Management Information Systems, 3 rd Edition Effy Oz 1 Chapter 6 Information Technology in Business: Telecommunications and Networks

Management Information Systems, 3rd EditionEffy Oz

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Chapter 6Information Technology in

Business: Telecommunications and

Networks


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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.


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Telecommunications in Business• Telecommunications

– Transmittal of data from one computer to another over a distance

• Telecommunications has brought four basic improvements to business process:– Better communication– Higher efficiency – Better distribution of data– Instant transactions


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Data Communications

• Data Communications

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


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Types of Data Communications

• Two Basic Modes– Parallel transmission

• Each byte is transmitted in its entirety

• Parallel port

– Serial transmission• Data are transmitted one bit at a time through a

single line

• Serial port


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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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Communication Direction

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


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Synchronization

• 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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Synchronization

• 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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Channels and Media

• Communication Channel– Physical medium through which data can be

communicated.

• Capacity– Speed at which data are 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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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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Modulation

– Analog vs. Digital • Analog signals

– A continuous series of waves

• Digital signals– A series of discrete bits


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Modulation

– 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

• Set-Up• Fas/Voice

• 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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Network Topology

• Virtual Private Networks (VPN)– Combination of public and private lines

• LAN is a private network (only provides access to members of an organization)


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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

• Usually referred to as Ethernet

– 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

• 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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A Variety of Services

• Integrated Services Data Networks (ISDN)

• Cable

• Digital Subscriber Line (DSL

• T1 and T3 Lines

• Satellite

• Fixed Wireless

• Gigabit Ethernet


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The Changing Business Environment

• Cellular phones

• Videoconferencing

• Voice Mail

• Facsimile

• Web-based Electronic Commerce


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Ethical and Societal IssuesTelecommuting: 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 IssuesTelecommuting: 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

Documents

Management Information Systems, 3 rd Edition Effy Oz 1 Chapter 6 Information Technology in Business: Telecommunications and Networks