Wireless Today . . .

Johns Hopkins University is working on its second full-scale wireless LAN upgrade.

The freedom promised by wireless networks - computing wherever you roam - is so compelling that the technology has remained a hot topic, even though few organizations are actually using it. In 1997, Johns Hopkins University's School of Public Health (SPH) became one of those few.


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What began as a wireless LAN pilot with 40 students has grown to 500 students today, fueled by the SPH's cash rebate program for students who buy laptops and another program for lending wireless LAN PC Cards.
"Of 600 new students [who will enroll this fall], half will either buy laptops or bring them with them," says Ross A. McKenzie, the SPH's information systems director. "By the time they leave, 80% will have them."
So, this summer, the school will upgrade its wireless LAN to the faster 802.11b Direct Sequence Spread Spectrum (DSSS) standard that was released last year, McKenzie says.
In 1995, the Baltimore-based university was facing "a forklift upgrade of all its wiring at a cost of about $2.5 million," says J. P. Garvin, the SPH's assistant IS director.
"Professors wanted to bring computing into the classrooms, which weren't then wired," he says.
"The school's dean also wanted to encourage students to get laptops," says McKenzie. "He feels they're important analytical and collaborative tools for public health officials.
"About 30% of our students are from foreign countries," McKenzie continues. "When they leave here, they go home to become the ministers of health for their region or country. They need the laptops for data-analysis tools and statistical-analysis tools."
The Costs of Wires
But upgrading the school's Ethernet LAN was going to be expensive, he says. Wiring the university's 80-year-old buildings would have required putting in a false floor at a cost of $10,000 per classroom. Including wiring costs, a conventional LAN would have cost $18,000 per classroom, McKenzie says. Wiring areas such as the cafeteria, with its huge expanse of windows, would have been impossible, Garvin adds.
The idea for the school's first wireless LAN was serendipitous, McKenzie says. On a visit to Texas Instruments Inc. in Dallas to evaluate laptops, he noticed lights on TI's staff laptops. "It was wireless LAN cards," he says.
By spring of 1997, the SPH had a pilot with 40 of its students. Information technology staff installed wireless LAN cards in the laptops and at access points in strategic sites at the SPH.
After a month, the pilot was being hailed as a success, but as a test, 20 students stressed the system by simultaneously downloading a 10MB file from an external Web site. All were able to download the file within five minutes.
A wireless LAN requires two access points per classroom, each of which includes a radio transceiver, 10Base-T port and encryption software. The access points connect to a hub on the Ethernet LAN.
The cost would be $3,000 per classroom - $15,000 less than for a conventional LAN, McKenzie says.
"When cabling is already deployed, DSSS [wireless] still costs about three times more," says Stan Schatt, an analyst at Giga Information Group Inc. in Dallas. But for such "green-field type implementations, the [Wireless LAN Association in Willoughby, Ohio] claims the payback is less than a year."
Where historic building status or asbestos in walls precludes drilling to wire for a conventional LAN, wireless is virtually mandatory, says Patrick Dryden, an analyst at Illuminata Inc. in Nashua, N.H.
Plus, Dryden adds, "the freedom to move desktops easily is a dream for users, business groups, building managers and IT managers."
The SPH concurred, says Garvin, "So we developed a three-year implementation plan."
"But our dean was so enamored of the idea, he told us to do it in six months," McKenzie says. "It was a little scary - there was no standard yet."
Over the next six months, the SPH installed nearly 100 access points throughout the campus and upgraded to IEEE 802.11 when the hardware became available in 1998.
The 802.11 standard includes Frequency Hopping Spread Spectrum (FHSS) signaling. Data travels on blocks that hop from one frequency to another every tenth of a second in a pseudorandom pattern known only to the sender and receiver.
DSSS signaling uses a broadband carrier and generates a bit pattern, or chip, for each bit of data. Each bit of data is identified, so the receiver can easily pick the data out of background noise.
Throughput speed for the new LAN will be greater. The FHSS data rate is 2M bit/sec., while DSSS signals transmit at a theoretical 11M bit/sec., although distance and physical blockages affect the rate.
Wireless has delivered on its promise at the SPH, Garvin says.
Chip Richter, a student in the SPH's distance learning program, agrees. "I see people using it all over campus to collaborate on projects and do research or use some of the analysis software" that the SPH loads on student laptops. "It's not just for e-mail and Internet access and taking notes," he adds.

Copyright © 2000 IDG Communications, Inc.

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