I have a MacBook Air mid 2012 with i7 CPU. The one with Ivy Bridge.

I have connectivity problems with wifi running Arch Linux which I keep updated regularily. Throughput and response time performance decrease a lot when I move away from the AP (tried several networks with similar results).

Strangely I don't experience the same issues with OS X. I have tried switching between Mountain Lion and Arch Linux while staying in the exact same position. OS X performs perfectly while Linux can't even ping the router.

Are there any settings that I am missing? Should I use some particular driver? I have tried to read up on and fiddle with iwconfig. 

Any suggestions are welcome, I'm quite new at this level of Linux configuration.