I was all set to test the 6504n using our Azimuth-based procedures, but ran into a snag when I opened up the EW-7718Un USB adapter. I need a direct connection to the Azimuth system for both client and router, but the USB adapter's board didn't have the mini-connectors found on Cardbus adapters. Since I didn't want to risk damaging the board by trying to solder on a pigtail, I had to fall back to all open-air testing, using my five test locations.
The EW-7718Un adapter was inserted into a Fujitsu P7120 Lifebook (1.2 GHz Intel Pentium M, 504 MB) notebook running WinXP Pro SP2 with all the latest updates. I used the 126.96.36.199 Driver and Utility that came with the adapter, after checking the Edimax site for update. I used mostly Windows Zero Config for testing, but used the Edimax client utility for testing WPS.
The router had 1.32 firmware and I left all factory default settings in place, except to set Channel 1 and change to 20MHz mode from the improper Auto 20/40 MHz default.
Figure 10 shows a composite IxChariot plot of wireless uplink, downlink and simultaneous up and downlink tests with the router set to 20 MHz channel bandwidth mode. Testing was done with the router and notebook about 10 feet apart in open air sitting in my lab with no other networks in range.
The plots show top up and downlink speeds of around 75 Mbps, but with variation that lowers the 1 minute average speed to around 70 Mbps.
Figure 10: Up and downlink throughput - 20 MHz bandwidth
You can also see the highest throughput is clocked with the simultaneous up and downlink test, with a total average throughput around 86 Mbps.
Figure 11 shows a composite of test runs with the Auto 20/40 MHz mode set. I monitored spectrum use during testing with the Cognio Spectrum Expert, which confirmed that Channels 1 and 5 were used when the tests were run.
Figure 11: Up and downlink throughput - 40 MHz bandwidth
The plot shows that peak and throughput is only a few Mbps higher, with 1 minute averages around 72 Mbps for up and downlink. The simultaneous up and downlink total throughput actually came in 10 Mbps lower at 76 Mbps, primarily due to higher variation.
The bottom line here is that there is little performance advantage to be gained by running the 6504n in its 40 MHz mode. So by using the legacy-friendly mode, you can be kind to your wireless neighbors and get good throughput, too.