Dartmouth retools for Wi-Fi video

Dartmouth College has embraced Wi-Fi for data so enthusiastically that the school's IT chief is leaping into voice and video over Wi-Fi. A venture that calls for tripling the number of access points on campus, swapping out old wireless gear for smarter equipment and partnering with a start-up that is still putting the finishing touches on its technology.

With video set to go into production in April, the Hanover, N.H., school is beefing up its Wi-Fi network to support four channels of educational video, says Brad Noblet, director of technical services for the college. "We have a little over 600 access points today covering 150 buildings in a mile square. I'm going to come close to tripling that in order to increase the amount of bandwidth so I can deliver video and handle a number of concurrent VoIP telephone conversations."

The current Wi-Fi network, based on Cisco gear, is used primarily for e-mail, instant messaging and Web surfing, he says, but the school has greater needs.

"A lot of the faculty feel like to capture the attention of their students, they have to do more than just stand there and talk," he says. That means adding video presentations as part of the curriculum.

Ideally that would mean student laptop access to audio, video and data in classrooms, but that would require an Ethernet jack at each desk, a huge infrastructure upgrade. "We want to take four channels for teaching and learning and make those available on wireless as well as wired so we can again have this mobile classroom effect," Noblet says. "You don't need a smart classroom." The new wireless gear will support existing data applications and Internet access.

The school has teamed up with Video Furnace , a start-up that multicasts video to laptops using client software agents downloaded to PCs when users select the encrypted videostreams they want. The company supports Macintosh, Linux and Windows operating systems, all of which are used on campus. In addition to supporting the educational streams, Video Furnace also will deliver commercial cable TV to the campus over Dartmouth's converged wired IP network, Noblet says.

Because each computer needs 400K to 2M bit/sec of bandwidth to screen video content (depending on screen size and resolution), efficient use of bandwidth is key.

Bandwidth for 802.11a is provided at 55M bit/sec using its own radio frequency. 802.11b supports 11M bit/sec, and 802.11g supports 55M bit/sec, but 802.11b and 802.11g share the same frequency. If an 802.11b device associates with an access point, the access point drops down to 11M bit/sec for 802.11g users.

That led Noblet to choose 802.11a. "I'm going to be able to get on the order of 20 to 25 streams per access point," he says.