Microsoft Office Tutorials and References
In Depth Information
Telecommunications
In a local area network LAN ), computers and peripheral devices are located (
tively close to each other, generally in the same building. A wide area network WAN ) (
is more than one LAN connected together. The Internet is the largest example of a WAN.
In a wireless local area network WLAN ), computers and peripherals use high-frequency (
radio waves instead of wires to communicate and connect in a network. Wi-Fi (short for
wireless fi delity ) is the term created by the nonprofi t Wi-Fi Alliance to describe networks
connected using a standard radio frequency established by the Institute of Electrical and
Electronics Engineers (IEEE). Wi-Fi is used over short distances to connect computers to a
LAN. Wi-Fi can be especially useful in buildings with older wiring.
A personal area network PAN ) is a network that allows two or more devices located (
close to each other to communicate or to connect a device to the Internet. In a PAN,
devices are connected with cables or wirelessly. Infrared technology uses infrared light
waves to beam data from one device to another. The devices must be compatible, and
they must be positioned close to each other with their infrared ports pointed at each
other to communicate. This is the technology used in TV remote controls. Bluetooth
uses short-range radio waves to connect a device wirelessly to another device or to the
Internet. The devices must each have a Bluetooth transmitter; unlike infrared
connections, they can communicate around corners or through walls.
WiMAX (short for Worldwide Interoperability for Microwave Access ), another
standard defi ned by the IEEE, allows computer users to connect over many miles to a LAN.
A WiMAX tower sends signals to a WiMAX receiver built or plugged into a computer.
WiMAX towers can communicate with each other or with a company that provides
connections to the Internet.
The computer advertised in the Visual Overview is not currently part of a network but
does include an integrated network interface card. With the appropriate network
software, this computer can be connected to a network.
Telecommunications
Telecommunications means communicating over a comparatively long distance using a
phone line or some other data conduit. To make this connection, you must use a modem.
Modem stands for mo dulatordem odulator. The modem converts the digital , or stop-start,
signals your computer outputs into analog , or continuous wave, signals (sound waves)
that can traverse ordinary phone lines.
Most computers today come with a built-in 56K modem and a NIC (network
interface card). The number 56 represents the modem’s capability to send and receive about
56,000 bits per second bps ). People who want to use a high-speed connection either (
over phone lines, such as a DSL digital subscriber line ), or over a cable connection, (
usually need to purchase a separate external DSL or cable modem. High-speed
connections are often called broadband connections .
A high-speed connection will enable Elizabeth and Scott to connect to suppliers at
other locations without waiting an undue amount of time to send and receive data.
The Internet
The Internet is the largest network in the world, connecting millions of people. It has
become an invaluable communications channel for individuals, businesses, and
governments worldwide.
Most people fi rst experience the Internet by using electronic mail, more commonly
called email. Email is the capability to send a message from one user’s computer to
another user’s computer where it is stored until the recipient opens it. The vast network
of networks that make up the Internet pass the message along through electronic links
called gateways . Elizabeth and Scott would benefi t from the advantages of email: speed
and ease of communication with vendors and customers, lower postage costs, lower
long-distance charges, and increased productivity.
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