The Office Goes Wireless

Until recently, wireless LANs were considered a specialized technology used mainly in warehouses and logistics management. That began changing with the introduction of the 11M bit/sec. 802.11b and 54M bit/sec. 802.11a wireless Ethernet standards. Now the technology may be catching on for general office use. While just 8% of corporations have deployed WLANs, 54% say they plan to do so within two years, according to The Yankee Group in Boston. "Most enterprises recognize that wireless or mobility is a cornerstone of their future operations," says Yankee analyst Adam Zawel.

Currently, however, WLANs are still largely confined to specialized applications in hospitals, retail establishments, universities and warehouses. Within office buildings, WLAN deployments tend to be more limited. While the technology is mature enough for enterprisewide use, in many organizations it isn't considered essential to operations. Pittsburgh-based H.J. Heinz Co., for example, placed 20 Cisco Aironet 350 access points (AP) in its headquarters but installs APs elsewhere only when an office requests it. Heinz has no plans to provide enterprisewide WLAN access.

"There was no real business issue that WLAN addresses," says Kurt Kleinschmidt, a senior network analyst at Heinz. "It was just nice to have."

Organizations that do opt for a WLAN, however, face many critical decisions. First they must decide whether to use 802.11b or the newer, faster 802.11a technology. The answer depends both on bandwidth needs and the current level of WLAN deployment within the organization.

"Our recommendation, if you are installing it in a multistory corporate environment, is to look at 11a because of its scalability," says Mark Van Pelt, vice president of technical operations at WLAN consulting firm Donovan Consulting Group Inc. in East Brunswick, N.J. The 802.11a specification "has smaller cells but higher performance and less interference," he explains.

Cell size, or range, is just one factor in laying out a WLAN. AP radio frequency signals must pass through ceilings, floors, walls and other objects, and that results in signal degradation that the design must take into account.

Coverage can vary greatly from site to site, users say. The only real way to determine placement is by doing a site survey using the antennas to be installed, since different models produce different wave propagation patterns. And the survey must determine how a building's construction materials block or absorb signals.

"A lot has to do with the physical construction of the building, such as the amount of metal in the walls," says Jim Keeler, vice president of engineering development at Wayport Inc. in Everett, Wash., a company that sets up 802.11b networks in hotels and airports. "Airports contain absorbers of the 2.4 GHz band -- human beings -- so signal-coverage tests when empty are different than when crowded."

Too Much of a Good Thing

But having too many APs can be as bad as having too few. "If two APs are in the same room, both with the same signal strength, the client gets a bit nuts constantly evaluating whether it should be on this AP or that one," explains Van Pelt. "If the second one is far enough away that there is a [20-decibel] difference, there is no question."

Another important implementation consideration is the right security architecture to prevent unauthorized access.

Once an organization determines where APs go, they are relatively easy to install and configure. Windows 2000 and XP, and many handheld devices, are designed to automatically locate 802.11b signals. Wireless users can be managed using the same network/systems management software as hard-wired users.

"Configuring the access points is not much harder than just plugging them in," says Dr. John Halamka, CIO for the CareGroup Health System hospital consortium in Boston. "Placement and security are the difficult parts."

Robb is a freelance writer in Tujunga, Calif. Contact him at drewrobb@attbi.com

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