I'm currently testing Dell E5510 laptops with Intel Centrino Ultimate-N 6300 (802.11a/b/g/n) adapters installed and running Windows XP Professional (SP3). Whilst the laptops can successfully associate to the network at 270 Mbps (300 Mbps if I configure Short Guard Interval), the actual throughput does not go above 96 Mbps (AT BEST). During the testing we disabled the 2.4 GHz radio's, conducted spectrum analysis to ensure a clean channel (noise free primary and seconday channel for 5 GHz 40 MHz mode) ensured that 40 MHz channels were configured and confirmed association rates at 270 Mbps during testing.
We have the latest drivers installed and have also tried earlier drivers with no luck. As a side test, I installed Netgear 802.11n USB adapters in a different laptop and confirmed that they can achieve more than 130 Mbps over the same infrastructure and with the same tests. However, the same USB adapters installed in the Dell E5510 are maxing out at 96 Mbps, the same as the Intel 6300 adapters - weird!
The test utilities used for this were Chariot (High_Performance_Throughput and Filesndl scripts), as well as iPerf, all of which produce a maximum of 96 Mbps. Wired side testing with the same client devices (and the same infrastructure) achieves between 600 - 700 Mbps, proving no bottlnecks in the wired infrastructure which is also completely isolated from any other network devices.
I'm interested in knowing if anyone else has come across similar issues with the Dell E5510 laptops, particularly with Windows XP Professional and/or similar issues with the Intel Centrino Ultimate-N 6300 (802.11a/b/g/n) adapters. If so, has anyone found a workaround?