computing
ESSENTIALS

7
Connectivity, the
Wireless Revolution,
and
Communications
Copyright 2003 The McGraw-Hill Companies,
Inc.Copyright 2003 The McGraw-Hill
Companies, Inc.
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computing

ESSENTIALS
Competencies
Connectivity
Wireless Revolution
Communication systems
Connection devices
Transmissions and protocols
Network architecture
Copyright 2003 The McGraw-Hill Companies,
Inc.
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computing
ESSENTIALS

Connectivity

Computer networks
that link people and
resources

Other computers

Large storage
devices

Internet
Copyright 2003 The McGraw-Hill Companies,
Inc.
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computing

ESSENTIALS
Wireless Revolution



Wireless and mobile
telephones
 Most dramatic change in
connectivity
 Connected all the time
anywhere
Originally voice
communication
Computer communications
 Bluetooth
 Device connections
Copyright 2003 The McGraw-Hill Companies,
Inc.
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computing
ESSENTIALS

Communication Systems

Electronic systems that transmit and receive
information

Basic elements

Sending/Receiving device

Communication channel

Connection devices

Data transmission specifications
Copyright 2003 The McGraw-Hill Companies,
Inc.
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computing
ESSENTIALS

Communication Channels

Essential element of communication system

Two categories

Physical connection

Wireless connection
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Inc.
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computing

ESSENTIALS
Wired Connections

Telephone lines
 Twisted pair
 Old standard
• Coaxial cable
– Single solid-copper core
– 80 times faster
• Fiber-optic cable
– Light through glass
– 26,000 times faster
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Inc.
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computing
ESSENTIALS

Wireless Connections


Microwave
 High-frequency radio waves
 Line-of-sight communication
 Relayed
Satellite
 Microwave relay stations
 Geostationary
 Large volume of data
Copyright 2003 The McGraw-Hill Companies,
Inc.
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computing
ESSENTIALS

Connection Devices






Modulator-demodulator
 Converts analog signal to digital signal
Speed in bits per second (bps)
External
Internal
PC Card
Wireless
Copyright 2003 The McGraw-Hill Companies,
Inc.
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computing
ESSENTIALS

Connection Types





Dial-up service
 Most popular, but slow
T1 – T4 lines
 Special high-speed lines
Digital subscriber line (DSL)
 Uses existing phone lines, fast
Cable
 Existing television cables
Satellite/air connection services
 Slower than DSL, but faster than dial-up
Copyright 2003 The McGraw-Hill Companies,
Inc.
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computing
ESSENTIALS

Data Transmission

Bandwidth
 How much information can be transmitted
at one time

Protocol
 Specific rules guiding the exchange of
information
Copyright 2003 The McGraw-Hill Companies,
Inc.
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computing
ESSENTIALS

Bandwidth


Measurement of capacity of the
communication channel
Categories
 Voiceband
 Standard phone line, dial-up
 Medium band
 Special leased lines
 Broadband
 High capacity transmissions
 DSL, cable, satellite
Copyright 2003 The McGraw-Hill Companies,
Inc.
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computing
ESSENTIALS

Data Transmission Direction

Simplex


Half-duplex


One direction only
One direction at a time
Full-duplex

Both direction simultaneously
Copyright 2003 The McGraw-Hill Companies,
Inc.
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computing
ESSENTIALS

Protocols


Set of communication rules for exchange of
information
Transmission control protocol/Internet
protocol (TCP/IP)
 Identification
 IP Address
 Domain name system (DNS)
 Reformatting
 Reassemble packets
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computing
ESSENTIALS

Networks




Two or more connected computers that share
information and resources
Node
 Device connected to a network
Client
 Node that requests and uses resources
available from other nodes
Server
 Node that shares resources with other
nodes
Copyright 2003 The McGraw-Hill Companies,
Inc.
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computing
ESSENTIALS

More Network Terms



Network operating system (NOS)
 Software to control and coordinate activities
between nodes on a network
Distributed processing
 Computing power located and shared at
different locations
Host computer
 Large centralized computer, usually a
mainframe
Copyright 2003 The McGraw-Hill Companies,
Inc.
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computing
ESSENTIALS

Network Architecture



Arrangement of network communication
channel
Coordinates and shares resources
Topology
 Star network
 Bus network
 Ring network
 Hierarchical
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Inc.
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computing
ESSENTIALS

Star Network
Copyright 2003 The McGraw-Hill Companies,
Inc.
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computing
ESSENTIALS

Bus Network
Copyright 2003 The McGraw-Hill Companies,
Inc.
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computing
ESSENTIALS

Ring Network
Copyright 2003 The McGraw-Hill Companies,
Inc.
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computing
ESSENTIALS

Hierarchical Network
Copyright 2003 The McGraw-Hill Companies,
Inc.
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computing
ESSENTIALS

Strategies

Ways to coordinate sharing of resources

Most common

Terminal network system

Peer-to-peer network system

Client/Server network system

Enterprise computing
Copyright 2003 The McGraw-Hill Companies,
Inc.
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computing
ESSENTIALS

Network Types

Networks differ in geographical size

Types of networks

Local Area Network (LAN)

Metropolitan Area Network (MAN)

Wide Area Network (WAN)
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Inc.
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computing
ESSENTIALS

Local Area Networks

Computers and devices linked in close
proximity to each other

Typically use a bus form of organization

Network gateways

Network bridge
Copyright 2003 The McGraw-Hill Companies,
Inc.
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computing
ESSENTIALS

Metropolitan Area Networks

Link nodes and resources within the
geographical bounds of a city

Link between buildings

Cellular phones can extend the reach of a MAN
Copyright 2003 The McGraw-Hill Companies,
Inc.
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computing
ESSENTIALS

Wide Area Networks

Countrywide and worldwide network

Use microwave relays and satellites

Internet

Widest of all WAN
Copyright 2003 The McGraw-Hill Companies,
Inc.
26
computing

ESSENTIALS
Look to Future


Wireless robotic car
Toyota and Sony collaboration
 Pod
 Connects wirelessly to portable terminal
 Download


songs from Internet
Use GPS to determine location
Communicate with other cars
Copyright 2003 The McGraw-Hill Companies,
Inc.
27