As schools adopt wireless technology in lieu of running miles of cable through their buildings, the issue of bandwidth becomes even more critical.
Today’s wireless access points support data transmission speeds of up to 11 megabits per second, but as the number of students using a given access point increases, transmission speeds can slow considerably. The typical solution is for schools to add more access points, but this also adds cost.
A Chicago-based company called Wireless Information Networks says it has developed a unique solution to the problem. The company’s engineering staff has developed and patented a series of network designs that company officials say actually enhances bandwidth allocation by as much as 30 percent over more traditional wireless solutions.
In a typical wireless radio frequency (RF) deployment, a transceiver broadcasts a signal as far as it can go until the signal dissipates and bandwidth is lost.
“We believe that’s the wrong way to do wireless,” said Tom Crotty, founder and president of Wireless Information Networks. Through RF engineering, Crotty said his company has come up with a way to control the propagation of signals so the network can accommodate more users in a given area.
One of the company’s setups, called a dual-density antenna system, consists of a transceiver and two antennas, each placed about 50 feet from the transceiver. Another, called a quad-density antenna system, has four antennas spoking off a single transceiver.
The antennas extend the effective range of the wireless signals, enabling each user’s device to “see” a greater number of bridges or transceivers. Simply put, this gives users access to more bandwidth at any given time, without having to install additional access points.
Most of today’s network interface cards come with built-in “dynamic bandwidth allocation.” This means that as the amount of available bandwidth from a given transceiver becomes saturated, the next device that tries to access the network will look for another bridge or transceiver. If it can’t see another access point, it will link to the one it does see and slow the network further. Therefore, the more portals a device can see, the better.
“We demand in our design that each laptop be able to see a minimum of threeand preferably sixnetwork portals,” Crotty said.
Because the company’s patented technology enables it to control the propagation of signals, users don’t experience what Crotty calls “channel conflict,” which happens when signals collide and cancel each other out.
“If you have more than three transceivers or portals in a defined area that can see each other and you add a fourth, you typically experience channel conflict, and it brings the network to its knees,” he said. “Because we can control where the signal is going, we don’t experience channel conflict. As a result, we can deliver more bandwidth in a high-density area than any other vendor.”
Crotty wouldn’t say how the company is able to control the propagation of signals, except that it has to do with the polarization of antennas. “It took us many months to develop this solution,” he said. “We don’t want to divulge our secret.”
Besides extending bandwidth, the company’s solution also delivers greater flexibilitywhat Crotty calls “full roaming” capabilities.
At any given time, he explained, a school might have pockets of students concentrated in a certain area of the building. In this scenario, some might be connected to a transceiver they are directly under, while others might be connected to transceivers on the other half of the building through the company’s use of the extended-range antennas.
Thus, no matter how many students are concentrated in a given area, network performance doesn’t have to suffer.
Schools in Chicago, Sacramento, and Kansas City, Kan., are among those that have implemented the company’s wireless solution.
The company’s network design “has freed us up to use computers when the teachers want and how they want, based on the lessons they plan,” said Brent Johnson, principal at Sacramento’s Natomas Park Elementary School (K-5, enr. 600). “I think it is a tremendous resource, just in terms of versatility and being able to spread the resources where we need them.”
Natomas Park’s two buildings have been wireless-ready since January, Johnson said. Each building has 12 classrooms and three wireless access points, plus a motorized cart equipped with 32 Hewlett-Packard laptops. The total cost: about $75,000.
Wireless Information Networks’ MobiLAN ONE laptop cart was one of the first such products on the market. Each “computer lab on wheels” is a self-contained unit that includes its own access point and houses up to 32 laptops that students can use throughout the day. To make operations easier, the cart has a motor that propels it down the hall at three miles per hour.
At the end of the school day, teachers simply wheel the unit to wherever it is to be housed for the night, plug it into an electrical outlet, and charge the batteries on the laptops and the motor for the next day. Because the cart operates on batteries during school hourswhen electricity use is highestit doesn’t require educators to tap their already strained electrical resources.
The company’s unique network architecture means Natomas Park has more flexibility than schools that merely purchase one of the many movable laptop carts now marketed to schools, Johnson said.
“From what I’ve seen of other wireless programs, they are linked to the cart,” he said. “Placing access points in the building allows us the freedom to use any number of computers in the exact place we want to put them. With just the carts, you could set up lab, but there is not the same flexibility.”
Installation of the wireless network is far quicker than cable-based installations, Johnson said.
“We had our district put electrical and data connections at different points throughout the buildings,” he said. “It only took about a day and a half to install all the access points.”
So far, the response from students, teachers, and parents has been overwhelmingly positive.
“We also have a pretty strong training program to teach teachers how to use basic programs, like Microsoft Word [and] PowerPoint,” Johnson said, adding that Natomas Park chose to provide staff development through Intel’s Teach to the Future program.
“We’re very excited about how it will impact the learning of the kids,” he said.
Wireless Information Networks
Natomas Park Elementary School