The 802.11b/WiFi market is growing because it offers excellent value and multivendor interoperability. However, in an age of commoditized Gigabit Ethernet, it's tough to take a product that offers a paltry 11-Mbps data rate too seriously, especially when throughput is half that amount and bandwidth is shared. In addition, 802.11b systems are susceptible to interference from other unlicensed wireless devices, particularly 2.4-GHz cordless phones and Bluetooth devices. 802.11a systems run at 54 Mbps and, more important, offer eight nonoverlapping radio channels (compared with three for 802.11b), providing significantly more installation flexibility.

Proxim 802.11a (screen view) Click here to enlarge

Administrators want to see fast performance and reasonable range without the laptop battery running dry in less than 30 minutes. That's the challenge Proxim and other 11a early implementers face; if they can pull it off, they will alter the WLAN playing field.

In the Beginning

Although I am eager to test a full 11a solution, for now I focused on Proxim's Harmony 802.11a CardBus Card. The card is considerably more expensive than Agere's Orinoco 802.11b NIC, but if you agree that cost should be measured on the basis of dollar per Mbps, it's actually significantly cheaper.

With two NICs I was restricted to running my tests in peer-to-peer, ad hoc mode--not exactly a rigorous examination of the product's enterprise readiness. Nonetheless, this setup let me get a feel for range and performance. Installation went smoothly, and the quality of Proxim's configuration utilities impressed me.

The card supports all 802.11a speeds--54, 48, 36, 24, 18, 12, 9 and 6 Mbps--as well as a proprietary Proxim 2X mode, which runs at 108 Mbps. WEP (Wired Equivalent Privacy) also is supported (at 40, 128 and 152 bits).

I set up two 300-MHz Pentium III notebooks running Microsoft Windows 2000 and conducted throughput tests in our lab using NetIQ's Chariot 4.1 benchmarking software.

Running 100 iterations of 1-MB TCP-based unidirectional file transfers (filesendl), the test setup achieved a throughput of 21.7 Mbps when running at a data rate of 54 Mbps (.40 throughput-to-data-rate ratio). In comparison, a similar setup using Agere's Orinco 802.11b cards achieved a throughput of 5 Mbps (throughput-data-rate ratio of .45); and a setup with 3Com Fast Ethernet cards achieved 83 Mbps (throughput-data-rate ratio of .83). In Proxim's proprietary 2X mode, which uses two 11a channels, the test achieved a throughput of 31 Mbps (throughput-data-rate ratio of .29). I ran the same tests with 152-bit WEP enabled and saw no performance degradation.

For range testing, I set up the notebooks at both ends of a hallway approximately 160 feet long. Although the data rate periodically dropped below 54 Mbps (automatic fallback is a standard feature on 802.11 networks), throughput still measured about 14.5 Mbps. When I closed two glass and steel doors about halfway down the hallway, throughput fell to around 11 Mbps. Using the Orinoco 802.11b NICs in the same environment yielded throughput of 4.7 Mbps, regardless of whether the doors were open or closed.

When I tested in other locations in the building--around hallway corners and between walls--range fell off more noticeably at distances in excess of 100 feet, but I was impressed and, to be honest, somewhat surprised by the results.

Because of deadline constraints, I was not able to systematically assess battery life, which most experts expect to be less than that of 11b offerings. However, in my subjective assessment, I did not detect dramatic differences between 11a and 11b battery drain.

Infrastructure Mode

Some vendors are so insecure about their shipping products that they refuse to send those products to us for testing. Yet Proxim sent us a prebeta version of its Harmony 802.11a Access Point. I hoped that given the power and antenna limitations of PC Cards, I would see better range when running in 802.11 infrastructure mode using an access point.

Unfortunately, it didn't turn out that way. I had installation, range and performance problems using the prebeta access point, and after burning many hours trying to isolate the cause, our lab staff, Proxim and I decided to call a time-out.

This is no criticism of Proxim: The company warned me I'd be working with gear that hadn't been optimized for performance or range.

Although I wasn't able to adequately test the system's performance in infrastructure mode, I was able to gain a better feel for the unique Harmony architecture. Unlike most access points, which essentially are glorified 802.3 to 802.11b bridges, Proxim's product separates the access-point and bridging functions by tunneling all wireless traffic through a switched-Ethernet infrastructure to an access controller that also serves as a central management point for the Harmony system.

The access-point controller's Web interface provides a centralized management console, from which a network administrator can manage all wireless equipment--including both 802.11a and 802.11b access points--on his or her network. From a functionality standpoint, Harmony's primary appeal rests in its ability to support roaming across IP subnets, but the system also can expand in functionality to support enhanced security.

Vendor Information Harmony 802.11a CardBus Card, $249. Available: Now. Proxim, (800) 229-1630, (408) 731-2700; fax (408) 731-3675 www.proxim.com

Tunneling all wireless traffic through one or more access controllers, though a good idea, raises concerns about potential performance bottlenecks, especially when using high-speed 11a systems. In answer, Proxim supports a "managed mode," where access points gain more autonomy without sacrificing a central point of management. You give up the IP roaming capability, however, when operating in managed mode.

Proxim's Harmony architecture represents an effective way to accommodate both 11a and 11b clients. Products based on the 11a standard will need some time to mature, and I'd be reluctant to recommend a strategic commitment before silicon is available from multiple sources and multivendor interoperability can be demonstrated. But if you have applications that need high-speed wireless today, Harmony 802.11a is certainly worth a look.