I am doing some research in 802.11 scanning at my university. At the
moment I am measuring the delays involved in different scanning
mechanisms (with a view to speed up scanning for VoWLAN's).
All clients I have tested use active scanning whereby the client will
switch between channels broadcasting probe requests and listening for
probe responses. This (on average) suspends data transfer for ~250ms.
However, I am interested in how background scanning in Madwifi works.
The Madwifi documentation here
(http://madwifi.org/wiki/ChipsetFeatures/BackgroundScanning) seems to
suggest that "iwlist ath0 scan" or "wlanconfig ath0 list scan" will do
background scanning. However, these commands seem to simply print out
an outdated list of seen AP's. Can anyone explain what background
scanning is and if it's implementedd in Madwifi?