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Computers Are Your FutureComputers Are Your Future
Twelfth EditionTwelfth Edition
Chapter 8: Wired and Wireless Communication
Copyright 2012 Pearson Education, Inc. Publishing as Prentice Hall 1
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Wired and WirelessWired and Wireless
CommunicationCommunication
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ObjectivesObjectives Differentiate between bandwidth andthroughput, and discuss the bandwidthneeds of typical users.
Discuss how modems transform digitalcomputer signals into analog signalsand analog into digital.
List various physical and wirelesstransmission media and explain severaltransmission methods.
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ObjectivesObjectives Explain the limitations of the publicswitched telephone network (PSTN) forsending and receiving computer data.
Describe digital telephony andmultiplexing, including their impact online usage.
Discuss last-mile technologies thatconnect users with their communicationproviders.
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ObjectivesObjectives Provide examples of how digitization
and convergence are blurring the
boundaries that distinguish popularcommunications devices, includingphones and computers.
Discuss various wired and wirelessapplications.
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Moving Data:Moving Data:
Bandwidth andM
odemsBandwidth andM
odems Communications
o Process of sending and receiving messageselectronically between two points
o Sending deviceinitiates the transmissiono Receiving deviceaccepts the transmission and
responds
Communications channelo Path to send and receive messages
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Moving Data:Moving Data:
Bandwidth andM
odemsBandwidth andM
odems Analog signalso Continuous waves
Digital signalso Discontinuous, discrete pulses
Converterso Translate signals:
Analog-to-digital converter (ADC)
Digital-to-analog converter (DAC)
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Moving Data:Moving Data:
Bandwidth andM
odemsBandwidth andM
odems Digital signal sampling
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Moving Data:Moving Data:
Bandwidth andM
odemsBandwidth andM
odems Bandwidtho The maximum amountof data transmitted through a
communication channel atone time
Throughputo The actual amountof data transmitted
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Moving Data:Moving Data:
Bandwidth andM
odemsBandwidth andM
odems Broadband
o Any transmission medium that carries several
channels transporting data athigh speeds
Streamingo The ability tohear or see content while it is being
downloaded from a Web site
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Moving Data:Moving Data:
Bandwidth andM
odemsBandwidth andM
odems Modem
o A communication device used to send and receive
datao The term modem comes from modulate and
demodulate.
The sender uses modulation to transmitdigital
signals. The receiver uses demodulation to return signals
todigital form.
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Moving Data:Moving Data:
Bandwidth andM
odemsBandwidth andM
odems
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Moving Data:Moving Data:
Bandwidth andM
odemsBandwidth andM
odems Types of modemso Analog
o Digital subscriber line (DSL)
o Cable
o Integrated Services Digital Network (ISDN)
Data transferrateo Rate at which two modems exchange data
o Measured in bits per second(bps)
Baudo Number of signaling elements per second
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Wired TransmissionWired TransmissionM
ediaM
edia Wiring closet Houses wiring that supports most types ofdata
transfer needed
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Wired TransmissionWired TransmissionM
ediaM
edia Twisted-pair wire
Copper wire used for
telephone anddatacommunication
o Twopairs of interweavedwires twisted together
o
Inexpensive, but bandwidthtoo low for video, voice, anddata at the same time
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Wired TransmissionWired TransmissionM
ediaM
edia Keyvariations of twisted-wire
pairo Category 5 (Cat-5)
o Category 5 enhanced (Cat-5e)
o Category 6 (Cat-6)
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Wired TransmissionWired TransmissionM
ediaM
edia Coaxial cable
o Consists of copper wire
surrounded by insulation andbraided wire
Broadband communication
Cable TV
10 Mbps transfer rate
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Wired TransmissionWired TransmissionM
ediaM
edia Fiber-optic cable
o Consists of thin strands of
glass or plastic that carrydata throughpulses of light
Broadbandcommunication
10 Gbps transfer rate
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Wireless TransmissionWireless TransmissionM
ediaM
edia Infrared
o Wireless transmission
medium that carries datathrough the air using lightbeams
o Sending and receivingdevices must be in line of
sighto Uses an IrDA port to
enable data transfer
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Wireless TransmissionWireless TransmissionM
ediaM
edia Radio transmission
o Enables music, photos, and voice to travel throughthe air as radio frequency or radio waves
o Bluetoothradio transmission enables deviceswithin 30 feet to communicate wirelessly
o Does not require direct line of sight
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Wireless TransmissionWireless TransmissionM
ediaM
edia
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Wireless TransmissionWireless TransmissionM
ediaM
edia Microwaves
o Transmitdata via
electromagnetic radiowaves with shortfrequencies
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Wireless TransmissionWireless TransmissionMM
ediaedia Satellites
o Microwave relay stations in space that transmitdata
through microwave signalso Direct broadcast satellite (DBS)consumer
satellite technology that receives digital TV signalsthrough a reception dish
o Requires the computer system tohave a specialcommunications device called a network accesspointsends and receives data between computerthat contain wireless adapters
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Wired CommunicationWired Communication
via the PSTNvia the PSTN Public switched telephone network (PSTN)o Worldwide telephone system used for data
and voice communications
o Primarily digital
Subscriberloop carrier (SLC)o Links home and business telephones
o Accommodates analogdevices
Localloopo Area served by an SLC
Localexchange switcho Digital device capable ofhandling thousands of calls
o Located at the local telephones central office
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Wired CommunicationWired Communication
via the PSTNvia the PSTN
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Digital telephonyo Telephones and transmissions are digital
o Companiesuse a private branch exchange (PBX)
Multiplexingo Allows multiple calls over a single line
o Long-distance carrierstransmit many calls indigital format in a single circuit
Wired CommunicationWired Communication
via the PSTNvia the PSTN
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Last-mile problemo Inability to access the PSTNs high-speed, fiber-optic
cableso Bottleneck ofdata on the last mile of twisted-pairphone lines
Last-mile technologieso Provide solutions for bottlenecks
o Used while local loops are upgraded
Wired CommunicationWired Communication
via the PSTNvia the PSTN
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Last-mile technologies (cont.)o Integrated services digital networking (ISDN)
Standard thatprovides digital telephone anddataservice
No lengthy dial-in procedures or connection delay
Requires an ISDN adapter/digital modem to
connect computers to ISDN lines May be the only broadband solution in rural areas
Wired CommunicationWired Communication
via the PSTNvia the PSTN
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Last-mile technologies (cont.)o Digital subscriberline (DSL) (Also calledxDSL)
Broad term for groupof technologies offeringhigh-speed
accessoADSL (asymmetric digital subscriberline)
o SDSL (symmetric digital subscriberline)
o HDSL (high bit-rate digital subscriberline)
oVDSL (very high bit-rate digital subscriberline)
Requires DSL modemmodulate anddemodulate analoganddigital signals
More expensive than dial-upcheaper than other broadbandoptions
Wired CommunicationWired Communication
via the PSTNvia the PSTN
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Wired CommunicationWired Communication
via the PSTNvia the PSTN
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Last-mile technologies (cont.)o Cable-based broadband
Provides Internet access through cable TV
connections
Uses cable modems toobtain higher speedsthan DSL
o Leased lines
Specially conditioned telephone lines between twopoints
o Example: T1lines
Wired CommunicationWired Communication
via the PSTNvia the PSTN
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Last-mile technologies (cont.)o T2and T3lines
o SONET (synchronous optical network)
o MMDS (Multichannel multipoint distributionservice)
o WiMAX (Worldwide interoperability formicrowave access)
Wired CommunicationWired Communication
via the PSTNvia the PSTN
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Convergence: Is It aConvergence: Is It a
Phone or a Computer?Phone or a Computer? Digitization
o Process of transforming
data into a digital form Convergenceo Blendingo Multiple industries
Examples: Computers,
consumer electronics,telecommunications
o Productso Examples: Personal
computers, telephones
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Cellular telephoneso Digital transmission of voice, text, images, and
video
o Classified by generations4G (fourthgeneration)the currentgeneration
o Cell sitesnetwork of transmitters broadcastssignals throughoutgeographic areas calledcells
Convergence: Is ItConvergence: Is It AA
Phone orPhone or AA Computer?Computer?
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Each cellular network includes multiple mobileswitching centers (MSCs) that controlcommunication within a setof cells.
Convergence: Is ItConvergence: Is It AA
Phone orPhone or AA Computer?Computer?
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Personal communication service(PCS)oGroupofdigital cellular technologies replacing most
analog cellular serviceso2G (secondgeneration)used to make
smartphones, with features ofphones andcomputingdevices
o3Gmore data and voice customers andhigher datatransfer rates
o4Gimproved connectivity, data transfer rates, andsupport for the nextgeneration of multimedia
Convergence: Is It AConvergence: Is It A
Phone or A Computer?Phone or A Computer?
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Web-enableddeviceso Display and respond to
markup languages
Examples: HTML, XMLused to build Web pages
o Examples
PDA
s SmartphonesreplacingPDAs
Notebooks
Convergence: Is ItConvergence: Is It AA
Phone orPhone or AA Computer?Computer?
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WAP (Wireless ApplicationProtocol)o Standardspecifies how users can access the
Web securely using:
Pagers
Smartphones
PDA
s Other wireless devices
o Requires a microbrowser
Convergence: Is ItConvergence: Is It AA
Phone orPhone or AA Computer?Computer?
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Wired and WirelessWired and Wireless
ApplicationsApplications Internet telephony, or VoIP(Voice overInternet Protocol)o
Offers computer-to-phone andphone-to-phonetransmission through the Internet
o Placing calls requires:
Computer with a microphone, speakers orheadphones
Internet connection
Telephony-enabledprogram
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Wired and WirelessWired and Wireless
ApplicationsApplications Internet telephonyoVideoconferencing (Web conferencing)
transmits sound and video images using:
Video camera (Webcams) Skype software
o Whiteboardsenable participants to create ashared workspace
o Webcamsinexpensive, low-resolution analogordigital video cameras
o Internet TVability to view television shows,videos, and movies over the Internet
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Wired and WirelessWired and Wireless
ApplicationsApplications
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Wired and WirelessWired and Wireless
ApplicationsApplications Facsimile transmission (fax)
o Transmits documents over a telephone line or the
Internetusing either: Standalone fax machine
Computer with a fax modem and a scanner
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Wired and WirelessWired and Wireless
ApplicationsApplications Satellite technology
o Satelliteradio
Not affected by location, distance, or obstructions Uses satellites orbiting the Earth
Permits usage in areas with restricted local radiostations or poor AM/FM reception
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Wired and WirelessWired and Wireless
ApplicationsApplications Satellite technology (cont.)
o GPS (GlobalPositioning System)
System of 27 satellites allowing a receiver topinpoint locations
Mobile units for cars
Installed car systems
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Wired and WirelessWired and Wireless
ApplicationsApplications
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Wired and WirelessWired and Wireless
ApplicationsApplications
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Wired and WirelessWired and Wireless
ApplicationsApplications Text messaging
(SMS)o Using cell phone for
applications previouslyusedon computers
o Instant messaging
o Brief e-mail
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Wired and WirelessWired and Wireless
ApplicationsApplications Picture messaging
o MMS(multimedia messaging system)o
Transmits color pictures and backgroundso Cellular telephone acts as a camera
Location awarenesso Also known as position awarenesso
Uses GPS-enabled chips topinpoint the location of acell phoneo Popular withparents of teenagers
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Wired and WirelessWired and Wireless
ApplicationsApplications Surfing safely at public wirelesshot spots
o Malicious network(evil twin)network setup by ahacker within the operating area of a legitimate hotspot
o Use firewalls and antivirus software
o Use legitimate networks to avoid evil twins
o Do notperform financial transactions
o Select appropriate operating system settings to avoidbeingdetected
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Wired and WirelessWired and Wireless
ApplicationsApplications
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SummarySummary
Differentiate between bandwidth andthroughput, and discuss the bandwidthneeds of typical users.
Discuss how modems transform digitalcomputer signals into analog signals andanalog into digital.
List various physical and wirelesstransmission media and explain severaltransmission methods.
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SummarySummary
Explain the limitations of the publicswitched telephone network (PSTN) forsending and receiving computer data.
Describe digital telephony andmultiplexing, including their impactonline usage.
Discuss last-mile technologies thatconnectusers with their communicationproviders.
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SummarySummary Provide examples ofhow digitization
and convergence are blurring the
boundaries thatdistinguishpopularcommunications devices, includingphones and computers.
Discuss various wired and wirelessapplications.
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All rights reserved. No part of this publication may be reproduced, stored in a
retrieval system, or transmitted, in any form orby any means, electronic,
mechanical, photocopying, recording, or otherwise, without the prior written
permission of the publisher. Printed in the United States of America.
Copyright 2012 Pearson Education Inc Publishing as Prentice Hall 54