Bài 2. Thông tin và dữ liệu

Communications Communications device — connects the communications channel to the receiving device Receiving device — accepts transmission of data, instructions, or information Communica

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Chapter 9 Communication

s and Networks

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Describe uses of computer communications

List advantages of using a network

Differentiate among client/server,

peer-to-peer, and P2P networks

Differentiate among client/server,

peer-to-peer, and P2P networks

Describe the various network

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What are computer communications?

Next

p 460 Fig 9-1

instructions, and information

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Sending device — initiates instruction to transmit data, instructions, or information

What is needed for successful communications?

Communications

Communications device — connects the communications channel to the receiving device

Receiving device — accepts transmission of data, instructions, or information

Communications device — connects the sending device to the communications

channel

Communications channel — media

on which data, instructions, or information travel

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Internet Telephony

Internet Telephony Newsgroups

Chat Rooms

Web Folders

Fax Machine

or Computer Fax/Modem

Fax Machine

or Computer Fax/Modem

Video Conferencing

Video Conferencing FTP

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Uses of Computer

Communications

What are wireless messaging services?

Wireless instant messaging allows wireless mobile devices to exchange

messages

Text messaging

allows users to send

and receive short

text messages on a

smart phone or

PDA Picture messaging

allows users to send graphics, pictures, video clips, sound files, and short text

messages

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Communications

What are public Internet

access points and

cybercafés?

Next

p 464 Fig 9-5

 Public Internet access

point allows wireless connection to Internet

Click to view Web

Link, click Chapter 9, Click

Web Link from left

navigation, then click

Hot Spots below Chapter 9

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second, each satellite

sends a signal that

indicates its current

position to the GPS

server.

Step 2.

A GPS receiver (such as in a car,

a PDA, a watch,

a handheld device, or a collar) determines its location on Earth

by analyzing at least 3 separate satellite signals from the 24 satellites in orbit.

Click to view Web

Web Link from left

GPS below Chapter 9

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Communications

What are voice mail and web services?

 Voice mail is voice message converted to digital

form

 Web services describe standardized software that

enables programmers to create applications that

communicate with other remote computers over

the Internet

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What is a local area

network (LAN)?

home or office building

 Wireless LAN (WLAN)

 Metropolitan area network (MAN) connects LANs in

city or town

Click to view Web

Web Link from left

Local Area Networks below

Chapter 9

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What is a client/server

network?

act as server and other

computers, or clients,

access server

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exchange files directly

Click to view Web

Web Link from left

P2P below Chapter 9

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What is a ring network?

ring, or loop, with all

computers and devices

arranged along ring

device to device

around entire ring, in

one direction

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What is a star network?

Next

p 475 Fig 9-18

a central device, called

hub

from one computer to

another passes

through hub

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 If two computers send data at same time,

a collision occurs and computers must send again

Token ring technology controls access to network

by requiring devices to pass a special signal, called token

Click to view Web

Web Link from left

Ethernet below Chapter 9

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Network Communications

Standards

What are TCP/IP and 802.11?

 TCP/IP ( T ransmission C ontrol P rotocol/ I nternet

P rotocol) technology transmits data by breaking it up into small pieces, or packets

 802.11 is family of standards for wireless LANs

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specification allows data to be transferred wirelessly via infrared light waves Wireless Applications

Protocol (WAP)

allow wireless mobile devices

to access Internet

Wireless Applications Protocol (WAP)

allow wireless mobile devices

to access Internet

Radio Frequency Identification (RFID)

uses radio signals to communicate with a tag placed in an object

Radio Frequency Identification (RFID)

uses radio signals to communicate with a tag placed in an object

Click to view Web

Link, click Chapter 9,

Click Web Link from left

WAP below Chapter 9

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Video: Keep Tabs on Your Pets

Discover how to improve the odds of recovering a lost or

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Communications Software

What is communications software?

Programs that help users

establish connection to

Internet, other network,

or another computer Programs that help users

manage transmission of data, instructions,

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Communications Over the Telephone Network

What is the public switched

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What is a dial-up line?

using telephone line for

communications

 Costs no more than

making regular call

 Computers at any

two locations can establish a

connection using modems and

telephone network

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What is a dedicated line?

Next

p 482 Fig 9-24

 Four types are ISDN

line, DSL, T-carrier line, and ATM

 Always-on connection

between two communications devices

Click to view Web

Web Link from left

DSL below Chapter 9

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Communications Devices

What are examples of communications devices?

Common types are dial-up modems, ISDN and DSL modems, cable modems, network cards, wireless access points, routers, and hubs

ISDN and DSL modems send and receive data from ISDN

and DSL lines

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What is a dial-up modem?

Next

p 485 Figs 9-27

 Converts digital signals to analog signals and vice versa

 Notebook computers often use PC Card modem

Click to view Web

Web Link from left

Dial-Up Modems

below Chapter 9

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What are ISDN and DSL modems?

Communications devices that send and receive digital ISDN and DSL signals

Usually external devices in which one end connects to a telephone line and the other end connects to a port on the system unit

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What is a cable modem?

Next

p 485 - 486 Fig 9-28

 Sends and receives

data over cable

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What is a wireless modem?

 Allows access to the Web

wirelessly from a

notebook computer, a

PDA, a smart phone, or

other mobile device

same waves used by

cellular telephones

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What is a network card?

Next

p 486 Fig 9-30

 Adapter card, PC Card,

or compact flash card

that enables computer or

device to access network

network interface

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available path

Click to view Web

Web Link from left

Hardware Firewalls below

Chapter 9

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What is a hub?

point for cables in network

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use electrical lines in house

Click to view Web

Web Link from left

Home Networks

below Chapter 9

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Communications Channel

What is a communications channel?

communications system

Bandwidth is amount of data that can travel

over channel

Transmission media

are materials capable of

carrying one or more

signals

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Step 1 The sending device

requests information using either

a physical transmission media

or a wireless transmission media.

Step 2. When the request leaves the ISP, it travels over T1 lines, microwave stations, earth-based stations, and communications satellites until it reaches the Internet backbone.

Step 3 The request travels over

T3 lines along the Internet backbone.

Step 4. The Request travels over T1 lines until it reaches the destination network server.

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Physical Transmission Media

What is physical transmission media?

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What are twisted-pair cable and coaxial cable ?

Next

p 493 Fig 9-37—9-38

 Twisted-pair cable is used for telephone systems and network cabling

 Coaxial cable is often used for cable television wiring

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What is fiber-optic cable ?

 Capable of carrying

significantly more

data at faster speeds

than wire cables

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Wireless Transmission Media

What is wireless transmission media?

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What are broadcast radio and cellular radio?

distributes radio signals over long and short distances

is form of broadcast radio used for mobile communications

Click to view Web

Web Link from left

Cellular Communications below

Chapter 9

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What is a microwave station?

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What is a communications satellite?

signals, and broadcasts

signals back to any

number of earth-based

stations

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Summary of Communications and

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