Transcript Management Information Systems

Information Technology in
Business:
Telecommunications,
Networks and Internet Basics
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.
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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.
– Understand the historical development of the Internet
– Understand the main structural components of the
Internet
– Understand how HTML, HTTP, browsers and servers
work together to form the WWW
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Telecommunications in
Business
• Telecommunications
– Any form of long distance communication,
including telephone, television and radio
• Telecommunications has improved
business in three main ways:
– Better communication
– Higher efficiency
– Better distributionMISof221data
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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
• Integration
– Business are increasingly integrated in their use of
computers, telephony, video and data networks
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What is a Telecommunications
System?
• Compatible hardware and software used to
communicate information from one place to
another
– Will include voice, text, graphics, documents and
video
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A Generalized
Telecommunications System
• Hardware (Host computer, front end
communication processor, modem, multiplexor)
• Communications media (Cable or wireless)
• Communications software
• Data communications providers
• Communications protocols
• Communications applications (EDI,
videoconferencing, EFT, etc.)
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Electronic Signals
• Analog
– Information imbedded in the changing
characteristics of the wave
• Amplitude or frequency based
• Digital
– Information imbedded as 1 or 0, on or off
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Modulation
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Figure 6.8 Signal modulation
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Modulation
• Amplitude Modulation (AM)
• Frequency Modulation (FM)
• Phase Modulation
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Multiplexing
Figure 6.9 Multiplexing
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Communications Devices
• Modems
– Devices that modulate and demodulate signals,
converting from analog to digital and digital to
analog
• Multiplexers
– Devices that allow several telephones or computers
to transmit data through a single line
• Frequency-division multiplexing
• Time-division multiplexing
• Front End Processors
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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
• 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.
• Baud
• Repeater
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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.
• Cellular and Wireless
– Radio frequency technologies
– Fixed or mobile
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Channels and Media
Figure 6.5 Transmission speed measurement unit
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Channels and Media
Figure 6.6 Telecommunications transmission speeds of different media
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Channels and Media
Figure 6.7 Characteristics of channel media
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A Variety of Services
Figure 6.15
Services offered by
telecommunications
firms
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What is Data
Communications?
Figure 6.1 Parallel and serial transmission
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Communication Direction
• Three Modes of Communication
Between Devices
– Simplex
• One direction only
– Half-Duplex
• Both directions, but only one at a time
– Full-Duplex
• Simultaneous in both directions
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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
• Does not need sophisticated and expensive timing
hardware
– Disadvantage
• Overhead, time spent transmitting bits that are not
a part of the primary data
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Communication Modes
Figure 6.3 The character D transmitted in asynchronous mode
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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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Communication Modes
Figure 6.4 Synchronous transmission
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Protocols
• Definition
– Rules and procedures governing transmission across
a network
• Line access
• Collision avoidance
• TCP/IP
–
–
–
–
Standard protocol of the Internet and intranets
Transmission Control Protocol/Internet Protocol
Designed for sending large files across unreliable networks
Utilizes packets of information
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OSI Standard
• Seven Layer Model
– Governs peer-to-peer communication
between software at each layer
– From physical layer (how bits are transmitted
over a channel)
– To application layer (file transfer, security, etc)
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Open Systems Interconnect Model
Figure 6.14 The seven layers of the OSI model
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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 across significant distances, either within a
single organization or spanning multiple organizations
• Value-added networks (VANs)
• Wireless communication
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Network Topology
Figure 6.12 Network topologies
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Networks Devices
• Bridge
– Connects two networks at the data link layer
• Router
– Connects two networks at network layer
– Provides intelligent routing, some network
management functions and security
• Gateways
– Connect networks using different protocols
• Switches
– Incorporate features of bridges and gateways
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Other Standards (or lack
thereof)
• Operating Systems
– No standard exists
• Graphical User Interface
– X Windows
• Software Applications
– No standard for programming language,
DBMS, etc.
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Client/Server Computing
• Enabled by proliferation of powerful
desktop computers and decentralized
servers
• Principle
– Processing functions divided between to
separate, distinct computers
– One requests services of a server (the
client)
– One delivers a service upon request (the
server)
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Example of Client/Server
Computing
• Email
– Email client (Outlook) sends request to
POP server for messages
– POP Server receives and validates
request to download email
– Client processes data received (formats,
displays, stores messages)
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Example of Client/Server
Computing
• Database Transaction
– Client program running on PC sends
query to DBMS running on central server
– DBMS on server parses and executes
the query
– DBMS assembles resulting data (or
status result) and sends it to client
– Client receives data and processes it
(displays it, sends message to user, etc)
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Benefits of Client/Server
Computing
• Potential to reduce cost
– By offloading computing cycles to
cheaper and underutilized desktop PC
• Improved performance
– Has enabled high-performing graphical
user interfaces
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