U.S. Robotics 802.11g Wireless Turbo Multi-function Access Point reviewed

Wireless Security

Next check was to see if enabling WEP caused any throughput degradation. I ran a Condition 1 (best case) test with 128 bit WEP enabled and disabled and found an decrease in average throughput of only 4%, which I consider to be within the bounds of my measurement accuracy. This is basically what I expected, since the TI chipset includes a hardware encryption co-processor to handle the tougher encryption that will be required in WPA2. The feature also ensures that enabling WEP has negligible effect on throughput.

Turbo mode

Although I knew that USR's 11g line wouldn't come anywhere near TI's over-hyped 100Mbps number, I ran a good number of tests to determine exactly how much TI's "802.11g+" / "packet aggregation" technology improved throughput. Figure 8 shows a comparison of the following tests run with a USR5410 card:

  • AP default (Dot11mode = mixed, 4x mode = Enable)
  • 4x mode disabled
  • Dot11mode = G only and 4x mode disabled.

USR5450: "4X" effect comparison

Figure 8: "4X" effect comparison - USR5410 client
(click on the image for a full-sized view)

See any difference? Me neither. But I did find that enabling 4x mode helped throughput for TI-based 802.11b+ clients, as Figure 9 illustrates.

"4X" effect comparison - D-Link DWL-650+ "802.11b+" client

Figure 9: "4X" effect comparison - D-Link DWL-650+ "802.11b+" client
(click on the image for a full-sized view)

Figure 9 contains three test runs and shows that I needed to disable "4x" mode on both AP and client in order to get the lower throughput.

Tip TIP: I found I had to completely uninstall my old driver and client utility for the D-Link card and do a fresh install of the latest ones that I downloaded from D-Link's support website. Otherwise I could get only about 600kbps throughput when I was occasionally able to connect to the AP.

802.11g Wireless Performance Test Results

Test Conditions

- WEP encryption: DISABLED
- Tx Rate: Automatic
- Power Save: Disabled
- Test Partner: USR5410 CardBus card

Firmware/Driver Versions

AP f/w:
Wireless client driver:
Wireless client f/w:
No Info

Test DescriptionSNR (dB)Transfer Rate (Mbps)Response Time (msec)UDP stream
Throughput (kbps)Lost data (%)
Client to AP - Condition 1020.7
[No WEP]
[w/ WEP]
1 (avg)
2 (max)
Client to AP - Condition 20201 (avg)
2 (max)
Client to AP - Condition 3015.41 (avg)
4 (max)
Client to AP - Condition 4012.82 (avg)
3 (max)
See details of how we test.