As I noted in the Linksys WRT54G2 review, I am back to using open-air tests to measure wireless performance. But I have tweaked the methodology slightly, adding a sixth test location. The new test method is described in this article. New Wireless Charts incorporating the new test method are on the way, but in the meantime, I'll have to rely on manually-generated comparison plots.
As mentioned earlier, testing was done using a Netgear WNDA3100 dual-band USB adapter 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 latest 126.96.36.199 driver and Netgear Smart Wireless 188.8.131.52 utility during testing.
The router had 1.00 firmware and I left all factory default settings in place, except to set Channel 1 for 2.4 GHz tests and Channel 36 for 5 GHz tests.
The 628's radio is essentially the same as the DGL-4500's, except only two antennas are connected. So I'll cut to the chase with two graphics that summarize most of the wireless performance story.
Figure 7 shows a composite of downlink throughput tests made at the six new test locations in the four wireless modes: 2.4 GHz, 20 MHz channel; 2.4 GHz, Auto 20/40; 5 GHz, 20 MHz channel; and 5 GHz, Auto 20/40. Each column represents the average throughput from a one minute test.
Unlike the Azimuth results, you can compare the 2.4 and 5 GHz results, since the open-air tests properly reflect the propagation and attenuation differences between the two bands.
Figure 7: DIR-628 wireless performance summary - downlink
The downlink results show suprisingly low throughput for 2.4 GHz / 20 MHz operation. So we need to turn to the IxChariot plots to see why. Figure 8 shows that even though the Location A throughput is around 50 Mbps, the high variation pushes the average down to around 37 Mbps. The same high variation is found running uplink [click for image], which also pushes down the average result.
Figure 8: DIR-628 wireless throughput detail - downlink
Figure 9 pulls together all of the uplink average test results, which appear to follow a similar pattern. Note that as with downlink, the "0" results in locations E and F for the 5 GHz band indicate a failure to connect.
Figure 9: DIR-628 wireless performance summary - uplink
To save space, I'm not going to go through the IxChariot plots for each test. But the slideshow has all the plots along with commentary.
Since I have tested this Atheros radio a few times now in previous D-Link products, I didn't run a check for wireless security mode throughput. Expect to get the same 50%+ throughput reduction if you choose WEP or WPA/TKIP security.
Mixed mode and neighboring wireless LAN performance will also be the same as we have seen before. Here's a link to the DGL-4500 review, which has the details if you need 'em.
I applaud D-Link in its efforts to make dual-band draft 11n routers more affordable. Unfortunately, it seems that the DIR-628's high wireless throughput variation prevents it from reliably delivering the blazing throughput people have been programmed (by the manufacturers) to expect from draft 11n products.
But the good news is that there is now a more affordable way for people with too many neighboring 2.4 GHz neighbors to move to the more spacious (9 non-overlapping channels vs. 3), quieter 5 GHz band. However, the reduced range of such a move might send them right back to taking their chances in 2.4 GHz and the 628 right back to the store.