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© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved.
9-3
Competencies
Discuss connectivity, the wireless revolution, and communication systems
Describe physical and wireless communications channels
Discuss connection devices
Describe data transmission factors
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Competencies cont.
Discuss networks and key network terminology
Describe the different types of networks
Describe network architectures
Describe organizational uses of Internet technologies
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What is Communication?
The process of sharing data, programs, and information between two or more computers
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Communications Today
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Cont.
Applications that depend on the Communication Systems: email, instant messaging, internet telephone and electronic commerce.
Connectivity: is a concept related to using computer networks to link people and resources.
( you can connect your microcomputer by telephone or other telecommunication link to other computers).
Wireless revolution: Allow devices to communicate with one another without any physical connection
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Communication Systems Are electronic systems that transmit data from one location to another
Basic elements of a communication system:
1- Sending and Receiving Devices ( computers or specialized communication devices).
2- Communication Channel( transmission medium) (physical wire or cable and wireless connection).
3- Connection Devices (communication devices): Act as an interface between the sending and receiving devices and the communication channel, they convert outgoing message into a form and format so that they can travel across the communication channel.
4- Data Transmission specifications: rules and procedures that coordinate the sending and receiving devices( how the message will be send through the communication channel)
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Communication Systems
Computer
Modem
Telephone-lines
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Communication Channels
Channels carry data from one computer to
another
Two categories of communication channels
Physical connection
Wireless connection
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Physical ConnectionsSolid medium to connect sending and receiving devices
Telephone lines ( twisted pair cable)
Coaxial cablehigh frequency transmission cable
deliver television signals and connect computer in a network.
80 times the transmission capacity of twisted pair cable
Fiber-optic cable Transmit data as pulses of light through tiny tubes of glass.
26000 times the transmission capacity of twisted pair cable
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Wireless Connections
InfraredBroadcast radio: Communication uses special sending and receiving towers called Transceivers, send and receive radio signals from wireless devices
Microwave: Communication uses high frequency radio waves
sending data between buildings in a city
Stations used for long distance
Bluetooth
SatelliteUplink/Downlink
Uplink is a term of sending data to a satellite.Downlink is a term of receiving data from a satellite.
Global Positioning System: Application of satellite communication
Note: Check page 239Video.edhole.com
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More on Satellites
Global positioning Network of 24 satellites
Owned by the Defense Department
Global positioning system (GPS)Devices used to determine location
Provides navigational support
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Connection Devices
Types of signalsAnalog
Digital
Types of modemsInternal: plug-in circuit boardExternal: wall jack, modem and serial port
PC Card: laptop
Wireless
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Types of Connections
Digital subscriber line (DSL)Uses existing phone lines
ADSL (Asymmetric digital subscriber line)
ADSL services can download at up to 8Mb/s and upload up to 832 kb/s,
Cable modemsUses existing TV cable
Provides speeds as fast as DSL at a lower cost
Satellite/air connection services Seven times faster than dial-up
Slower than DSL & cable modemVideo.edhole.com
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User Connection Costs & Speeds
Type Fee Speed Seconds to Get Images
Dial-up $16 56 kbps 45.0
DSL 50 1.5 mbps 1.7
Cable Modem 40 1.5 mbps 1.7
Satellite 70 900 kbps 2.8
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Bandwidth
Measurement of the capacity of the channel
Categories Low bandwidths or Voiceband
Used for standard telephone communication
Medium band Used for minicomputer and mainframe
BroadbandUsed for high capacity transmission
Used by DSL, cable & satellite
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Protocols
Set of communication rules
Rules for exchanging data between computers.
Standard for Internet: TCP/IPTransmission control protocol/Internet protocol
Identifies devices : Identifying sending and receiving devices
Each computer on the internet has IP address
DNS domain name server convert text to IP address.
Reformats information Reformatted or broken into small parts called packets
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Networks
A computer network is a communication system
Connects two or more computers
Allows information exchange
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Network Terms
Node Any device that is connected to a network
(Computer or printer)
Client: microcomputer
ServerA node that shares resources with other nodes
HubThe center or central node for other nodes
Network interface cards (NIC)
Network operating system (NOS)
Distributed processingThis type of system is common in decentralized
organization where divisional offices have their own computer
Host computerMinicomputer or mainframe computer
Network managerComputer specialist or network administrator
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Network Types
Local area networks 1 mile
Home networksIncluding a common internet connection
Metropolitan area networks (MAN)100 miles connect buildings in a city
Wide area networks(WAN)
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Network Architecture
Architecture describes how a network is arranged
Arrangement is called topology
Types of network topologyStar
Bus
Ring
Hierarchical
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Star Network
Smaller computers linked to a central unit
Central unit is called the network hub
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Bus Network
Each device handles its own communication control
There is no host computer
Has a common connecting cable called a backbone
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Ring Network
Each device is connected to two other devices
No central file server or computer
Useful in a decentralized environment
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Hierarchical Network
Several computers linked to a central host
Computers are hosts to other computers
Useful in centralized organizations
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Strategies
Strategy is a way of coordinating the sharing of information and resourcesCommon network strategies
Terminal
Processing power is centralized in one large computer , usually a mainframe.Many airline reservation systems are terminal systems. A large central computer maintain
all the airline schedule.
Client/serverUse one computer to coordinate and supply services to other nodes on the network. The
server provides access to resources such as web pages, database.
Peer-to-peerNodes have equal authority and can act as both clients and servers, for example one
microcomputer can obtain files located on another microcomputer and can also provide files to other microcomputers
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Organizational Internets
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Internets and Extranets
IntranetsPrivate network within an organization
Provides information to employees
ExtranetsPrivate network that connects organizations
Used to allow suppliers and others access
FirewallsSecurity system
Protects against external threats Video.edhole.com
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A Look to the FutureWireless Robotic Car
Pod car (Personalization on Demand)
Predicts and responds
Designed to learn and adapt to an individual's driving needs and habits
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Key Terms
802.11 (239)analog signal (240)application server (243)asymmetric digital subscriber line (ADSL) (241)backbone (249)bandwidth (241)base station (245)bits per second (bps) (240)
Bluetooth (239)
broadcast radio (238)
broadband (242)
bus (249)
bus network (249)
cable modem (241)
cellular phone system (245)
client (243)
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Key Terms
client/server network system (251)
coaxial cable (238)
communications (246)
communication channel (237)
communication device (237)
communication server (243)
communication system (237)
computer network (243)
connection device (237)
connectivity (236)
database server (243)
data transmission specification (237)
dedicated server (243)
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Key Terms
demodulation (240)
dial-up service (240)
digital signal (240)
digital subscriber line (DSL) (241)
dish (239)
Distributed data processing system (249)
distributed processing (243)
Domain name server (DNS) (242)
downlink (239)
external modem (240)
extranet (243)
fiber-optic cable (238)
file server (243)
firewall (253)
Gnutella (252)
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Key Terms
global positioning (239)
global positioning system (GPS) (239)
hierarchical network (249)
home network (245)
host computer (243)
hub (243)
hybrid network (249)
infrared (238)
internal modem (240)
intranet (253)
IP address (Internet Protocol address) (242)
LAN adapter (243)
line of sight communication (238)
Local area network (LAN) (244)
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Key Terms
low bandwidth (241)
medium band (242)
metropolitan area network (MAN) (245)
microwave (239)
microwave station (239)
modem (240)
modulation (240)
Napster (251)
network administrator (243)
network architecture (248)
network gateway (244)
network hub (248)
network interface card (NIC) (243)
network manager (243)
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Key Terms
network operating system (NOS) (243)
node (243)
packet (242)
PC card modem (240)
peer-to-peer network system (252)
polling (248)
printer server (243)
protocol (242)
proxy server (254)
receiving device (237)
regional network (245)
ring network (249)
satellite (239)
Satellite/air connection service (241)
sending device (237)
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Key Terms
server (243)
star network (248)
strategy (250)
TCP/IP (transmission control protocol/Internet protocol) (242)
telephone line (238)
terminal network system (250)
time-sharing system (249)
T1, T2, T3, T4 lines (240)
topology (248)
transceiver (238)
transfer speed (240)
transfer rate (240)
transmission medium (237)
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Key Terms
twisted pair (238)
uplink (239)
voiceband (241)
voice grade (241)
Web server (243)
wide area network (WAN) (245)
Wi-FI (wireless fidelity) (239)
wireless LAN (WLAN) (245)
wireless modem (240)
wireless receiver (245)
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FAQs
What is fiber-optic cable?
My Palm Pilot uses Bluetooth. What is it?
What is a modem?
What is DSL? How does it work?
How fast is broadband bandwidth?
What is a local area network?
What is meant by peer-to-peer?
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Discussion Questions
Discuss what is meant by the wireless revolution.
Discuss the four types of service connections.
Discuss the advantages and disadvantages of the four network topologies.
Explain the connections in a home network.
Describe the different network topologies.
Describe a GPS system.
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