Introduction
| BuffaloTech AirStation 54Mbps Wireless USB Adapter (WLI-USB-G54 ) | |
|---|---|
| Summary | The first USB-based 802.11g wireless client adapter. Uses Broadcom ’54g’ technology. Requires USB 2.0 for max speed, but can be used with USB 1.1 too. |
| Pros | • Supports WPA • Accepts external antenna • No throughput loss due to USB |
| Cons | • Does not support Broadcom “Xpress” throughput enhancement • No integrated WPA supplicant in client application • Over 20% throughput loss in WPA TKIP mode |
Buffalo Tech’s WLI-USB-G54 AirStation 54Mbps Wireless USB Adapter is the first-announced and first-available 802.11g adapter that supports connection via USB 2.0. It’s also the only 11g / USB2 adapter announced so far to be based on Broadcom’s AirForce chipset. All the others from NETGEAR, Linksys and D-Link use GlobespanVirata’s (formerly Intersil) PRISM GT chipset.
The USB-G54 comes in the same, small, inverted-“L” package used by Buffalo’s WLI-TX1-G54 11g Ethernet converter and WLA-G54C 11g AP / Bridge / Repeater. It’s small enough to be inobtrusively tucked away or even left out in plain sight.
The main downsides to the package are that cable weight can drag it around, there aren’t screw-mounting features on the unit or its detachable base, and it has fixed position internal antennas. The pluses are that the antennas are dual diversity and that a higher-gain external antenna can be added via an MC type connector.
The USB-G54 is based on Broadcom’s BCM94333U reference design which is built around the BCM4333 802.11 Bridge Processor. The mini-PCI radio is marked as a Buffalo Tech WLI-MPCI-G54, but the FCC ID on the radio and on the USB-G54 says the radio is essentially a copy of Broadcom’s mini-PCI reference design.
There are two diversity antennas inside the case; one fastened vertically to the lower front panel, the other horizontally mounted along the top of the upper case. This top antenna unit contains the RF switch / MC connector for an external antenna, which is covered by a removable plastic plug.
Tip: During performance testing I found that you need to point either side of the USB-G54 in the direction of your AP for best results.
Setup and Admin
Admin is via WinXP’s ZeroConfiguration or the Client Manager program supplied by Buffalo if you’re running other OSes.
Figure 1: BuffaloTech Client Manager Profile Edit screen
Figure 1 shows the Client Manager edit screen for a wireless profile and you can see that there are a few things missing. You can’t set Transmit rate, adjust power save mode, or force the adapter to an 11b-only mode.
Broadcom’s mixed-mode throughput-enhancing “Xpress” technology isn’t supported either, nor can you take advantage of the Wi-Fi Protected Access (WPA) modes that Buffalo supports in its drivers. If you use WinXP with the WPA patch or a third-party supplicant, you’ll see that WPA and WPA-PSK are supported with both the mandatory TKIP and optional, stronger AES encryption.
Documentation needs work since there’s only a printed Quick Start Guide. There’s no User Manual either on the install CD or on BuffaloTech’s support website, but additional documentation (for Buffalo’s Notebook Adapter) can be obtained by clicking on the ? in the Client Manager.
Wireless Performance
Although I have a USB2-equipped desktop machine, the notebook that I normally use for client testing remains at USB 1.1. But not to be kept from my appointed throughput-testing rounds, I just connected a Belkin F5D7130 AP [reviewed here] to my notebook and left the USB-G54 lashed to my 2.4GHz Pentium4 desktop, sitting where the test AP normally is. Figure 2 shows the test results.
Figure 2: Four location throughput
(click on the image for a full-sized view)
I should note that you can’t directly compare these results – or any results going forward – with those of previous reviews before October 1, 2003. My recent move meant setting up new test locations, which are described here.
The new Location 3 test is the only one done from a point one floor below the stationary AP location. The poorer performance for Location 3 might be due to the unusual antenna design of the USB-G54, but it could just be the way the radio waves crumble in the new test location. Only time – and more product testing – will tell for sure.
I also ran tests in WEP128, WPA-PSK / TKIP, WPA-PSK / AES modes and found a significant throughput loss (24%) only in WPA-PSK / TKIP. All other modes had variation within the accuracy of my test methods. This is consistent with what I’ve found on other Broadcom-based products, and does put you at a throughput disadvantage if you mix the USB-G54 (or any other Broadcom-based client supporting WPA) with WPA-enabled APs or wireless routers based on GlobespanVirata (Intersil) or Atheros chipsets.
The best-case average throughput of about 20Mbps is consistent with Broadcom-based 11g products based on Ethernet or CardBus interfaces. So it appears that – unlike 802.11b USB1.1 adapters – you won’t pay a throughput penalty for connecting via USB 2.
You will lose throughput, though, if you use the adapter with a computer supporting USB 1.1, as Figure 3 shows.
Figure 3: Throughput connected to USB 1.1
(click on the image for a full-sized view)
Smooths things right out, doesn’t it? Although you wouldn’t buy the USB-G54 specifically to attach to a USB 1.1-equipped machine, it’s nice to know that you at least have the option.
802.11g Wireless Performance Test Results
| Test Conditions
– WEP encryption: DISABLED |
Firmware/Driver Versions
AP f/w: |
||||
|---|---|---|---|---|---|
| Test Description | SNR (dB) | Transfer Rate (Mbps) | Response Time (msec) | UDP stream | |
| Throughput (kbps) | Lost data (%) | ||||
| Client to AP – Condition 1 | 0 | 20.4 [No WEP] 19.9 [w/ WEP] |
1 (avg) 2 (max) |
499 | 0 |
| Client to AP – Condition 2 | 0 | 13.2 | 1 (avg) 3 (max) |
499 | 0 |
| Client to AP – Condition 3 | 0 | 2.8 | 3 (avg) 6 (max) |
347 | 29 |
| Client to AP – Condition 4 | 0 | 11.7 | 2 (avg) 3 (max) |
499 | 0 |
See details of how we test.
Wrap Up
11g / USB-2 adapters were a long time coming, but the dam now appears to have broken and product a’ plenty from BuffaloTech, NETGEAR, Linksys, D-Link and others is flooding into the market.
BuffaloTech’s WLI-USB-G54 performs pretty much like its notebook (CardBus) adapter, but also gives you the option of attaching an external antenna. Just as with 11b USB adapters, pricing is higher than its CardBus equivalent, but not as high as using a wireless Ethernet adapter.
If you’ve been waiting for these beasties to be available so that you could get your desktop onto your wireless LAN without having to pop open the case and wrestle a PCI-based board in, then go ahead and take the plunge. At a maximum transfer rate of 480Mbps, USB 2.0 has enough bandwidth headroom to not crimp 802.11g’s maximum 54Mbps raw data rate and have plenty left over for other devices connected to it. Pay your money, take your choice and set your desktop machines free!