Hi all,
I am seing the same things. Tried with several different versions of the driver - all on Windows 7, 64 bits on my Dell Lattitude E6420 with intel Centrino Ultimate-N 6300 AGN.
I can see the problem in the "Network tab" in Windows Task Manager as a dip in transferred data - in what should be a completely flat line from some HW that works with other NIC's.
Same problem is verified with "ping -t" - between a lot of 9,10,15 ms latencies I suddenly see 450 ms!
Using AirPCap I can see that just before the dip in transmission rate, the NIC is going down to less and less complex types of modulation (from MCS 7 downto 3). It would be a lot easier to read this, if only I could disable the "Short Guard Interval", as my AirPCap appears to only work with Long Guard Interval (took some time to figure that out).
So, the NIC appears to see a deteriorating signal and therefore decides to go for safer modulation-types.
After some time it goes up in speed - until it goes down again. This is repeated at rates of 10s to a minute.
Note that this happens in a VERY quiet environment for no appararent reason.
I also see that the NIC sends out power-save probes every 200 ms. I was able to get rid of that by selecting "Max Transmit Power" in the driver setup - but to no avail.
Best Regards
Klaus