Throughput vs. Range
As noted earlier, I couldn't use the Azimuth system to run my usual throughput vs. path loss plots. So the plots below represent throughput vs. actual range, for the five test locations around my home.
Figure 14 shows downlink test results, with high variation in Locations 1 and 2, which seems to indicate some rate switching, especially in the Location 2 plot. Location 3 throughput is the steadiest, measuring around 18 Mbps.
I'm not really surprised about the poor showing in Locations 4 and 5, which seem to defeat efforts by most wireless products to operate. While the connection stayed up in both locations, throughput was so low as to be unusable.
Figure 14: Throughput vs. Range - Downlink
Figure 15 shows uplink tests. Location 2 seems to again indicate rate switching, which takes around 30 seconds to find the optimum setting, and this time Location 3 also looks like it causes the same effect. Location 4 once again turns in unusuable throughput, but Location 5 fares a little worse and is unable to complete the test.
Figure 15: Throughput vs. Range - Uplink
Note that all testing was done with the router in 20 MHz bandwidth mode. Given the earlier testing, I wouldn't expect using Auto 20/40 mode to improve the results.
If you use the path loss to distance conversion method that I came up with, you can do rough comparisons with other draft 11n products using the Wireless Charts. Locations 2 and 3 have between 80-90 dB of Path Loss, which tends to fall somewhere on the "waterfall" portion of most products' throughput vs. path loss curves. So that would account for the range switching seen in Location 3.
The location 4 and 5 results would tend to indicate a sharper waterfall and earlier disconnect, especially in the uplink direction. This seems to be performance similar to the Belkin N1 and D-Link DIR-655, whose plots stop abruptly at around 103 dB of path loss.
In other words, the 6504n doesn't seem to have the range that some other draft 11n products have, with a shorter reach running uplink than down.