Justin Watermann (left) and Dustin Hills of Raytown Quality Schools deployed 802.11n to boost bandwidth and improve wireless coverage.

Aug 20 2009

Clearing the Air: How Schools Are Outrunning Wi-Fi Interference

Schools look to 802.11n to manage increasingly crowded Wi-Fi space.

The city of Raytown, MO., is almost completely surrounded by Kansas City, and its schools' old 802.11b/g network was feeling the pressure of the encroaching population. Interference in the densely settled area is an important issue for the school system's wireless network, says Justin Watermann, technology coordinator at Raytown Quality Schools. 

The city of Raytown, MO., is almost completely surrounded by Kansas City, and its schools' old 802.11b/g network was feeling the pressure of the encroaching population. Interference in the densely settled area is an important issue for the school system's wireless network, says Justin Watermann, technology coordinator at Raytown Quality Schools.

In particular, parabolic radio antennas on a Kansas City Power and Light building across the street from the Raytown Schools Education and Conference Center interfered with the center's notebooks so severely that some teachers' computers were routinely knocked off the school's network, he says. Home wireless networks also caused sporadic interference at some of the districts 10 elementary, three middle and two high schools, says Dustin Hills, a network specialist for the district.

As a solution, Raytown turned to 802.11n Wi-Fi transmission gear, which offers more flexibility and higher data transmission capabilities than older 802.11b/g technology. The district installed 175 Aruba Network 802.11n access points among 22 sites, providing better control over network facilities, transmission and security. It plans to add another 50 APs, says Hills.

Raytown is not alone in its upgrade decision. Once considered an extravagance found only in high-end retail shops and airport frequent-flier lounges, Wi-Fi networks are now commonplace, even in education. Today, K–12 students across the country use the technology to access homework assignments, share information or surf the Internet from their desks, labs and even athletic fields.

Kids are growing up with the technology. We owe it to them,” Watermann says.

802.11n operates in 5 gigahertz and 2.4 megahertz spectrum bands, while b and g operate in 2.4GHz.

But that's good and bad, according to industry analysts and K–12 IT administrators. Although Wi-Fi can provide immediate Internet access, as well as the mobile convenience of wireless communication, it brings its own set of difficulties. Interference, evolving technology, retrofitting existing networks, ensuring compatibility with notebooks and making sure teachers know how to use the network top the list of issues that managers face.

Stable and secure

A key application for Wi-Fi networks is anytime, anywhere learning,” says Kelly Davis-Felner, marketing manager for the Wi-Fi Alliance, a nonprofit industry association that tests and certifies Wi-Fi equipment.

Although 802.11n hasn't been officially approved by the Institute of Electrical and Electronics Engineers, 802.11n equipment is widely available, Davis-Felner says. Networks that use the protocol can be particularly effective in schools. “It penetrates obstructions like cinder-block walls and is a bit more stable than b or g,” she says. “It is also a fatter pipe, allowing more data throughput.”

Because students are increasingly equipped with wireless devices, schools are a natural environment for Wi-Fi, says telecommunications analyst Jeff Kagan. “Along with that connectivity come the same problems that business networks often have,” he says. “That doesn't mean schools should shy away from it, however.”

Raytown didn't shy away. It upgraded its year-old 802.11b/g network with 802.11n technology, which gave it better coverage, more robust transmission and higher data rates for the 1,500 student and administration notebooks that use it.

Air Superiority

802.11n goes farther with more capacity

Wireless Standard 802.11b 802.11g 802.11n (draft)
Maximum Signaling Rate 11Mbps 54Mbps 300Mbps
Typical Range 300 feet 300 feet 450 feet
Standard Approved Yes Yes (late 2009)

Source: Burton Group


The new network can automatically scan for transmission blind spots in the network, import building floor plans showing AP locations and pump up power levels to overcome interference, Hills says. “The system also accommodates older b/g equipment,” he adds, which allowed the district to include old APs in the network.

The new network also provides better security. “We can pinpoint where users' stations are,” Hills says. “We actually found a rogue unregistered remote controller in a classroom ceiling.” The device created a potential opening into the wireless network that had been hidden until then.

Spring Branch Independent School District in Houston also found that 802.11n could extend more bandwidth to its buildings to support the growing use of multimedia by teachers, students and administrators.

Two years ago, Spring Branch decided to install a centrally managed, districtwide Wi-Fi network to cover its 51 buildings, including 46 elementary, intermediate and high schools. The district installed about 2,000 Aruba APs to support the network.

One of the biggest issues in the installation was updating network drivers, says CIO Venu Rao. Because the network was so big and covered such a wide area – more than 44 square miles – it encompassed a lot of ground, as well as existing equipment. “It took us a while to figure out how to do it,” Rao says.

Student Benefits

Farmington Municipal Schools in New Mexico also opted to replace its old 802.11b/g network with new 802.11a/b/g/n APs to support the 2,275 notebooks in its one-to-one student computer program, says Charles Thacker, the district's chief technology officer.

The school system implemented the one-to-one program for sixth-, seventh- and eighth-grade students and installed 75 802.11n APs in four middle schools to support the computers. It plans to install another 75 in its high school buildings when a one-to-one notebook program begins there this fall, Thacker says.

Farmington had an existing b/g network, but it had “issues,” Thacker says. Older clients on the network degraded performance for newer, faster clients, which wasn't a problem with only a few administrators on the network. With the addition of a thousand notebooks, “we knew performance would become an issue,” he says. But the Meru Networks 802.11n APs allowed end-to-end connectivity at b, g and n rates consistently.


Not Just for Students

Teachers and administrators at San Marino Unified School District near Los Angeles were the reason Stephen Choi, director of technology, installed a meshed Motorola 802.11n network. The network, connecting the district high school's seven buildings, was built primarily to support teachers' web-based resource planning applications, but can also serve as an interface between teachers, students, administrators and staff, Choi says.

“All our teachers have laptops,” Choi notes. The wireless network has given them the flexibility that the portable computers promised. Before the wireless network, teachers were tethered to their desktops, and cable had to be restrung if a teacher decided to move a computer across the room, he says.

That didn't make sense to Choi. With burgeoning multimedia programs and communications mobility rapidly becoming the norm in students' and teachers' lives, high bandwidth pipes had to be available in more places around campus, he decided.

The 802.11n Wi-Fi system, with mesh access points that link the district's buildings, can provide a high bandwidth highway almost anywhere, he says.



Farther, Faster, Stronger

  • 802.11n offers many reasons to upgrade, including:
  • Better coverage
  • Backward compatibility with older b/g networks
  • More data throughput
  • Minimized interference
  • Centrally managed access points
<p>Dan Videtich</p>