In a study recently commissioned by the Wireless LAN Alliance (www.wlana.com), a vendor-funded consortium, wireless LANs were found to have a pay-back period of 9.8 months on average (among the 34 organizations included in the study, conducted by Tech Research). Where mobility is an important component of the business process, wireless LANs can be highly beneficial. However, wireless LANs offer limited mobility at best, with a maximum communication range measured in hundreds of feet. If true mobility is required, you'll need to look at alternative wireless communication technologies like the CDPD (Cellular Digital Packet Data) standard, which operates at speeds that make modems seem fast.

Despite its limitations, wireless LAN technology can be tough to beat in the right applications, and, simply put, it's getting better all the time. If you're thinking about installing a wireless LAN, you'll need to learn a new set of buzzwords. Instead of the relatively simple technical issues associated with twisted-pair and fiber-optic media, you'll be faced with the nuances of radio-based communication. Thankfully, vendors have made significant strides toward easing installation. For example, most offer software tools that help network managers determine the optimum location of radio transceivers within a building.

Performance and Economics After more than seven years of deliberation, the IEEE endorsed a wireless standard in 1997. The end result is a mixed bag. On one hand, it provides a fairly robust standard at the MAC (Media Access Control) layer, but instead of one standard for the PHY (physical) layer, it offers three: FHSS (Frequency-Hopping Spread-Spectrum), DSSS (Direct-Sequence Spread-Spectrum) and infrared. While this freedom of choice is admirable, it causes confusion, bolstering the arguments of vendors challenging the status of 802.11 as the dominant standard driving the widespread adoption of wireless LANs.

This is where economics plays a big role in the wireless-LAN standards process. Yes, the 802.11 standard is good. It challenges vendors to build robust products. But, the research and development effort required to build a commercially viable product has prohibited mass-market economies of scale. The result: extraordinarily expensive products that cost up to 10 times as much as Ethernet. And what does that extra expense buy you? Only about 20 percent of Ethernet's performance.

Wireless LAN vendors are prepared to counter such criticism with reasonable arguments. Most will point out that the products are intended to supplement, rather than replace, a wired LAN infrastructure and the value-added proposition is very high when mobility is required. Regarding performance, vendors argue that 2 Mbps is fast enough for most terminal-to-host and well-written client/server applications--provided the network is engineered to avoid severe contention. For the most part, the vendors are right, but it's still a tough sell. The wireless LAN market may not be exploding, but it is growing. And potential for mass implementation still exists, provided costs can be driven down.

Spectrum, Radios and Modulation Choosing a portion of the electromagnetic spectrum in which a wireless LAN operates requires attention to both the technical issues surrounding radio-frequency transmission and the governmental policies that regulate spectrum usage. Most major vendors have settled on the 2.4-GHz frequency band allocated in the United States, Europe, Japan and elsewhere for unlicensed radio operation at low-power output. The 900-MHz products that were popular a few years ago are still viable where that portion of the electromagnetic spectrum is allocated for unlicensed operation, but they are no longer actively developed or promoted. The IEEE and many vendors are also evaluating technologies that allow for the release of products operating in the 5-GHz frequency band--also available for unlicensed operation in many jurisdictions, including the United States. However, a number of technical issues must be overcome before 5-GHz products with desirable form factors can be delivered. RadioLAN offers a series of products operating at 5 GHz that use low-power narrow-band transmission and provide 10-Mbps transmission speeds at a very reasonable price. But transmission distance is limited to roughly 100 feet, and the antennae are bigger than those of more conventional products.