The U.S. Military Academy at West Point is deploying an 802.11a, 54M bit/sec wireless LAN as part of a new strategy to create a much more interactive classroom, where cadets are not simply passive listeners to an information broadcast by a teacher, but active participants. A high-speed wireless LAN is one element in creating this interactivity.

Traditionally, a professor would explain why it was so important for Col. Joshua Chamberlain to hold the Union Army's left flank at Little Round Top during the Civil War Battle of Gettysburg. But with the wireless classroom and a variety of specialized applications on laptops and servers, cadets can run a computerized simulation to see the consequences of failing to hold that critical hill.

Wireless LANs are making it cost-effective for the academy to give each student this capability, says Col. Donald Welch, the academy's associate dean for information and education technology. "It would be a lot more expensive, and much less flexible, to make every classroom 'information rich' by wiring desktop computers [instead of using wireless LANs]," he says.

In the fall of 2002, the academy deployed a large-scale pilot network of 105 802.11a access points from SMC Networks, covering classrooms in the biggest academic building. Based on that experience, the IT group deployed the wireless net in two other buildings and is working now on the fourth. By August, when the Class of 2007 enters, there will be 369 802.11a access points, one in every classroom and lab. Every cadet will have a wireless laptop.

There were two interrelated reasons for choosing 802.11a, Welch says - higher bandwidth and throughput, and eight nonoverlapping channels for clients, compared with three channels for 802.11b. When channels overlap, the interference causes throughput to plummet. To create 802.11b wireless "cells" with nonoverlapping channels on multiple floors in a building, we have to spread out the access points, Welch says. That means more users per access point, vying for a throughput of, typically, about 5M to 6M bit/sec.

"With 802.11a, we can put an access point in every classroom, and there's no more than 19 people sharing that higher bandwidth [throughput of roughly 17M to 21M bit/sec]," Welch says.