Baltimore County Public Schools Network Wirelessly

Baltimore County Public Schools (BCPS) has deployed a wireless LAN (WLAN) from Meru Networks to support video learning, Internet access and other applications for nearly 105,000 students as well as faculty and staff in 171 schools with more than 15 million square feet of total space.

The WLAN will enable one of the nation's largest school systems to take full advantage of increasingly popular video learning tools, such as Safari Montage, while giving users of those tools the option of mobility.

BCPS began its deployment last summer with a pilot wireless network in each school, and since then has installed approximately 2,000 wireless access points. Plans call for full wireless coverage in all schools by the start of the fall 2008 term. Selected areas of the BCPS system -- including some administration buildings and a newly-built elementary school -- have high-performance wireless access based on the new IEEE 802.11n standard, which offers access speeds up to five times faster than those of the earlier 802.11a/b/g standards.

Michael Goodhues, CIO for BCPS, said the need for pervasive wireless networking in the BCPS system was driven by the growing number of laptop computers in the schools and the increasing use of digital media-based instructional tools, along with the high costs associated with cabling and installation of wired networks.

"The Blueprint for Progress, our school system's foundational document, recognizes the strategic role of technology in the classroom and sets a goal of providing all our teachers and a growing proportion of students with their own computers," Goodhues said. "Increasingly, these computers are wireless-enabled laptops. With the WLAN, users can carry their laptops around school campuses and have the same access experience virtually anyplace. And as schools expand or shift resources between locations, we won't be facing massive rewiring costs."

In early 2007 Fusion Network Systems helped BCPS conduct a comprehensive evaluation of wireless solutions.

Bob Henley, Fusion's CEO, said, "Video is a key application for BCPS, but most of the wireless solutions we tested wouldn't allow more than three or four simultaneous users on the network without dropping connections. In the schools' extremely high-density user environment, that wasn't acceptable. With the new system, we had 30 desktop computers and 20 laptops in a single lab running video with just one access point. Meru's "airtime fairness" capability lets data, voice and video applications all get their fair share of bandwidth, so everyone contending for access gets a smooth, concurrent connection.

"Meru's Air Traffic Control technology also gave us switch-like performance with no co-channel interference, even when we installed additional APs to fill coverage gaps," Henley added. "And because with their single-channel approach there's no need for channel planning, it's easy for the BCPS technical staff to manage."

The investment in newer 802.11n access points for some BCPS locations isn't just about high-speed access, Henley explained. Because the 11n APs have high-speed interfaces, and the schools' wired network switches offer gigabit interfaces, there is a substantial increase in throughput that allows the WLAN to handle many more users at once. "This means we can get by with fewer access points, so it's cost-effective to install 11a/b/g/n equipment even if we don't initially activate the 11n radios," he said.

The access points used in the BCPS WLAN deployment are the AP150, with one 802.11a radio and one 802.11b/g radio; and the AP311, with one 802.11a/b/g/n radio and one 802.11a/b/g radio (software-upgradeable to 11n). Each building also has a Meru MC1015 controller, which supports up to 30 access points and provides the WLAN with centralized intelligent RF management, advanced quality of service and security.

The system's single-channel approach to wireless coverage minimizes co-channel interference by automatically selecting one channel for use enterprise-wide and layering additional channels when more capacity is required. With all access points occupying the same channel, the system creates a "virtual cell" that boosts the reliability of wireless connections independent of client type and minimizes dropped connections by eliminating the need for "handoffs" when mobile users move between access points. In contrast, most legacy WLANs use a "micro cell" approach, which assigns different channels to adjacent network cells, requiring careful and time-consuming channel selection and power-level planning and limiting future network expansion.