone pops up on the ath9k-devel mailing list and asks, I'll
do my best to make it happen.
-a