background scanning, like Windows XP?

The current NetBSD support for scanning is very useful, but I'd 
really like to be able to do background scanning, like Windows
XP.  That is, I'd like to be able to scan for new APs while I'm 
associated with (and sending traffic to) an AP.

The IEEE 802.11 spec has a paragraph or two about putting the
end station into power saving mode, probing and scanning
for APs on other channels while the current AP thinks we
are asleep, then returning to the original AP before the 
power saving period ends.  I'd love to do this, but it looks 
to me like, on the PRISM-2 card at least, I'd need some firmware 
support for it.

When I normally scan while associated, I only get a listing for
the currently associated AP.  I can set the NWID to the empty
string, and then scan, which will get me a full list of APs.
Alas, the card will often associate with a different AP after
the scan, so I have to reset the NWID and get it re-associated.
Plus, this seems to take at least a couple hundred milliseconds.

What am I missing?  Is there some secret incantation to get
this to work?  Does it work on FreeBSD or OpenBSD, and I've
just been too dim to notice?

Thanks,

Kevin
[email protected]
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