Editor of this issue:

William Self, The Medical Library Center of New York, 5 East 102nd St., 7th Floor, New York, NY 10029 S-1, Phone: 212-427-1630, Fax: 212-860-3496, E-mail: wself@mlcny.org.

A wireless network functions just like a regular, "wired" network, but information is transmitted through the air using radio frequencies rather than through cables. In order to make a network connection, a computer needs a NIC (network interface card), or a USB (Universal Serial Bus) network adapter. Wired NICs have RJ-45 ports that are connected to network cables. Wireless NICs have transceivers with built-in antennae instead. Wireless NICs are available for devices such as personal computers, laptops, and PDAs (personal digital assistants).

A computer configured with a wireless NIC communicates with a network through an AP (access point). APs have transceivers with antennae, which let them communicate with wireless devices or other APs. They also connect by cable to a network. Several wireless devices can connect to a single AP at a time, but the more devices that are using the AP, the slower the connection will be. Wireless devices are not very expensive. APs cost from about $150 to $500. Wireless NICs cost around $100. Wireless networks usually use DHCP (Dynamic Host Configuration Protocol). This means that a computer with a wireless NIC does not have to be assigned a specific IP address.

There are several standards for configuration of wireless local area networks in use right now. The IEEE 802.11 group, Bluetooth, and HomeRF are commonly used. IEEE 802.11 is becoming the most popular standard. Starbucks is implementing it in some of their coffee shops. 802.11 is a standard developed by the Institute of Electrical and Electronics Engineers. The earliest version of this standard is 802.11b, which is also known as Wi-Fi. 802.11b operates on the 2.4-gigahertz band of the radio frequency spectrum and can transfer data at speeds up to 11 megabits per second over a distance of 100 feet from access point to wireless device. A newer version of the standard is 802.11a. 802.11a operates on the 5-gigahertz band and can transfer data at speeds up to 54 megabits per second. 802.11b has a range of about 60 feet. Since these two standards operate at different frequencies, they are not compatible; an 802.11b NIC will not work with an 802.11a access point. A new standard, 802.11g, which will be available soon, promises to be compatible with 802.11b and transfer data at speeds of up to 54 megabits per second.

There are many uses for wireless networks in libraries.

• Patrons could bring their own laptops into the library to do their research.
• Some libraries require patrons to purchase their own wireless NICs. Other libraries lend wireless NICs or laptops.
• A wireless network would allow Internet access in places that cannot easily be wired. This would be particularly useful in older buildings, or buildings with open spaces.
• Library staff could take advantage of the mobility granted by a wireless network with projects such as inventory control, or remote circulation.
• Bibliographic instruction could "go mobile". Classes could be taught in any area within the range of an AP.

An important consideration when implementing a wireless network is the placement of APs within the library. Speed and performance degrade the farther the wireless device is from an access point. Architecture and furniture are important considerations, because structures like elevator shafts, supporting columns, and metal shelving are very good at blocking signals. Testing must be done to determine the best placement of APs for the widest range of access (like in the cell phone commercial where the man is walking the globe, asking "Can you hear me now?"). Performance will slow down when many devices are trying to connect to an AP at one time.

Users of the IEEE 802.11b standard should keep in mind that other devices such as cellular phones and microwave ovens also use the 2.4GHz radio frequency band. This means interference could degrade network performance and cause it to become unreliable.

Security is still an issue for wireless networks. Because they depend on radio waves, they are vulnerable to outside eavesdropping. Wireless networks do have some built-in security features. IEEE developed a protocol called WEP (Wired Equivalent Privacy), which was supposed to make wireless networks as safe as wired ones. Although this protocol has been found to have many flaws, it is a good first step. Its features include several levels of encryption and network access codes.

Other types of wireless connectivity exist. IrDA (Infrared Data Association) is used by PDAs and laptops, but it has limited usefulness. It is slow, requires line-of-sight contact for the devices communicating with each other, and has a range of about one meter. WAP (Wireless Application Protocols) is used to provide access to information services and application using the screens of cellular phones.

Traditional, wired networks run at speeds from 10 megabits per second to 100 megabits per second. They are still faster and more secure than wireless networks. Although wireless will not render obsolete wired networks any time soon, they definitely can extend a library's networking capabilities.

Additional Resources:

Wireless Hardware (a sample of what's out there, not a recommendation):

• Linksys: http://www.linksys.com
• Netgear: http://www.netgear.com
• SMC: http://www.smc.com
• U.S Robotics: http://www.usr.com

Libraries using Wireless technology:

• Wireless Networking Access in the VCU Libraries. 2002; Virginia Commonwealth University Libraries, http://library.vcu.edu/wireless/
• Wireless access in the library. 2002; UTHSCSA Library Web Team. http://www.library.uthscsa.edu/faq.cfm#WirelessLAN1

Further Reading:

Breeding M. The benefits of wireless technologies. Information Today 2002;19(3):42-3.

Ginzburg B. Goin' mobile: Using a wireless network in the library. Computers in Libraries 2002;21(3):40-4.

Glover J. Look ma, no wires! Or, the 10 steps of wireless networking. Computers in Libraries 2001;21(3):28-32.

A walk on the wireless side. Bulletin of the American Society for Information Science and Technology 2002;27(5), http://asis.org/Bulletin/Jun-01/cushing.html

Wireless Computing. Smart Computing in Plain English Learning Series 2002;8(5).

Libwireless Discussion Group, http://people.morrisville.edu/~drewwe/wireless/libwireless.html