TECH TALK

Dear Tech Talk—

We desperately need another electronic classroom, but our library doesn’t have any extra rooms or unused space that can be dedicated to another classroom, especially one filled with large, cumbersome computers and wires. Please — can you suggest a solution for our problem?

—Desperately Seeking Instruction Space

Dear Desperately—

A possible solution that comes to mind for those of you with this problem and an adventuresome spirit — consider using laptop computers in a wireless electronic classroom. Although still in the realm of the “frontier”, wireless technology has undergone some major changes in the past twelve months. Major issues from a year ago are now dissipating.

To begin with, what is a wireless network? A wireless network IS NOT a network completely devoid of wires, but at the local level, individual computers connect to the main network without using a physical wire. Instead the PCs use a signal to connect to a nearby physical device (an access point). The access point IS physically connected to the main network with wires.

Briefly, there are three methods that can be used to implement a wireless network: Frequency Hopping Spread Spectrum (FHSS), Direct Sequence Spread Spectrum (DSSS), and infrared. With FHSS, “short bursts of data hop from one frequency to another based on a predetermined pattern, and the transmitter and receiver must synchronize this hop sequence” in order to transfer data. Whereas DSSS “is a high-bandwidth” technology that spreads signals over a wide range”, using a “redundant bit pattern”. There are advantages and disadvantages to each of these methods, and both are supported by wireless vendors. More detailed information about these two methods can be found in Ruber’s article. The infrared solution is less popular, most likely because its success requires that the transmitted signal be beamed in a straight line to the receiving device. For example, in order for someone to transfer data from one Palm Pilot to another (using infrared technology), both Palm Pilots must be in the same room and in relative alignment with each other. Both the DSSS and FHSS methods use radio frequencies and are less hindered by spatial positioning and physical obstacles such as walls and floors.

Computers, in this case laptop computers, capable of receiving a wireless signal need to be at the receiving end. Computers with wireless capabilities can be obtained by purchasing a wireless card (for about $200) for each laptop or by purchasing laptops with wireless capability already built into the unit. (Although not all laptops come with built-in wireless capability, it’s a desired feature because it eliminates the potential of damage to the wireless card.) The laptop is then configured to connect to the wireless network. Additionally, if library patrons have their own laptops with wireless capabilities, they can be given the information to configure their laptops to communicate with the library’s wireless network.

There are some definite advantages to having a wireless network available in a library:

• Wireless networks can sometimes circumvent the cost of installing a wired network, especially in areas of a building where thick concrete, asbestos, architectural features, historical preservation, or other similar obstacles exist.
• Because there are no wires to run, except from the access point devices to the wired network, installation can take place very quickly.
• Rooms in the library that aren’t tied to wired usage become more flexible.
• The laptops are available for patron checkout or other uses when not needed for classes.

• Although the speed of wireless networks continues to increase (having gone from 2 Mbps to 11 Mbps within the last 18 months), it will always lag behind the speed of most wired networks.
• There are bandwidth issues associated with having several computers accessing the wireless network at the same time. Instructing the users of 20 laptops to connect to a networked resource (such as a web-based database) at the same time may not be a trivial matter within a wireless network. Response under these conditions needs to be tested and addressed.
• Wireless networks aren’t as secure as wired networks.
• When moving around in a wireless network, signals may deteriorate and data or the connection may be lost (although this would be less of a problem in a classroom setting).
• Installation of a wireless network may not be the least expensive way to provide network access to an area. The cost effectiveness will depend on the physical barriers that need to be addressed if a wired network is installed.

LIRT News, March 2001. Volume 23, number 3.
To report problems, please contact the LIRT News Production editor at jronan@ufl.edu

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