Wireless Community Networks
A Guide for Library Boards, Educators, and Community Leaders
Appendix A. Glossary
ADSL—Asynchronous Digital Subscriber Line; a new type of service run over regular voice-grade telephone lines; requires special end-user equipment, but provides from 400Kbps-1Mbps transfer speeds. Not yet available in most areas.
airwaves—radio waves used to transmit radio and television broadcasts across free space; also used to describe the connection medium between two wireless bridges.
ASCII—American Standard Code for Information Interchange; a code for microcomputers that assigns a numeric code from 0 to 255 to each of the letters of the English alphabet, numerals, punctuation marks, and many other language characters.
bandwidth—commonly used to indicate how much, or how fast, data can be transmitted across a telecommunications line or network connection in a period of time, usually one second; used synonymously with data transfer rate, throughput, and line speed.
binary—a system comprised of two unique components; the base-2 number system, representing all numeric values with just two digits, 0 and 1.
bit—binary digit; represents a binary value of zero or one; the smallest unit of storage on a computer; represented by the lowercase letter b.
bps, bits-per-second—a common unit of measure for data transfer rates.
byte—a unit of eight bits commonly used to encode textual data; now used to measure the storage requirements of various data objects; represented by the uppercase letter B.
Cat5, or Category 5, cable—the recommended level of unshielded twisted pair cable used in most new local area network installations.
channels—a specific band of the radio frequency spectrum used for radio transmissions.
communications medium—the electronic component used to connect two network devices to facilitate network data transmission; usually refers to some type of data cabling (coaxial, thinnet, or twisted pair) or telecommunications line; in RF wireless networking, refers to radio energy.
community network—in this manual refers to the equipment and telecommunications services making up a community-wide computer network or WAN; technically referred to as a municipal area network. In many other contexts, it is used to describe a computer service through which information about a community is collected and disseminated.
crosstalk—a type of interference in a cabled medium caused by emanations from a nearby cable.
data—any type of information transmitted across a computer network from one machine to another; includes such items as word processing files, database records (like patron records, student grades, or customer billing records), card catalog information, pictures, sounds, or even just keystrokes.
data circuit—a leased telecommunications line; also called a dedicated data circuit.
data transfer rate, or data rate—the number of bits that can be transferred across a network connection in one second; commonly used as a synonym for throughput or bandwidth; technically, it is always greater than throughput because extra bits are included in each data packet for routing purposes.
download—to copy a computer file from a server on a network to an individual user's computer.
driver—software included as part of a hardware kit, providing functions which allow an operating system to control the hardware device.
Ethernet—a standard computer networking communication format. It is the most common network format in use today. Token Ring is another that is still in wide use in businesses.
fiber optics—technology that uses the transmission of light along glass tubes (fibers) for data communications.
G, giga—an abbreviation for the value one billion; since computers use the binary number system instead of decimal, the actual value represented is 1,073,741,824.
gain—a measure of the amount of focus an antenna uses transmitting/receiving a radio signal.
hardware—the physical components of a computer or network.
hertz—a unit of measure of electromagnetic frequency named after Heinrich Hertz; one hertz corresponds to one cycle per second (or one wave per second).
interference—extraneous natural or man-made radio emissions that overpower or cancel a portion of a radio signal.
interlocal agreement—a legal document describing an agreement between two or more local governmental agencies to work as one agency on a project. The agreement generally lists the rights and responsibilities of each participant.
Internet backbone—the top-level, or primary, routers and telecommunications circuits interconnecting all of the major computer networks that make up the Internet.
Internet Service Provider (ISP)—a commercial or public agency providing interconnections to the Internet, either via network or dial-up services; services rendered vary greatly between public and commercial providers.
ISDN line—(Integrated Services Digital Line); a special phone line, carrying only digital (discrete) signals. ISDN lines are switchable and can be used as regular phone lines; they are primarily used to carry data traffic. Two types are available: BRI (basic rate interface) and PRI (primary rate interface), which is equivalent to 23 BRI lines.
ISM bands—three non-licensed radio frequency bands, originally intended for the Industrial, Scientific, and Medical communities; these are typically used for radio frequency wireless networks.
K, kilo—an abbreviation for the value one thousand; since computers use the binary number system instead of decimal, the actual value represented is 1,024.
LAN—local area network; a group of computers connected over a communications medium for the purpose of sharing access to centralized resources (files, printers, CD-ROM products).
latency—the very short delays created in the packaging, transmission, and acknowledgement of network data requests.
licensing—the process of regulating the use of radio and microwave frequencies by assigning rights to use specific frequency bands in a geographic area; the U.S. Federal Communications Commission (FCC) is the administrative agency responsible for licensing these frequencies.
line of sight, also radio line of sight—the visible, unobstructed path required to enable radio communications between two distinct access points.
M, mega—an abbreviation for the value one million; since computers use the binary number system instead of decimal, the actual value represented is 1,048,576.
MAN—municipal area network; a network of two or more interconnected local area networks, generally located inside a single community.
medium—see communications medium.
multi-point—a network connection that allows one centralized site to connect to multiple remote sites simultaneously.
narrowband transmissions—radio frequency transmissions that use a very thin slice of frequencies; the narrow bands are sometimes referred to as channels.
network operating system—software which provides control of the network functions of a computer and the local area network (LAN).
network protocol—a set of rules used for the process of packaging, starting, interrupting, and continuing network data communications.
network security—the implementation of procedures designed to limit access to resources to a predetermined set of staff and/or public computer users and prevent the tampering, unauthorized use, or destruction of computer data.
point-to-point—a network connection that is tied directly to two locations.
POTS—Plain Old Telephone Service; a regular voice-grade telephone line.
protocol—see network protocol.
radio energy—electromagnetic radiation in the radio frequency spectrum.
radio frequency spectrum—the portion of the electromagnetic spectrum from approximately 30kHz to 1GHz.
radio frequency communications—the use of radio energy to carry voice and data signals between two or more access points.
redundancy—the characteristic of having independent, alternative routes available for data communications in the event of failure of a primary connection.
repeater link or repeater station—a third site in a wireless network connection which has line of sight to the two primary access points; the repeater link uses a pair of wireless bridges and antennas to repeat signals to each of the remote sites.
right-of-way fees—fees incurred by crossing public or private land in the process of burying cable or pipeline or installing cable on utility poles. These usually take the form of monthly or annual payments to the rights holder.
site survey—the preliminary investigation of the sites involved in a wireless network installation; explores line of sight issues, sources of potential interference, transmission distances, and physical structures.
security—see network security.
software—a set of binary instructions that allows a user to control a computer or network device.
spectrum analysis—the process of analyzing a portion of the radio spectrum to determine if another agency may be using it for communications.
spectrum analyzer—a device that searches a band of radio frequencies for the presence of radio signals.
streaming video—full-motion video, such as that seen in movies or on TV, delivered across a computer network; the computer user sees the video playing onscreen as it is delivered, rather than after the complete file as been downloaded.
T-1 lines—a special type of telephone line called a data circuit. They connect two distinct points to allow intercommunication. They are not "dialable," or switchable. They can carry both voice and data signals.
telecommunications—the process of communicating over telephone wires, either by voice conversation or computer networking; also used to describe equipment used in the communication process, such as telephones or network devices.
telecommunications line—a "telephone" line leased from the local phone company; also known as a dedicated data circuit.
throughput—commonly used as a synonym to data transfer rate or bandwidth. In wireless applications it refers to the actual quantity of data that can be transmitted over a wireless link.
transponder—the portion of a satellite which transmits and receives radio signals in a prescribed frequency range, from ground stations or other satellites (transmitter/responder).
under-utilized line—a telecommunications line in which much of the potential throughput is unused.
WAN—wide area network; a network of two or more interconnected local area networks (LANs), generally located in two or more communities.
wideband transmissions—radio frequency transmissions that use a very large range of frequencies; see also narrowband transmissions.
wireless bridge—a combination device that includes a network bridge and a radio transceiver; the bridge connects a local area network (LAN) to the radio link.
wireless Ethernet—wireless network connections that provide a throughput of 5-7Mbps, which is similar to the data throughput of standard, wired Ethernet networks.
wireline connection—a network connection using traditional cabled media such as network cable and telecommunications lines; also called cabled connectivity.
Written by Robert L. Williams.