Transcript ch05

Chapter 5:
Telecommunications,
Wireless Technologies,
and Computer Networks
Succeeding with Technology:
Second Edition
Objectives
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Understand the fundamentals of data
communications and the criteria for choosing a
communications medium
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Explain how networking media, devices, and
software work together to provide data networking
services, and describe the benefits of various types
of media
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Objectives (continued)
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List and describe the most popular forms of wireless
telecommunications technologies
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List the different classifications of computer
networks and their defining characteristics, and
understand the basics of wireless home networking
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Fundamentals of Telecommunications
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Communications
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Signal
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Transmission of a signal by way of a medium
Contains message comprised of data and
information
Communication medium
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Anything that carries a signal between a sender and
a receiver
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Telecommunications and Data
Communications
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Telecommunications
 Electronic transmission of signals for
communications (Analog or Digital)
Data communications
 Electronic transmission and reception of digital data
Telecommunications network
 Connects communications and computing devices
Networking media
 Anything that carries an electronic signal
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Characteristics of Telecommunications
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Analog signal
 Fluctuates continuously
Digital signal
 Discrete voltage
 State is either high or low
Bandwidth
 Data transmission rate
A misuse of the term
 actually the frequency range transmitted)
Measured in bits per second (bps) (Hertz or Cycles/second)
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Broadband
 Connection that is always on or active and fast
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Networking Media, Devices, and
Software – Networking Media
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Twisted pair cable
 Consists of pairs of twisted wires covered with an
insulating layer
Coaxial cable
 Consists of an inner conductor wire surrounded by
insulation, a conductive shield, and a cover
Fiber-optic cable
 Consists of thousands of extremely thin strands of
glass or plastic bound together in a sheathing
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Networking Devices
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Modems
 Modulates and demodulates signals
 Cable modem
Provides Internet access over a cable television
network (faster due to video bandwidth)
DSL modem
 Provides high-speed Internet service over
telephone lines (uses twisted pair bandwidth)
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Network adapter
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Computer circuit board, PC Card, or USB device
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Network Control Devices
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Hubs
 Used as a central point for connecting a series of
computers - obsolete
Switches
 Fundamental part of most networks
 faster and more versatile than hubs
Repeaters
 Connect multiple network segments
Bridges
 Connect two or more network segments
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Network Control Devices
(continued)
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Gateways
 Network points that act as an entrance to another
network
Routers
 Can divide a single network into two logically
separate networks (usually also a switch)
Wireless access point
 Receives and transmits data to wireless adapters
Firewall
 Device or software that filters the information
coming onto a network
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Industrial Telecommunications
Media and Devices
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Microwave transmission
 Also called terrestrial microwave
 Line-of-sight medium
Communications satellite
 Basically a microwave station placed in outer space
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Industrial Hardware
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T1 line (1.5 Mbits/sec)
 Carries twenty-four 64-Kbps signals on one line
T3 line (45 Mbits/sec)
 Carries 672 signals on one line
Devices commonly used to control and protect
industrial-level telecommunications:
 Multiplexer
 Communications processor
 Encryption devices
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Networking Software
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Monitors the load, or amount of traffic, on the
network
Can provide data security and privacy
Network administrator
 Person responsible for setting up and maintaining
the network
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Networking Software (continued)
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Network Operating Systems
 Perform same functions for network as operating
system software performs for a computer
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Network Management Software
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Facilitates monitoring of individual computers and
shared hardware
Communications Protocols and Standards
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Ethernet: most widely used network standard for
private networks
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Wireless Telecommunications
Technology - Cell Phone
Technologies
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Cellular network
 A radio network
 Geographic area is divided into cells with a
transceiver antenna and station at the center of
each cell
Cellular carrier
 Company that builds and maintains cellular network
 Provides cell phone service to the public
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Cellular Service Plans
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Calling plans are defined by usage in three time
frames:
 Whenever, or anytime, minutes with no time
restrictions
 Weeknight minutes
Monday through Friday, 9:00 p.m. to 5:59 a.m. or
6:59 a.m.
Weekend minutes
 Saturday 12:00 a.m. to Sunday 11:59 p.m.
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Pagers
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Small, lightweight devices that receive signals from
transmitters
Types of paging systems
 National and regional systems
Set up transmission towers to cover large
geographic areas
On-site paging systems
 Use small desktop transmitters to send pages over
a small wireless network
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Global Positioning Systems
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Uses satellites to pinpoint the location of objects on
earth
Using a GPS receiver and a network of 24 satellites
 GPS can tell exact location of receiver on the earth’s
surface
GPS
 Originally developed for national security and later
extended for public use
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Wireless Fidelity and WiMAX
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Wireless fidelity (Wi-Fi)
 Makes use of access points to wirelessly connect
users to networks within a range of 250–1000
 Standards
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Known as the 802.11 family of standards
Developed by the Institute of Electrical and
Electronics Engineers (IEEE)
Developed to support wireless computer networking
within a limited range at broadband speeds
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Wireless Fidelity and WiMAX
(continued)
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WiMAX
 Known as IEEE 802.16
 Faster and longer range than Wi-Fi
 WiMAX antenna has 31-mile range
Perfect for city-wide Internet access
Seattle’s Space Needle has a WiMAX antenna
Intel and Nokia are strongly supporting WiMAX
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Bluetooth
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Enables digital devices to communicate directly with
each other wirelessly over short distances
Communicates at speeds of up to 1 Mbps within a
range of up to 33 feet (10 meters)
Can connect devices to a computer network using
access points like Wi-Fi
Bluetooth and Wi-Fi
 Compete in some areas, but have unique qualities
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Infrared Transmission
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Involves sending signals through the air via light
waves
Slower than both Bluetooth and Wi-Fi
Uses light rather than broadcast technology
Ideal for secure data transmissions
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Radio Frequency Identification
(RFID)
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Uses tiny transponders in tags that can be
 Attached to merchandise or other objects
 Read using an RFID transceiver or reader for the
purpose of identification
 Primarily used to track merchandise from supplier to
retailer to customer
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Networks and Distributed
Computing
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Within a private network
 Computing resources are shared in order to
maximize computing power
Computer
 Includes devices for input, processing, storage, and
output
 Components can be distributed throughout a
computer network
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Computer Networking Concepts
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Nodes
 Devices attached to a network
Workstations
 Computers attached to a network
Local resources
 Files, drives, or other peripheral devices connected
to the workstation and accessible via the network
Network resources
 Workstation accesses over the network
Distributed Computing
 Multiple remote computers working together
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Network Types
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Personal area network (PAN)
 Interconnecting personal information technology
devices
Local Area Network (LAN)
 Connects computer systems within same building
Intranet
 Uses protocols of the Internet and the Web within
the confines of a private network
Virtual Private Network (VPN)
 Enables private Internet communications
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Network Types (continued)
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Metropolitan area network (MAN)
 Connects networks within a city or metropolitan-size
area into a larger high-speed network
Wide area network (WAN)
 Connects LANs and MANs between cities, across
country, and around the world
Global Networks
 A WAN that crosses an international border
Electronic Data Interchange (EDI)
 Connects corporate computer systems
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Home Networks
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Allow residents to
 Share a single Internet connection
 Share a single printer between computers
 Share files such as images, music, and programs
 Back up copies of important files to another PC for
safekeeping
 Participate in multiplayer games.
 Share output from devices such as a DVD player or
Webcam
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Summary
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Telecommunications
 Refers to the electronic transmission of signals for
communication
Types of cables used in telecommunications
 Twisted pair cables, coaxial cable, and fiber optic
cable
Networking devices include
 Modems, network adapters, network control
devices, RFID devices, and pagers
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Summary (continued)
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Cellular network
 Radio network
 Geographic area is divided into cells with a
transceiver antenna (tower) and station at the center
of each cell
Server computers
 Used to distribute data, files, and programs to users,
or clients, on the network
Home networks
 Used to share hardware, files, and a common
Internet connection
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