Review: TRENDnet TEW-664UB

By Lisa Phifer

April 21, 2009

This dual-band 802.11n-draft 2 USB adapter brings 5GHz to home WLANs.

Review: TRENDnet TEW-664UB

TRENDnet TEW-664UB      

Price:  $62.99

Pros:  Dual-band flexibility; competitive price; WMM and WPS

Cons:  Limited EAP types; not yet Wi-Fi-certified

TrendNet TEW-664UB.jpg

802.11n is not yet ratified, but already we're seeing fourth-generation products hit the market. Residential WLANs started with pre-N offerings, replaced by buggy draft 1 and then more reliable draft 2 products, operating in the 2.4 GHz band. But when Wi-Fi Alliance certification triggered enterprise adoption last year, users began to experience 802.11n in a whole new way.

Specifically, business WLANs designed for high-density usage and demanding multimedia applications are now being deployed in the 5 GHz band, with WMM prioritization. But when those workers head home, they usually return to unruly competition in the 2.4 GHz "junk band."

Given the coming wave of sexy multimedia products that will require reliable voice and video distribution throughout the home, 5 GHz and WMM may soon be needed in residential WLANs as well. The TRENDnet TEW-664UB, a dual-band 802.11n USB adapter, attempts to satisfy this burgeoning consumer demand at a competitive price.

Suiting up

The dual-band TEW-664UB ($62.99) is TRENDnet's successor to the single-band TEW-644UB ($40.99). Like the old 644UB, the new 664UB is USB 2.0 wireless adapter that can be used by Windows 2000/XP/Vista (32/64bit) and MacOS X 10.4/10.5 clients. Both adapters support 802.11n data rates up to 300 Mbps, using two internal antennas. (One antenna is visible in above photo of adapter that has been removed from its black plastic enclosure). The old 644UB is Wi-Fi Draft N certified; we hope to see the new 664UB achieve that essential milestone soon.

The biggest difference between these adapters is the 664UB's ability to operate in both the 2.4 and 5 GHz bands. For compatibility with the vast majority of existing WLANs, the 664UB can still associate with 802.11b/g/n APs. But to facilitate more demanding multimedia WLANs, the 664UB can also connect to 802.11an APs over one of nine 5 GHz channels in the US (four in Europe).

During tests, we found the 664UB to be compatible with both 20 and 40 Mhz wide channel operation in both the 2.4 and 5 GHz bands. In fact, 802.11n APs must be configured to use 40 GHz channels, two spatial streams, and a Short Guard Interval (400ns) for the adapter to reach its maximum supported data rate of 300 Mbps.

The 664UB's new dual-band radio is probably responsible for its increased thirst. According to specs, the new 664UB draws up to 300mA in receive mode, 450mA in transmit mode (compared to 250mA / 320mA for the older 644UB). The 664UB's 802.11b/g/n transmit output power remains largely unchanged at 16, 13, and 13 dBm respectively, dropping to 10 dBm for 802.11a.

On the receive side, the 664UB has become slightly less sensitive when talking to older 802.11b/g APs, but is now a better 802.11n listener. According to specs, the older 644UB could only receive at rates up to 150 Mbps with -63dBm sensitivity. But the new 664UB handles receive rates up to 300 Mbps with -66dBm sensitivity. In theory, the 664UB should now hear signals that are half as strong, thus maintaining high rates at greater distances. But in practice, our range was not as impressive as that sounds (see Working Out).

We note that TRENDnet also sells a "high power" sibling to the older 644UB: the TEW-645UB ($49.99). The 645UB sits in an upright 3dBi antenna enclosure that TRENDnet says doubles that single-band adapter's 802.11n range. It would be interesting to see how well the dual-band 664UB might fare if repackaged with high-gain antennas.

Warming up

The 664UB adapter is supplied with a pictorial Quick Install Guide, CD, and USB cable. The CD contains a fairly basic 24-page User Guide, Win32 drivers, and a Win32 client utility. (MacOS users will need to download a driver from TRENDnet's support site.) Users new to 5 GHz or WMM won't find any insight here—TRENDnet apparently assumes that anything users need to know about these technologies should be supplied by AP documentation. (For example, see TRENDnet's TEW-672GR Dual Band Wireless N Gigabit Router.)

We installed the 664UB on a couple of Windows XP and Vista PCs without incident, using the client utility setup wizard and also doing a manual install without TRENDnet's client. We conducted most tests with TRENDnet's client utility (Figure 1), but had to use Windows Wireless Zero Config for some security tests. The adapter worked flawlessly with both clients, with one exception: Windows refused to disable the adapter when using TRENDnet's client.

Fig1-Survey_sm.jpg

Figure 1. Click to enlarge. 

Most users will start by using the client's Site Survey panel to locate available wireless networks—note that TRENDnet's client identifies individual APs and their channels (not just SSIDs like WZC). Attempting to connect to any AP launches the client's Configuration panel (Figure 2), where users can enter any security parameters required by that WLAN.

Fig2-Config.jpg

Figure 2.

Like most USB adapters intended for residential use, the 664UB supports WEP, WPA-Personal (TKIP/PSK), and WPA2-Personal (AES/PSK) security. In addition, the 664UB supports WPA/WPA2-Enterprise with client certificate 802.1X authentication (EAP-TLS). As shown in Figure 2, TRENDnet's client cannot be configured to use other 802.1X extended authentication protocols—notably client password-based PEAP. However, we were still able to connect the 664UB to an AP that required PEAP by using Windows WZC to manage the adapter. This is an odd client limitation, since home owners are far more likely to secure their WLAN with passwords than with certificates (that is, if they use 802.1X at all...)

In fact, most home owners that are new to WLANs will probably take advantage of the 664UB's Wi-Fi Protected Setup (WPS) feature (Figure 3). WPS is a Wi-Fi Alliance certified method of automating secure WLAN configuration by producing randomly-generated SSIDs and WPA2-PSKs. A home owner that purchases a WPS-capable AP and adapter either pushes a button on the AP itself or enters a client-supplied PIN into the AP's security configuration. This causes the adapter and AP to perform a secure handshake, exchanging the PSK that the client will need to authenticate to the WLAN in the future. With WPS, users don't have to think up strong PSK values or type them into configuration screens. This is a desirable feature in residential products, and we were happy to see it supported by the 664UB's client utility.

Fig3-WPS.jpg

Figure 3.

Once associated, the 664UB's status can be viewed through the client's Link Info panel (Figure 4). Transmit and receive activity graphs are a nice touch but really more helpful for debugging network issues (like DHCP failure) than for tracking network or application performance.

Fig4-Status.jpg

Figure 4.

Oddly, this client does not offer a "Disconnect" button, so when WLAN association problems occurred there was nothing we could do but use Site Survey to rescan for available networks or remove and reinsert the USB adapter. While this client stores Profiles to reconnect to WLANs in the future, it does not provide prioritization or automated reconnection to specified profiles.

Finally, the 664UB supports WMM prioritization, but this feature is not enabled/disabled or otherwise visible through TRENDnet's client utility. However, users can enable/disable WMM itself and automatic power save delivery (APSD) for individual WMM access classes by configuring the adapter's driver properties (e.g., AC_BE support APSD). (Most users just rely on AP settings to make use of WMM where appropriate.)

Working out

In general, 802.11n products can achieve better range, reliability, and throughput by using multiple input multiple output (MIMO) antennas to exploit multipath. These variables are related to one another and to the unique RF propagation characteristics of each venue. For example, although data rate (and therefore throughput) declines with distance, throughput experienced in one location 50 feet from the AP can be higher than the range experienced at another location 30 feet from the AP due to the way in which nearby walls and doors reflect transmissions.

Nonetheless, we decided to measure our 664UB's range to see if we'd come close to the 50 meter indoor range advertised by TRENDnet. We ran iPerf UDP throughput tests, using the 664UB to transmit numerous 30 second traffic samples, measured at 10 foot increments from the AP. (We were reviewing an Aerohive 340 3x3 MIMO AP at the same time, so used it to support these informal open-air tests.)

As shown in Figure 5 below, our ability to sustain useful communication with the 664UB stopped around 150 feet when using 802.11n at 2.4 GHz and 120 feet at 5 GHz. All tests were performed with a 40 MHz wide channel and no SGI, resulting in a max possible data rate of 270 Mbps—as expected, UDP throughput topped out at roughly half that number. In other words, we experienced very nearly the advertised range at 2.4 GHz—but UDP throughput dropped below 40 Mbps well short of that distance. Note that our 664UB's throughput dropped off even more steeply at 5 GHz—a factor to be considered when deciding which band to use and where.

Fig5-UDP.jpg

Figure 5.

Bear in mind that the above measurements were not taken in a controlled lab environment. Although we chose channels with no known interferers, we did not make any attempt to maximize throughput by selecting locations with rich multipath. Users should expect their own experiences to differ to some degree.

To provide another basis for comparison, we ran another set of tests, using IxChariot to measure TCP upstream and downstream throughput for several different 802.11abgn clients at four random locations. As shown in Figures 6 and 7, the 664UB [blue bars] very clearly outpaced our representative 802.11g (2.4 GHz) and 802.11a (5 GHz) clients [yellow bars].

Fig6-TCP24.jpg

Figure 6.

However, the 664UB frequently underperformed the Intel WiFi Link 5300: an enterprise-class dual-band PCIe adapter with three antennas [green bars]. Results were more mixed versus the Cisco Linksys WPC600n: a residential-class dual-band PCMCIA adapter with three antennas [purple bars]. The 664UB fared better when compared to a single-band Belkin N Wireless ExpressCard [orange bars]. Again, these are just a few samples; your own mileage will vary.  But they suggest that an entry-level USB wireless adapter with only two antennas cannot be expected to yield quite as much "802.11n" benefit as the pricier adapters we might use at work.

Fig7-TCP5.jpg

Figure 7.

Conclusion

Home users shopping for an 802.11n USB adapter should consider the TRENDnet TEW-664UB—once it passes Wi-Fi Alliance certification. Sure, there are other dual-band 802.11n USB adapters on the shelves at BestBuy or Fry's like the Linksys WUSB600N ($80), Netgear WNDA3100 ($79), and D-Link DWA160 ($89). But the 664UB delivers similar features at a ~20% discount. Furthermore, anyone planning to distribute multimedia over their home WLAN tomorrow should really start prepping for 5 GHz today. A dual-band, WMM-capable adapter like the TEW-664UB can help home owners make this transition without spending big bucks.

Lisa Phifer owns Core Competence, a consulting firm focused on business use of emerging network and security technologies. She has been involved in the design, implementation, assessment, and testing of NetSec products and services for over 25 years. For more by Lisa Phifer, read "Retailers Need to Shore Up Defenses."



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