Wired and wireless communication

8/4/2019 Wired and wireless communication

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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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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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Bandwidth andM

odemsBandwidth andM

odems Digital signal sampling



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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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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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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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Bandwidth andM

odemsBandwidth andM

odems



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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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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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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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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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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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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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ediaM

edia



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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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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





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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





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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





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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





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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





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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)





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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.





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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





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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





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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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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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ApplicationsApplications



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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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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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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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ApplicationsApplications Text messaging

(SMS)o Using cell phone for

applications previouslyusedon computers

o Instant messaging

o Brief e-mail



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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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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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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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permission of the publisher. Printed in the United States of America.

Copyright 2012 Pearson Education Inc Publishing as Prentice Hall 54

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Wired and wireless communication