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Chapter 6 Information Technology in Business: Telecommunications and Networks. Learning Objectives. When you finish this chapter, you will: Recognize why successful managers must be familiar with telecommunications concepts and terminology.
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Chapter 6Information Technology in Business: Telecommunications and Networks
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.
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.
Telecommunications in Business • Telecommunications • 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
What is Data Communications? • Data Communications • Any transfer of data within a computer, between a computer and another device, or between two computers • Two Basic Modes • Parallel transmission • Serial transmission
Figure 6.1 Parallel and serial transmission What is Data Communications?
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
Figure 6.2 Simplex, half-duplex, and full-duplex communication Communication Direction
Communication Direction • 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
Figure 6.3 The character D transmitted in asynchronous mode Communication Modes
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.
Figure 6.4 Synchronous transmission Communication Modes
Channels and Media • Communication Channel • Physical medium through which data can be communicated. • Channel Capacity • Narrow band • Broadband
Figure 6.5 Transmission speed measurement unit Channels and Media
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
Figure 6.6 Telecommunications transmission speeds of different media Channels and Media
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
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.
Figure 6.7 Characteristics of channel media Channels and Media
Modulation • Analog vs. Digital • Analog signals • A continuous series of waves • 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
Figure 6.8 Signal modulation Modulation
Modulation • Amplitude Modulation (AM) • Frequency Modulation (FM) • Phase Modulation
Modulation • Modems • 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
Figure 6.9 Multiplexing Modulation
Figure 6.10 Frequency division Modulation
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
Networks • Network Topology • Physical layout of the nodes in a network • Star • Ring • Bus • Tree
Figure 6.12 Network topologies Network Topology
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
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. Protocols
Protocols • LAN Protocols • Polling • Contention • Token passing • WAN Protocols • OSI (Open Systems Interconnection) • Standard protocol model • Seven layers
Switching Techniques and Transfer Modes • 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
A Variety of Services Figure 6.15 Services offered by telecommunications firms
The Changing Business Environment • Cellular Phones • Teleconferencing • Voice Mail • Facsimile
Ethical and Societal IssuesTelecommuting: Pros and Cons • Pros • Saves travel cost and time. • Decreases pollution. • May reduce unemployment. • Productivity higher among telecommuters.
ETHICS AND SOCIETYTelecommuting: 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