Wireless Performance

Starting with this review, I am now using a standard test client for all wireless LAN testing, instead of using a "manufacturer-recommended" client with each router. I am doing this because:

• Most people go shopping for routers, not clients
• Many people don't buy "matched" clients to go with their routers, especially since most notebooks come with built-in wireless adapters
• Using different clients introduced another variable into the performance equation

After a search that included the criteria described in A Good Draft 11n Client is Hard To Find, and input from a helpful reader, I settled on the Intel Wi-Fi Link 5300 AGN mini-PCIe card as the new SNB standard wireless test client. Unlike Intel's 4965AGN mini PCIe draft 802.11n adapter, the 5300 allows 40 MHz channel operation in 2.4 GHz (although it is disabled by default). It also meets the other selection criteria including dual-band and WPS support.

It turns out that it also has a feature that wasn't on my original selection list: three stream operation. So when the 450 Mbps routers introduced by D-Link and TRENDnet at this year's CES ship later this year, I'll be ready for them.

The router had 1.21 firmware and I left all factory default settings in place, except for setting Channel 1. On the Intel client side, I left all defaults in place except for enabling throughput enhancement (packet bursting). This article describes the entire wireless test setup.

Figure 5 shows the summary of up and downlink tests in all six test locations and with the default 20 MHz and "Auto" (40 MHz) channel bandwidth modes.

Figure 5: Six location wireless throughput summary

The good news is that the 655 reached all six locations, including my notoriously-difficult locations E and F. But the Intel client could have played an important part in this performance, which is one of the reasons that I have switched to a standard test client. Throughput in those locations, however, tended toward the barely-usable, measuring just under 3 Mbps best-case.

The highest throughput was 100 Mbps, measured running uplink with a 40 MHz channel bandwidth. This is a significant boost from the 62 Mbps running uplink with a 20 MHz channel. Best case downlink was 83 Mbps, again with a 40 MHz channel.

Figure 6 shows the summary plot of IxChariot tests for downlink tests with a 20 MHz channel width. We once again see the high throughput variation that seems to be baked into the draft 802.11n cake.

Figure 6: Wireless throughput summary - downlink, 20 MHz channel

Figure 7 shows the uplink summary for 20 MHz channel width, where variation seems a bit lower.

Figure 7: Wireless throughput summary - uplink, 20 MHz channel

Click these links for 40 MHz channel downlink and uplink plots.

There was a bit of a surprise checking the wireless security mode throughput, with slightly over 30% reduction running downlink with WPA2/AES (Figure 8).

Figure 8: Wireless security throughput - downlink, 20 MHz channel

The uplink test (Figure 9), however, showed no loss when using WPA2/AES. Both directions show the usual drop to 802.11g speeds when using either WEP or WPA/TKIP security.

Figure 9: Wireless security throughput - uplink, 20 MHz channel

I'm still building up my database of wireless performance using the six location open air tests. And I don't have open air results for the original DIR-655. So I picked the D-Link dual-band DIR-825 and Belkin N+ to run a Wireless Chart comparison.

Figure 10: Wireless comparison - downlink, 20 MHz channel

Once again, none of the products is the consistent winner in each test location. Although the combination of DIR-655 A4 and the Intel 5300 client was the only one to go the distance, literally, in all six locations, up and downlink. You'll find similar results for the 40 MHz channel bandwidth tests. Just hit the Wireless Charts and see for yourself.

Figure 11: Wireless comparison - uplink, 20 MHz channel

Closing Thoughts

The upshot of all this is that the DIR-655 A4 looks like it hasn't sacrificed performance with its cost-reduced design that enables a street price of around $100 and D-Link to presumably still make money. Its good wireless performance, stable operation, gigabit switch, high routing throughput and automatic uplink QoS continue to make it the go-to draft 802.11n router.