slow/weak wifi atheros AR9285 ubuntu 12.04

Dear Ubuntu Team,
I am getting a very poor performance from my atheros AR9285 device on ubuntu 12.04. Even if I am right next to the AP the signal strength is only 3/4 bars and the wifi performance is slow. If I go just a few metres away to my living room then the signal strength rapidly drops to the point where I can barely connect. When I boot up my computer in windows I have no problems and the signal strength and performance is very good anywhere in my apartment. This means that the problem is not hardware related but connected to the ubuntu OS or ubuntu driver.
When I first installed ubuntu on my computer i couldn't connect at all through wifi until I saw some articles which said to create '/etc/modprobe.d/ath9k.conf' and add this line 'options ath9k nohwcrypt=1' to it. This fixed part of the problem as I can now connect/work via wifi. However the performance is still bad. I am forced to use windows most of the time as I can't connect via wifi on ubuntu unless I am in the same room as the AP(and I hate using windows...).
Please help me fix this problem.
Thanks,
Noam