Lost wifi connection

[Stefan Rutzinger <rutzi@fs.tum.de>]

Hello,

yet another problem. Randomly, my wifi card drops its connection. It seems 
to forget its setting but everything which can be found in the logs is 
shown below. It needs ifdown wlan0; ifup wlan0 to recover.

This seems to be related to the link quality because this occurs more 
often when the signal is poor. However it's annoying having to restart the 
network whenever the signal strength dropped just for a second.

# cat /var/log/messages
kernel: [  363.852630] cfg80211: Calling CRDA to update world regulatory
domain
kernel: [  374.473765] ADDRCONF(NETDEV_UP): wlan0:
link is not ready
kernel: [  375.484569] ADDRCONF(NETDEV_CHANGE):
wlan0: link becomes ready

# cat /proc/version
Linux version 3.0.0-1-amd64 (Debian 3.0.0-1) (ben@decadent.org.uk) (gcc 
version 4.5.3 (Debian 4.5.3-4) ) #1 SMP Sun Jul 24 02:24:44 UTC 2011

# lspci | grep Wi
02:00.0 Network controller: Atheros Communications Inc. AR9285 Wireless 
Network Adapter (PCI-Express) (rev 01)

Does anybody know about such a behaviour?
Stefan