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Transcript
6
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:
6
 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.
2
Learning Objectives
6
 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.
3
Telecommunications in
Business
 Telecommunications
6
 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
4
What is Data
Communications?
 Data Communications
6
 Any transfer of data within a computer,
between a computer and another device, or
between two computers
 Two Basic Modes
 Parallel transmission
 Serial transmission
5
What is Data
Communications?
6
Figure 6.1 Parallel and serial transmission
6
Communication Direction
 Three Modes of Communication Between
Devices
6
 Simplex
 One-way in one direction
 Half-Duplex
 One-way in two directions
 Full-Duplex
 Two-way in two directions
7
Communication Direction
6
Figure 6.2 Simplex, half-duplex, and full-duplex
communication
8
Communication Direction
 Asynchronous Communication
6
 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
9
Communication Modes
6
Figure 6.3 The character D transmitted in asynchronous mode
10
Communication Modes
 Synchronous Communication
6
 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.
11
Communication Modes
6
Figure 6.4 Synchronous transmission
12
Channels and Media
 Communication Channel
6
 Physical medium through which data can
be communicated.
 Channel Capacity
 Narrow band
 Broadband
13
Channels and Media
6
Figure 6.5 Transmission speed measurement
unit
14
Channels and Media
 Media
6
 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
15
Channels and Media
6
Figure 6.6 Telecommunications transmission speeds of
different media
16
Channels and Media
 Twisted Pair
6
 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
17
Channels and Media
 Microwaves
6
 High-frequency, short radio-frequency
(RF) waves
 Terrestrial microwave
 Satellite microwave
 Optical Fiber
 Fiber-optic technology uses light instead of
electricity to transmit data.
18
Channels and Media
6
Figure 6.7 Characteristics of channel media
19
Modulation
 Analog vs. Digital
 Analog signals
 A continuous series of waves
6
 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
20
Modulation
6
Figure 6.8 Signal modulation
21
Modulation
 Amplitude Modulation (AM)
6
 Frequency Modulation (FM)
 Phase Modulation
22
Modulation
 Modems
6
 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
23
Modulation
6
Figure 6.9 Multiplexing
24
Modulation
6
Figure 6.10 Frequency division
25
Networks
 LANs (Local Area Networks)
6
 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
26
Networks
6
Figure 6.11
Where wireless
LANs are a good
choice
27
Networks
 Network Topology
 Physical layout of the nodes in a network
6
 Star
 Ring
 Bus
 Tree
28
Network Topology
6
Figure 6.12 Network topologies
29
Protocols
 Communication protocols
6
 Rules governing the communication
between computers or between computers
and other computer-related devices
 Network protocols
 Rules governing a network of devices
30
Protocols
6
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.
31
Protocols
 LAN Protocols
6
 Polling
 Contention
 Token passing
 WAN Protocols
 OSI (Open Systems Interconnection)
 Standard protocol model
 Seven layers
32
Protocols
6
Figure 6.14 The seven layers of the OSI
model
33
Switching Techniques and
Transfer Modes
 Circuit Switching
6
 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
34
A Variety of Services
6
Figure 6.15
Services offered by
telecommunications
firms
35
The Changing Business
Environment
 Cellular Phones
6
 Teleconferencing
 Voice Mail
 Facsimile
36
Ethical and Societal Issues
Telecommuting: Pros and Cons
 Pros
6
 Saves travel cost and time.
 Decreases pollution.
 May reduce unemployment.
 Productivity higher among telecommuters.
37
ETHICS AND SOCIETY
Telecommuting: Pros and Cons
 Cons
6
 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
38