Information Technology in Business: Telecommunications, Networks and Internet Basics.

Information Technology in Business:

Telecommunications, Networks and Internet Basics

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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 distribution of data

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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

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 6.15Services offered by telecommunicationsfirms

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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