Wireless Links For Computers

IN an office, most computers ``talk'' to one another over wires. Now, in a sign that radio signals may increasingly be used for short-distance transmission of computer data, Motorola Inc. has introduced a wireless system for personal-computer networks in the workplace. The move also shows that Motorola, the largest supplier of cellular telephone systems, is expanding in data communications, says Greg Cline of Information Strategies Group, a market research firm in Vienna, Va.

Motorola hopes potential buyers of its Altair system will deem the long-term savings more important than the up-front costs.

Interest in the new product is strong, according to Motorola representatives who came to Boston last week for NetWorld, an annual computer trade show for local-area networks, or LANs.

Computers in the workplace are typically moved every other year. The cost of rewiring a cable-based system averages several hundred dollars per machine, and can run as high as $1,000.

The Altair network, meanwhile, involves a $3,995 control module that processes radio signals from as many as six user-modules, which cost $3,495 apiece. Each user-module may have up to six computers linked to it by cable. The cost per user would be about $715 for a network with 30 computers linked to five user-modules, according to the Schaumburg, Ill., company.

``They're in a horse-race on pricing,'' says John Powers, a telecommunications consultant with TeleVenture Systems Consulting Group of Chelmsford, Mass.

Mr. Cline says wireless systems are attractive in situations that involve frequent moves, difficult wiring (such as in old buildings), or concerns with data security - an area, he says, where wireless networks can be more effective than cable.

Although the market for wireless systems is growing fast, ``the jury is still out'' on whether these will eventually take on more than a niche role in the overall market, says Frank Barbetta of Probe Research in Cedar Knolls, N.J.

Mr. Powers says networks are ``reaching the limits of transmission by copper wire,'' leaving the future to wireless systems or fiber-optic cables. Referring to the fast growth of cellular phones, he notes: ``If that whole [wireless] technology transfers inside the building, we've got an enormous market starting to evolve.''

Compared to other wireless systems, Altair gets high marks for performance and ease of use, Cline says. Altair can transmit data at 6.6 megabits per second, compared to 2 megabits for NCR Corporation's WaveLAN, another wireless system introduced in September.

Altair is designed to work with Ethernet, one of two main network operating systems. WaveLAN relies on its own system, rather than Ethernet or Token-Ring, and costs $1,390 per user. Analysts say Motorola is probably working to make Altair compatible with Token-Ring, the other main system.

Altair transmits at 18 gigahertz, a high frequency that Motorola licensed last April when it became available from the Federal Communications Commission (FCC). This frequency's low power, a drawback for long-distance transmission, is an advantage for LANs, allowing hundreds of thousands of users to coexist within a 35-mile licensed area without interference, Motorola says. The signal will penetrate most walls, but becomes weak outside a 150-foot diameter area.

WaveLAN operates at around 0.9 gigahertz. The FCC also allows computer networks to use 2.4 and 5.8 gigahertz frequencies, Cline says. In addition, Apple Computer Inc. last month asked the FCC to grant the computer industry frequency rights around 1.9 gigahertz.

Other available systems transmit at lower data rates, or use infrared technology, which requires a line-of-sight transmission path between the systems.

``The real question is who's ultimately going to be the distributor of this'' technology, Powers says. He foresees regional telephone companies entering the market and becoming dominant distributors. Motorola, meanwhile, is negotiating with Tech Data, ComputerLand, and MicroAge to sell Altair.