Information Technology Reference
In-Depth Information
SUMMARY
Principle
A telecommunications system and network have
many fundamental components.
communications in one of three frequency ranges: radio,
microwave, or infrared.
Wireless communications solutions for very short
distances include near field communications, Bluetooth,
ultra wideband, infrared transmission, and Zigbee. Wi-Fi
is a popular wireless communications solution for medium
range distances. Wireless communications solutions for
long distances include satellite and terrestrial microwave
transmission, wireless mesh, 3G, 4G, and WiMAX.
Reallocating frequency in the 700 MHz spectrum might
lead to new and more effective wireless solutions as well as
a national voice and data network for public safety agencies.
The geographic area covered by a network determines
whether it is called a personal area network (PAN), local area
network (LAN), metropolitan area network (MAN), or wide
area network (WAN).
The electronic flow of data across international and global
boundaries is often called transborder data flow.
When an organization needs to use two or more computer
systems, it can follow one of three basic data-processing
strategies: centralized (all processing at a single location,
high degree of control), decentralized (multiple processors
that do not communicate with one another), or distributed
(multiple processors that communicate with each other).
Distributed processing minimizes the consequences of a
catastrophic event at one location while ensuring uninter-
rupted systems availability.
A client/server system is a network that connects a user's
computer (a client) to one or more host computers (servers).
A client is often a PC that requests services from the server,
shares processing tasks with the server, and displays the
results.
Numerous telecommunications devices commonly
employed include modem, multiplexer, front-end processor,
PBX, switches, bridges, routers, and gateways.
Telecommunications software performs important func-
tions, such as error checking and message formatting. A
network operating system controls the computer systems
and devices on a network, allowing them to communicate with
one another. Network-management software enables a
manager to monitor the use of individual computers and
shared hardware, scan for viruses, and ensure compliance
with software licenses.
The interception of confidential information by unautho-
rized parties is a major concern for organizations. Encryption
of data and the use of virtual private networks are two com-
mon solutions to this problem. Special measures must be
taken to secure wireless networks.
The wide range of telecommunications and network appli-
cations includes cellular phone services, digital subscriber
line (DSL), VoIP, linking personal computer to mainframes,
voice mail, reverse 911 service, voice-to-text services, home
Telecommunications and networks are creating profound
changes in business because they remove the barriers of time
and distance.
The effective use of networks can turn a company into
an agile, powerful, and creative organization, giving it a
long-term competitive advantage. Networks let users share
hardware, programs, and databases across the organization.
They can transmit and receive information to improve
organizational effectiveness and efficiency. They enable
geographically separated workgroups to share documents
and opinions, which fosters teamwork, innovative ideas, and
new business strategies.
In a telecommunications system, the sending unit
transmits a signal to a telecommunications device, which
performs a number of functions such as converting the signal
into a different form or from one type to another. The telecom-
munications device then sends the signal through a medium
that carries the electronic signal. The signal is received by
another telecommunications device that is connected to the
receiving computer.
Communications can be classified as synchronous or
asynchronous.
A transmission medium can be divided into one or more
communications channels, each capable of carrying a mes-
sage. Telecommunications channels can be classified
as simplex, half-duplex, or full-duplex.
Telecommunications protocols define the set of rules
that governs the exchange of information over a telecommu-
nications channel to ensure fast, efficient, error-free
communications and to enable hardware, software, and
equipment manufacturers and service providers to build
products that interoperate effectively. There is a myriad of
telecommunications protocols, including international,
national, and regional standards.
Channel bandwidth refers to the rate at which data is
exchanged, usually expressed in bits per second.
Principle
Telecommunications, networks, and their associated
applications are essential to organizational success.
The telecommunications media that physically connect
data communications devices can be divided into two broad
categories: guided transmission media and wireless media.
Guided transmission media include twisted-pair wire cable,
coaxial cable, fiber-optic cable, and broadband over power
lines. Wireless transmission involves the broadcast of
