Boro has that absolutely right -
If you want a read-up, wikipedia isn't too bad:
http://en.wikipedia.org/wiki/Multiple-i ... unications
http://en.wikipedia.org/wiki/802.11n#802.11n
It's also interesting to read up on the chipsets that are already coming out -
http://www.atheros-xspan.com/modules/ar ... lletin.pdf
http://www.atheros-xspan.com/modules/ar ... lletin.pdf
look like solid contenders. There are cards already shipping on the market, AFAIK.
and elsewhere there is generally a debate about how useful this is going to be in an outdoors environment. For P2MP there are advantages in non-LOS environments, and also, beam-forming capability means the power is directed to the user almost on a "per packet" basis. Some of the latest Netgear etc routers already do this, for indoor use. But for P2P links, I'm not convinced the 802.11n cards will make the link any faster, because the underlying modulation (64QAM, 40MHz channel) is the same as today's non-MIMO Atheros chipsets, and I don't think the MIMO works or gives any advantage in a P2P environment (i.e. 3 dishes pointing at each other at either end of a link).
If anyone knows more about MIMO for P2P links, please do comment/correct me -
Regards
CableFree Solutions