Oct 31 2006

10 Tips for a High-Reliability Wireless Network

Here's some security and troubleshooting advice for cutting the cord.

As notebook PCs become as big a presence in the classroom as the traditional textbook, the need for students to be connected to the Internet and the school’s intranet continues to grow in importance, as does the ability to disconnect from the wired network and use notebooks in a variety of locations.

“My teachers are asking me when they can disconnect the network cable and use their notebook PC outside the traditional classroom,” says Mark Barhorst, technology specialist, Fort Loramie Schools in Fort Loramie, Ohio.


Schools across the country are dealing with the same need for anywhere, anytime connectivity. Here are 10 tips to help school districts deploy the kind of high-reliability wireless network that will keep students in touch with one another, their teachers and all the knowledge the Internet has to offer.



A site survey enables a school to map out access points, locate dead zones and prevent overlapping APs. There are various ways to conduct a site survey, such as by touring the campus with an access point and a couple of clients to check signal strength.

Alternatively, an in-house site survey can be conducted with a handful of wireless network interface cards (NICs). “With some research and time, you can do your own site survey and save your district some money,” says Tom Jess, director of technology for Graham Local Schools, St. Paris, Ohio. Start by placing the access point in a suitable location. Using the tools that came with the wireless card, walk the building to check for signal strength.


As with most computer hardware, it is generally a good idea to make sure the latest firmware, patches and drivers are loaded on every device. In addition, the newest version of software may include features not available in prior versions.

Ohio Hi-Point Career Center, located in Bellefontaine, Ohio, uses Hewlett-Packard ProCurve 420 APs. After upgrading to version 2.10, multiple SSID (service set identifier, the unique name of the wireless network) capability was enabled on the access points, and new security features were added. Wireless network cards should also be upgraded. For example, the Intel PRO/Wireless 2200BG wireless LAN cards used at Ohio Hi-Point kept dropping connections to the HP ProCurves, but the problem cleared up once the Intel drivers were updated.


One brand of wireless card may work better on a particular network than another, so try products from different vendors. Ohio Hi-Point solved part of the dropped-connection problem by using a different brand of wireless card.


Utilize multiple channels when deploying APs because this technique reduces the amount of interference APs have with one other. Each wireless channel operates within a range of frequencies.

The only three channels that do not overlap on 802.11b/g are 1, 6 and 11. Some technicians suggest using channels 1, 4, 7 and 11 because that provides more operating channels. However, with a four-channel installation, channels 1 and 4 overlap, 4 and 7 overlap, and 7 and 11 overlap.


The choice of encryption standard will depend on the type of data that will be sent over the wireless network. Wired Equivalent Privacy encryption is generally not considered very secure. But if users will only be surfing the Web, WEP should be considered — or no encryption at all.

However, if e-mail, student grades or other sensitive information is being sent, something stronger is needed. Wi-Fi Protected Access encryption is much stronger, but most 802.11b equipment doesn’t support WPA encryption.


Many common devices operate on the same radio frequencies as wireless networks. For example, most microwave ovens operate at 2450MHz, which is used by wireless channels 7 through 10. Many cordless phones operate in the 2.4 gigahertz spectrum. Some companies use the 802.11a band because fewer devices use that radio spectrum. This will most likely change over the next few years as more and more devices become wireless.

To help detect interference, use a wireless spectrum analyzer, which might help solve other problems as well. At Ohio Hi-Point, for instance, use of a wireless spectrum analyzer located an AP that was not transmitting on a continuous basis.


Some APs will support Power over Ethernet (PoE), which is useful when deploying the APs. Typically an AP is mounted high on the wall or in the ceiling. But PoE eliminates the need to run a power outlet to the AP and doesn’t limit a school to installing the AP near a power outlet.

Either a network switch with built-in PoE capability or a PoE injector is required. A multiport injector looks like a network switch, but the ports may be labeled “data in” and “data and power out.” The real benefit to PoE comes when a nonresponding AP needs rebooting. Given the choice between climbing a ladder to access the AP or rebooting a PoE injector, most would opt for the injector any day.


Decide how the SSIDs should be configured. With a single SSID for all wireless APs (WAPs), users can more easily roam around campus. Location-specific SSIDs, on the other hand, force users to establish a connection to their new WAPs if they go mobile.


Standardizing with one network hardware manufacturer will save time and money, says Fort Loramie’s Barhorst. Only one company will have to be contacted when things go wrong (and they eventually will). In addition, technicians will have only one interface to get used to and one product to support.


It can be difficult to keep up with all the changes in this constantly shifting field. Don’t pretend to know everything. Ask vendors for help when problems arise.


About 54 percent of EdTech readers said they implemented or expanded their school’s wireless network during the past summer.


Below are the major wireless standards from the Institute of Electrical and Electronics Engineers, a nonprofit technical professional association based in New York City:

802.11a: Up to 54 megabits per second (Mbps), operates in 5 gigahertz (GHz) spectrum; not compatible with 802.11b spectrum. 802.11a has a relatively short range. It uses 12 nonoverlapping channels, 8 dedicated to indoor and 4 to point to point.

802.11b: Up to 11Mbps, operates in 2.4GHz spectrum. The b band requires fewer access points to cover the same amount of area. 802.11b operates over 14 different channels, 11 of which are approved by the Federal Communications Commission (FCC) for use in the United States.

802.11g: Up to 54Mbps, operates in 2.4GHz spectrum. The g band is backward-compatible with 802.11b equipment. It operates over 14 different channels, 11 of which are approved by the FCC for use in the United States.

802.3af: Power over Ethernet requires running only one CAT5 wire to the access point, with power delivered over Ethernet cable rather than a traditional 110-volt outlet.

John Case is technology coordinator for the Ohio Hi-Point Career Center in Bellefontaine, Ohio. His Web site is www.schooltechtools.com.