1. Telecommunications and Networks
LEARNING OBJECTIVES
Identify and describe the fundamental components of a telecommunications system.
■ Identify two broad categories of telecommunications
media and their associated
characteristics.
■ Identify several telecommunications hardware
devices and discuss their functions.
■ Telecommunications, networks, and
their associated applications are essential
to organizational success.
■ Describe the benefits associated with the use
of a network.
■ Name three distributed processing alternatives
and discuss their basic features.
■ List and describe several telecommunications
applications that organizations benefit from
today.
Princple
A telecommunications system and
network have many fundamental
components.
Telecommunications, networks, and
their associated applications are essential
to organizational success
Why Learn About Why Learn About Telecommunications and

2. Networks?Telecommunications and Networks?
Effective communication is essential to the success of every major human undertaking,
from building great cities to waging war to running a modern organization.
Today we use electronic messaging and networking to shrink the world and enable
people everywhere to communicate and interact effectively without requiring facetoface meetings. Regardless of your chosen major or future career field, you will
need the communications capabilities provided by telecommunications and networks,
especially if your work involves the supply chain. Among all business functions,
supply chain management might use telecommunications and networks the
most because it requires cooperation and communications among workers in
inbound logistics, warehouse and storage, production, finished product storage, outbound
logistics, and most important, with customers, suppliers, and shippers. All
members of the supply chain must work together effectively to increase the value
perceived by the customer, so partners must communicate well. Other employees in
human resources, finance, research and development, marketing, and sales positions
must also use communications technology to communicate with people inside and
outside the organization. To be a successful member of any organization, you must
be able to take advantage of the capabilities that these technologies offer you. This
chapter begins by discussing the importance of effective communications.
Elements of a
Telecommunications System
Telecommunications devices relay
signals between computer systems
and transmission media.
Sending computer
system and
equipment (1)
Telecommunications
Medium (4)
Receiving computer

3. system and
equipment (6)
Telecommunications
device (5)
Signal (2)
device (3)
AN OVERVIEW OF TELECOMMUNICATIONS
telecommunications medium
Any material substance that carries
an electronic signal and serves as
an interface between a sending
device and a receiving device.
telecommunications protocol
A set of rules that governs the
exchange of information over a communications
medium.
synchronous communications
A form of communications where
the receiver gets the message
instantaneously, when it is sent.
asynchronous communications
A form of communications where
the receiver gets the message after
some delay—sometimes hours or

4. days after the message is sent.
Basic Telecommunications Channel Characteristics
simplex channel
A communications channel that can
transmit data in only one direction.
half-duplex channel
A communications channel that can
transmit data in either direction, but
not simultaneously.
full-duplex channel
A communications channel that
permits data transmission in both
directions at the same time, so a
full-duplex channel is like two simplex
channels
channel bandwidth
The rate at which data is exchanged
over a telecommunications channel,
usually measured in bits per second
(bps).
broadband communications
A telecommunications system in
which a very high rate of data
exchange is possible.

5. Telecommunications Media
Guided Transmission Media Types
Media Type Description Advantages Disadvantages
Twisted-pair wire Twisted pairs of copper wire,
shielded or unshielded
Used for telephone
service; widely available
Transmission speed
and distance limitations
Coaxial cable
Inner conductor wire
surrounded by insulation
Cleaner and faster data
transmission than
twisted-pair wire
More expensive than
twisted-pair wire
Fiber-optic cable
Many extremely thin strands
of glass bound together in
a sheathing; uses light
beams to transmit signals
Diameter of cable is much
smaller than coaxial;
less distortion of signal;
capable of high
transmission rates

6. Expensive to purchase
and install
Broadband over
power lines
Data is transmitted
over standard highvoltage
power lines
Can provide Internet
service to rural areas
where cable and
phone service may
be nonexistent
Can be expensive and may
interfere with ham radios
and police and fire
communications
Wireless Communications Options
Technology Description Advantages Disadvantages
Radio frequency
Range
Operates in the 3KHz–300
MHz range
Supports mobile users;
costs are dropping
Signal highly susceptible to
Interception
Microwave—
terrestrial and
satellite frequency
range
High-frequency radio signal
(300 MHz–300 GHz) sent
through atmosphere and
Avoids cost and effort
to lay cable or wires;
capable of high-speed
transmission
Must have unobstructed line
of sight between sender and
receiver; transmission effective
only for short distances

7. Infrared frequency
range
Signals in the 300 GHz–400
THz frequency range sent
through air as light waves
Lets you move, remove,
and install devices
without expensive wiring
Must have unobstructed line
of sight between sender and
receiver; transmission effective
only for short distances
Short Range Wireless Options
Near Field Communication
(NFC)
A very short-range wireless connectivity
technology designed for cell
phones and credit cards.
..
Bluetooth
A wireless communications specification
that describes how cell
phones, computers, faxes, personal
digital assistants, printers, and
other electronic devices can be
interconnected over distances of
10–30 feet at a rate of about 2 Mbps.
ultra wideband (UWB)
A wireless communications technology
that transmits large
amounts of digital data over short
distances of up to 30 feet using a
wide spectrum of frequency bands
and very low power.
infrared transmission
A wireless communications technology
that operates at a frequency
of 300 GHz and above that requires
line-of-sight transmission and
operates over short distances—
such as a few yards.
Zigbee
Zigbee is a form of wireless communications frequently used in security systems and heating
and cooling control systems. Zigbee is a relatively low-cost technology and requires little
power, which allows longer life with smaller batteries.

8. Medium Range Wireless Options
Wi-Fi is a wireless telecommunications technology brand owned by the Wi-Fi Alliance,
which consists of about 300 technology companies including AT&T, Dell, Microsoft, Nokia,
and Qualcomm. The alliance exists to improve the interoperability of wireless local area
network products based on the IEEE 802.11 series of telecommunications standards.
With a Wi-Fi wireless network, the user’s computer, smartphone, or personal digital
assistant has a wireless adapter that translates data into a radio signal and transmits it using
an antenna. A wireless access point, which consists of a transmitter with an antenna, receives
the signal and decodes it.
When receiving data, the wireless access point takes the
information from the Internet, translates it into a radio signal, and sends it to the device’s
wireless adapter. These devices typically come with built-in wireless transmitters and software
to enable them to alert the user to the existence of a Wi-Fi network. The area covered by one
or more interconnected wireless access points is called a ―hot spot.‖ Current Wi-Fi access
points have a maximum range of about 300 feet outdoors and 100 feet within a dry-walled
building. Wi-Fi has proven so popular that hot spots are popping up in places such as airports,
coffee shops, college campuses, libraries, and restaurants.
Wide Area Wireless Network Options
Many solutions provide wide area network options including satellite and terrestrial
microwave transmission, wireless mesh, 3G, 4G, and WiMAX.
Microwave Transmission
Microwave is a high-frequency (300 MHz–300 GHz) signal sent through the air (see Figure
6.4). Terrestrial (Earth-bound) microwaves are transmitted by line-of-sight devices, so that
the line of sight between the transmitter and receiver must be unobstructed. Typically,
microwave stations are placed in a series—one station receives a signal, amplifies it, and
retransmits it to the next microwave transmission tower. Such stations can be located roughly
30 miles apart before the curvature of the Earth makes it impossible for the towers to ―see
one another.‖ Microwave signals can carry thousands of channels at the same time.
Microwave Communications
Because they are line-of-sight
transmission devices, microwave
dishes are frequently placed in
relatively high locations, such as
atop mountains, towers, or tall
buildings.
A communications satellite also operates in the microwave frequency range (see Figure
6.5). The satellite receives the signal from the Earth station, amplifies the relatively weak
signal, and then rebroadcasts it at a different frequency. The advantage of satellite communications
is that it can receive and broadcast over large geographic regions. Such problems
as the curvature of the Earth, mountains, and other structures that block the line-ofsight
microwave transmission make satellites an attractive alternative. Geostationary, low
earth orbit, and small mobile satellite stations are the most common forms of satellite
communications
Satellite Transmission
Communications satellites are relay
stations that receive signals from
one Earth station and rebroadcast
them to another.

9. A geostationary satellite orbits the Earth directly over the equator, approximately 22,300
miles above the Earth so that it appears stationary. The U.S. National Weather Service relies
on the Geostationary Operational Environmental Satellite program for weather imagery and
quantitative data to support weather forecasting, severe storm tracking, and meteorological
research.
A low earth orbit (LEO) satellite system employs many satellites, each in an orbit at an
altitude of less than 1,000 miles. The satellites are spaced so that, from any point on the Earth
at any time, at least one satellite is on a line of sight.
A very small aperture terminal (VSAT) is a satellite ground station with a dish antenna
smaller than 3 meters in diameter. News organizations employ VSAT dishes that run on
battery power to quickly establish communications and transmit news stories from remote
locations. Many people are also investing in VSAT technology in their homes to receive TV
and send and receive computer communications.
wireless mesh
A way to route communications
between network nodes (computers
or other devices) by allowing for
continuous connections and reconfiguration
around blocked paths by
―hopping‖ from node to node until a
connection can be established.
3G Wireless Communications
The International Telecommunications Union (ITU) established a single standard for cellular
networks in 1999. The goal was to standardize future digital wireless communications
and allow global roaming with a single handset. Called IMT-2000, now referred to as 3G,
this standard provides for faster transmission speeds in the range of 2–4 Mbps. Originally,
3G was supposed to be a single, unified, worldwide standard, but the 3G standards effort
split into several different standards. One standard is the Universal Mobile Telephone System
(UMTS), which is the preferred solution for European countries that use Global System for
Mobile (GSM) communications. GSM is the de facto wireless telephone standard in Europe
with more than 120 million users worldwide in 120 countries. Another 3G-based standard
is Code-Division Multiple Access (CDMA), which is used in Australia, Canada, China, India,
Israel, Mexico, South Korea, the United States, and Venezuela. The wide variety of 3G
cellular communications protocols can support many business applications. The challenge
is to enable these protocols to intercommunicate and support fast, reliable, global wireless
communications.
3G wireless communication is useful for business travelers, people on the go, and people
who need to get or stay connected. Although Wi-Fi is an option, 3G is preferable to mobile
users concerned about the availability, cost, and security associated with the use of public
Wi-Fi networks.
4G Wireless Communications
4G stands for fourth-generation broadband mobile wireless, which is expected to deliver
more advanced versions of enhanced multimedia, smooth streaming video, universal access,
portability across all types of devices, and eventually, worldwide roaming capability. 4G will
also provide increased data transmission rates in the 20–40 Mbps range.
Pine Cellular, Pine Telephone, and Choctaw Electric are deploying Nortel 4G technology
to provide homes and businesses in southeastern Oklahoma with reliable, wireless high-speed
Internet. The network will provide low-cost, broad coverage and deliver wireless services to
rural areas where construction of a wired network is less economical. The 4G services will be
provided at no charge to the local police and fire departments and public schools. 23

10. Worldwide Interoperability for
Microwave Access (WiMAX)
The common name for a set of IEEE
802.16 wireless metropolitan area
network standards that support different
types of communications
access.
Future Wireless Communications Developments
digital signal
A signal that represents bits.
analog signal
A variable signal continuous in both
time and amplitude so that any
small fluctuations in the signal are
meaningful.
NETWORKS AND DISTRIBUTED PROCESSING
Network Types
computer network
The communications media,
devices, and software needed to
connect two or more computer
systems or devices.
personal area network (PAN)
A network that supports the
interconnection of information
technology within a range of 33 feet
or so.
local area network (LAN)
A network that connects computer
systems and devices within a small
area, such as an office, home, or
several floors in a building
metropolitan area network
(MAN)
A telecommunications network that
connects users and their devices in
a geographical area that spans a
campus or city.
wide area network (WAN)
A telecommunications network that
ties together large geographic
regions.

11. Basic Processing Alternatives
centralized processing
Processing alternative in which all
processing occurs at a single location
or facility.
decentralized processing
Processing alternative in which processing
devices are placed at various
remote locations.
distributed processing
Processing alternative in which
computers are placed at remote
locations but are connected to each
other via a network
File Server Systems
Users can share data through file server computing, which allows authorized users to download
entire files from certain computers designated as file servers. After downloading data to
a local computer, a user can analyze, manipulate, format, and display data from the file (see
client/server
An architecture in which multiple
computer platforms are dedicated
to special functions such as
database management, printing,
communications, and program
execution.
Telecommunications and Networks
| Chapter 6 239
register operations, gasoline pump monitoring, and merchandising.
Telecommunications Hardware
modem
A telecommunications hardware
device that converts (modulates
and demodulates) communications
signals so they can be transmitted
over the communication media.
multiplexer
A device that combines data from
multiple data sources into a single
output signal that carries multiple
channels, thus reducing the number
of communications links needed
and therefore, lowering telecommunications
costs.
front-end processor
A special-purpose computer that
manages communications to and
from a computer system serving
hundreds or even thousands of
users.
private branch exchange (PBX)
A telephone switching exchange
that serves a single organization.
switch
A telecommunications device that

12. uses the physical device address in
each incoming message on the network
to determine to which output
port it should forward the message
to reach another device on the same
network.
bridge
A telecommunications device that
connects one LAN to another LAN
using the same telecommunications
protocol.
router
A telecommunications device that
forwards data packets across two or
more distinct networks toward their
destinations, through a process
known as routing.
gateway
A telecommunications device that
serves as an entrance to another
network.
Telecommunications Software
network operating system
(NOS)
Systems software that controls the
computer systems and devices on a
network and allows them to communicate
with each other
network-management
software
Software that enables a manager on
a networked desktop to monitor the
use of individual computers and
shared hardware (such as printers),
scan for viruses, and ensure compliance
with software licenses
Securing Data Transmission
encryption
The process of converting an original
message into a form that can
only be understood by the intended
receiver.
Securing Wireless Networks
Wired equivalent privacy (WEP)
An early attempt at securing wireless
communications based on
encryption using a 64- or 128-bit key
that is not difficult for hackers to
crack.
Wi-Fi Protected Access (WPA)
A security protocol that offers
significantly improved protection
over WEP.

13. Other Encryption Methods
Data Encryption Standard
(DES)
An early data encryption standard
developed in the 1970s that uses a
56-bit private key algorithm.
Advanced Encryption Standard
(AES)
An extremely strong data encryption
standard sponsored by the National
Institute of Standards and Technology
based on a key size of 128 bits,
192 bits, or 256 bits
Virtual Private Network (VPN)
virtual private network (VPN)
A private network that uses a public
network (usually the Internet) to
connect multiple remote locations.
TC services and network Application