Transcript Management Information Systems

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Chapter 6
Information Technology
in Business:
Telecommunications and
Networks
Management Information Systems, Second Edition
Effy Oz
Learning Objectives
 When you finish this chapter, you will:
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 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.
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Learning Objectives
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 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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Telecommunications in
Business
 Telecommunications
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 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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What is Data
Communications?
 Data Communications
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 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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What is Data
Communications?
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Figure 6.1 Parallel and serial transmission
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Communication Direction
 Three Modes of Communication Between
Devices
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 Simplex
 One-way in one direction
 Half-Duplex
 One-way in two directions
 Full-Duplex
 Two-way in two directions
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Communication Direction
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Figure 6.2 Simplex, half-duplex, and full-duplex
communication
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Communication Direction
 Asynchronous Communication
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 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
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Figure 6.3 The character D transmitted in asynchronous mode
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Communication Modes
 Synchronous Communication
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 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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Communication Modes
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Figure 6.4 Synchronous transmission
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Channels and Media
 Communication Channel
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 Physical medium through which data can
be communicated.
 Channel Capacity
 Narrow band
 Broadband
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Channels and Media
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Figure 6.5 Transmission speed measurement
unit
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Channels and Media
 Media
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 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.
 Baud
 Repeater
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Channels and Media
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Figure 6.6 Telecommunications transmission speeds of
different media
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Channels and Media
 Twisted Pair
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 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
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 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
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Figure 6.7 Characteristics of channel media
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Modulation
 Analog vs. Digital
 Analog signals
 A continuous series of waves
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 Digital signals
 A series of discrete bits
 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
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Figure 6.8 Signal modulation
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Modulation
 Amplitude Modulation (AM)
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 Frequency Modulation (FM)
 Phase Modulation
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Modulation
 Modems
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 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
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Figure 6.9 Multiplexing
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Modulation
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Figure 6.10 Frequency division
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Networks
 LANs (Local Area Networks)
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 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
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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
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 Star
 Ring
 Bus
 Tree
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Network Topology
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Figure 6.12 Network topologies
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Protocols
 Communication protocols
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 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
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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
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 Polling
 Contention
 Token passing
 WAN Protocols
 OSI (Open Systems Interconnection)
 Standard protocol model
 Seven layers
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Protocols
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Figure 6.14 The seven layers of the OSI
model
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Switching Techniques and
Transfer Modes
 Circuit Switching
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 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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A Variety of Services
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Figure 6.15
Services offered by
telecommunications
firms
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The Changing Business
Environment
 Cellular Phones
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 Teleconferencing
 Voice Mail
 Facsimile
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Ethical and Societal Issues
Telecommuting: Pros and Cons
 Pros
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 Saves travel cost and time.
 Decreases pollution.
 May reduce unemployment.
 Productivity higher among telecommuters.
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ETHICS AND SOCIETY
Telecommuting: Pros and Cons
 Cons
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 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
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