Chapter 6 Information Technology in Business:

uptightexampleNetworking and Communications

Oct 24, 2013 (3 years and 7 months ago)

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Management Information Systems, 3
rd

Edition

Effy Oz

1

Chapter 6

Information Technology in
Business:
Telecommunications and
Networks

Management Information Systems, 3
rd

Edition

Effy Oz

2

Learning Objectives


When you finish this chapter, you will:


Recognize why successful managers must be
familiar with telecommunications concepts and
terminology.


Know the principles of communication within a
computer system and among computers.


Be able to identify the major media and devices
that are used in telecommunications.

Management Information Systems, 3
rd

Edition

Effy Oz

3

Learning Objectives


Be able to list and explain the functions of
different network layouts and the concept of
protocols.


Understand how telecommunications can
improve operations in organizations.


Know the latest developments in
telecommunications media and transmission
speeds.


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rd

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Telecommunications in Business


Telecommunications


Transmittal of data from one computer to
another over a distance


Telecommunications has improved
business in three main ways:


Better communication


Higher efficiency


Better distribution of data

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rd

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What is Data
Communications?


Data Communications



Any transfer of data within a computer,
between a computer and another device,
or between two computers


Two Basic Modes


Parallel transmission


Serial transmission

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rd

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Communication Direction


Three Modes of Communication Between
Devices


Simplex


One
-
way in one direction


Half
-
Duplex


One
-
way in two directions


Full
-
Duplex


Two
-
way in two directions


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rd

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Communication Direction

Figure 6.2 Simplex, half
-
duplex, and full
-
duplex communication

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Communication Direction


Asynchronous Communication



In asynchronous transmission, the devices are
not synchronized by any timing aids.


Advantage of asynchronous transmission


Does not need sophisticated and expensive timing
hardware


Disadvantage of asynchronous transmission


Overhead, time spent transmitting bits that are not a
part of the primary data



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Communication Modes


Synchronous Communication


In synchronous communication, data are
transmitted using timing devices.


Messages are transmitted in packets.


Advantage of synchronous communication


Overhead in synchronous communication is
significantly smaller than in asynchronous
communication.

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rd

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Communication Modes

Figure 6.4 Synchronous transmission

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Channels and Media


Communication Channel


Physical medium through which data can
be communicated.


Channel Capacity


Narrow band


Broadband

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Channels and Media

Figure 6.5 Transmission speed measurement
unit

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Channels and Media


Media


A medium is any means by which data can be
transmitted.


Transmission speed


A medium’s capacity is determined by the
range of bits per second at which it can operate.

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rd

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Channels and Media

Figure 6.6 Telecommunications transmission speeds of different media

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Channels and Media


Twisted Pair


Telephone line made of a pair of copper wires twisted
to reduce electromagnetic interference (EMI)


Coaxial Cable


Commonly used for cable television transmission


More expensive than twisted pair


Greater transmission rate than twisted pair


Much less susceptible to EMI


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Channels and Media


Microwaves


High
-
frequency, short radio
-
frequency (RF)
waves


Terrestrial microwave


Satellite microwave


Optical Fiber


Fiber
-
optic technology uses light instead of
electricity to transmit data.

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Channels and Media

Figure 6.7 Characteristics of channel media

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Analog vs. Digital


Analog signals


A continuous series of waves


Digital signals


A series of discrete bits

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Modulation


Modification of a digital signal into
an analog signal


Demodulation


Modification of an analog signal into a
digital signal

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Modulation

Figure 6.8 Signal modulation

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Modulation


Amplitude Modulation (AM)



Frequency Modulation (FM)



Phase Modulation


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Modulation


Modems


Devices that modulate and demodulate
signals


Multiplexers


Devices that allow several telephones or
computers to transmit data through a single
line


Frequency division multiplexing


Time
-
division multiplexing

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Modulation

Figure 6.9 Multiplexing

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Modulation

Figure 6.10 Frequency division

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Networks


LANs (Local Area Networks)


Networks within a building, or within a group
of adjacent buildings


WANs (Wide Area Networks)


Networks that cross organizational boundaries
or reach outside the company


Value
-
added networks (VANs)


Wireless communication


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Networks





Figure 6.11
Where
wireless LANs
are a good
choice

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Networks


Network Topology


Physical layout of the nodes in a network


Star


Ring


Bus


Tree

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Network Topology

Figure 6.12 Network topologies

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Protocols


Communication protocols


Rules governing the communication between
computers or between computers and other
computer
-
related devices


Network protocols


Rules governing a network of devices

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Protocols

Figure 6.13 Some communications software allows a user to establish
protocols: bit rate, parity, number of data bits, stop bits, and a
handshake procedure
.

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Protocols


LAN Protocols


Polling


Contention


Token passing



WAN Protocols


OSI (Open Systems Interconnection)


Standard protocol model


Seven layers

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Protocols

Figure 6.14 The seven layers of the OSI model

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Switching Techniques and
Transfer Modes


Circuit Switching


Message is communicated in its entirety from
the transmitting computer to the receiving
computer


Packet Switching


Message is divided into packets of bytes and
transmitted via several nodes



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The Changing Business
Environment


Cellular Phones


Teleconferencing


Voice Mail


Facsimile


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Ethical and Societal Issues

Telecommuting: Pros and Cons


Pros


Saves travel cost and time


Decreases pollution


May reduce unemployment.


Productivity higher among telecommuters


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Ethical and Societal Issues

Telecommuting: Pros and Cons


Cons


Employers tend to pressure
telecommuters to work harder than
workers in the office.


No office to foster new social ties and
camaraderie.


May negatively impact some segments
of the economy


Restaurants


Downtown business and industries