Computers Are Your Future Eleventh Edition Chapter 8: Wired & Wireless Communication Copyright ©...

Computers Are Your FutureEleventh Edition

Chapter 8: Wired & Wireless Communication

Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall 1

2

All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic,

mechanical, photocopying, recording, or otherwise, without the prior written permission of the publisher. Printed in the United States of America.

Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall

Wired & Wireless Communication

3Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall

Objectives Define bandwidth and discuss the

bandwidth needs of typical users. Discuss how modems transform

digital computer signals into analog signals.

List transmission media and explain several transmission methods.


Objectives Explain the limitations of the public

switched telephone network (PSTN) for sending and receiving computer data.

Describe multiplexing and digital telephony, including their impact online usage.Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall 5

Objectives Provide examples of how

digitization and convergence are blurring the boundaries that distinguish popular communications devices, including phones and computers.

Discuss various wired and wireless applications.Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall 6

Moving Data: Bandwidth and Modems

Communications is the process of sending and receiving messages electronically between two points.

A communications channel is a path used to send and receive messages.



Analog signals are continuous waves.

Digital signals are discontinuous, discrete pulses.

Converters translate signals.


Moving Data:Bandwidth and Modems


Digital signal sampling


Bandwidth is the maximum amount of data transmitted through a communication channel at one time.

Throughput is the actual amount of data transmitted.

Broadband is any transmission medium that carries several channels to transport data at high speeds.



A modem is a communication device used to send and receive data between different transmission systems. The sender uses modulation to

transmit digital signals. The receiver uses demodulation to

return signals to digital form. The term modem comes from

modulate and demodulate.Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall 11


Types of modems Analog Digital subscriber line (DSL) Cable Integrated Services Digital Network

(ISDN) The data transfer rate—the rate

at which two modems exchange data—is measured in bits per second (bps).


Wired Transmission Media Twisted pair wire is copper wire used

for telephone and data communication. Two pairs of interweaved wires twisted

together Inexpensive, but bandwidth too low for

video, voice, and data at the same time


Wired Transmission Media


Coaxial cable consists of copper wire surrounded by insulation and braided wire. Broadband

communication Cable TV 10 Mbps transfer rate

Wired Transmission Media

Fiber-optic cable consists of thin strands of glass or plastic that carry data through pulses of light. Broadband

communication 10 Gbps transfer rate


Wireless Transmission Media

Sending and receiving devices must be in line of sight.

Use an IrDA port to enable data transfer.


Infrared is a wireless transmission medium that carries data through the air using light beams.


Radio transmission enables music, photos, and voice to travel through the air as radio frequency or radio waves. Bluetooth radio transmission

enables devices within 30 feet to communicate wirelessly.

Does not require direct line of sight.



Microwaves transmit data via electromagnetic radio waves with short frequencies.



Satellites are microwave relay stations in space that transmit data through microwave signals. Direct broadcast satellite (DBS) is a

consumer satellite technology that receives digital TV signals through a reception dish.


Wired Communication via the PSTN

Public switched telephone network (PSTN) Worldwide telephone system used for data

and voice communications Primarily digital

Subscriber loop carrier (SLC) Links home and business telephones Accommodates analog devices

Local loop is the area served by an SLC.


Digital telephony Telephones and transmissions are

digital. Companies use a private branch

exchange (PBX). Multiplexing

Allows multiple calls over a single line.

Long-distance carriers transmit many calls in digital format in a single circuit.



Last-mile technologies Provide solutions for bottlenecks that

result from the inability of users to access the PSTN’s high-speed fiber-optic cables

Used while local loops are upgraded



Last-mile technologies Integrated services digital

networking (ISDN) Standard that provides digital telephone and

data service 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

areasCopyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall 26


Last-mile technologies Digital subscriber line (DSL)

Broad term for a group of technologies that offer high-speed access to the Internet

Requires a DSL modem to modulate and demodulate analog and digital signals

More expensive than dial-up but cheaper than other broadband options



Last-mile technologies Cable-based broadband

Provides Internet access through cable TV connections

Uses cable modems to obtain higher speeds than DSL

Leased lines Specially conditioned telephone lines,

such as T1 lines, between two points



Last-mile technologies T3 lines SONET (synchronous optical

network) MMDS (Multichannel multipoint

distribution service) WiMax (Worldwide

interoperability for microwave access)



Convergence: Is It a Phone or a Computer?

Convergence is blending: Multiple industries such as

computers, consumer electronics, and telecommunications

Products such as personal computers and telephones


Digitization is the process of transforming data into a digital form.

Cellular telephones Digital transmission of voice, text,

images, and video. Classified by generations; 3G (third

generation) is the current generation. A network of transmitters called cell

sites broadcasts signals throughout geographic areas called cells.



Each cellular network includes multiple mobile switching centers (MSCs) that control communication within a set of cells.



Personal communication service (PCS) is a group of digital cellular technologies that replaced most analog cellular services.

2G (second generation) design specifications used to make smartphones, which combine the features of phones and computing devices.

3G supports more data and voice customers and higher data transfer rates.



Web-enabled devices Display and respond to markup

languages, such as HTML and XML, that are used to build Web pages.

Examples PDAs Smartphones Notebooks



Web-enabled devices



Wired and Wireless Applications

Internet telephony, or VoIP (Voice over Internet Protocol) Offers computer-to-phone and phone-

to-phone transmission through the Internet

Placing calls requires: A computer with a microphone and

speakers or headphones An Internet connection A telephone-enabled programCopyright © 2011 Pearson Education, Inc. Publishing as Prentice

Hall 37



Internet telephony Videoconferencing transmits sound

and video images to people in different locations using:

Video camera Skype software


Facsimile transmission (fax) transmits documents over a telephone line or the Internet using either: A standalone fax machine, or A computer with a fax modem and a

scanner



Satellite technology Satellite radio

Is not affected by location, distance, or obstructions

Uses satellites orbiting the Earth Permits usage in areas with restricted

local radio stations or bad AM/FM reception



Satellite technology GPS (Global Positioning System)

A system of 27 satellites that allows a GPS receiver to pinpoint a location

Mobile units for cars Installed car systems, such as OnStar



Text messaging is using a cell phone for applications previously used on computers Instant messaging Brief e-mail


Text and picture messaging


Picture messaging Transmits color pictures and

backgrounds Cellular telephone acts as a camera


Text and picture messaging


Surfing safely at public wireless hot spots Use firewalls and antivirus software. Use legitimate networks to avoid “evil

twins.” Do not perform financial transactions. Select appropriate operating system

settings to avoid being detected.


Summary

Bandwidth refers to the maximum data transfer capacity of a communication channel.

Modems are used to modulate and demodulate data sent over dial-up phone lines.

Communications involve both wired and wireless media.


Summary

Use of the PSTN, which is mostly digital, is decreasing because of the increase in the use of broadband alternatives.

Multiplexing is the sending of multiple telephone calls or messages on a single line.


Summary

Digitization is the conversion of voice, text, graphic, audio, and video data into a digital format.

Convergence is the merging of products, such as phones and computers.


Summary

Traditional wired technology can be used for VoIP and faxing, whereas wireless technology makes text and picture messages, satellite radios, and GPS services possible.


Computers Are Your Future Eleventh Edition Chapter 8: Wired & Wireless Communication Copyright ©...

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