Ch07
-
Upload
roxanne2006 -
Category
Education
-
view
1.436 -
download
0
description
Transcript of Ch07
Principles of Information Systems
Eighth Edition
Chapter 6
Telecommunications and Networks
Principles of Information Systems, Eighth Edition 2
Principles and Learning Objectives
• Effective communications are essential to organizational success– Define the terms communications and
telecommunications and describe the components of a telecommunications system
Principles of Information Systems, Eighth Edition 3
Principles and Learning Objectives (continued)
• Communications technology lets more people send and receive all forms of information over greater distances at a faster rate than ever before– Identify two broad categories of communications
media and their associated characteristics– Identify several communications hardware devices
and discuss their function– Name three types of telecommunications carriers
and discuss the services they provide– Describe many of the benefits associated with a
telecommunications network
Principles of Information Systems, Eighth Edition 4
Principles and Learning Objectives (continued)
• Communications technology lets more people send and receive all forms of information over greater distances at a faster rate than ever before (continued)– Define the term communications protocols and
identify several common ones– Name three distributed processing alternatives and
discuss their basic features– List and describe several telecommunications
applications that organizations benefit from today
Principles of Information Systems, Eighth Edition 5
Why Learn About Telecommunications and Networks?
• Need to access data wherever it resides– Fast, reliable communications– Exchange messages– Upload/download data and software– Route business transactions– Connect to remote databases– Send output to printers
Principles of Information Systems, Eighth Edition 6
An Overview Of Telecommunications
• Telecommunications: electronic transmission of signals for communications– Telephone, radio, and television
• Communications can be synchronous or asynchronous– Synchronous communications: receiver gets
message instantaneously– Asynchronous communications: receiver gets
message after some delay
Principles of Information Systems, Eighth Edition 7
An Overview Of Telecommunications (continued)
Figure 6.1: Elements of a Telecommunications System
Principles of Information Systems, Eighth Edition 8
Basic Communications Channel Characteristics
• Communication channels can be classified as:– Simplex channel: transmits data in only one
direction– Half-duplex channel: transmits data in either
direction, but not simultaneously– Full-duplex channel: permits data transmission in
both directions at the same time
Principles of Information Systems, Eighth Edition 9
Channel Bandwidth
• Channel bandwidth: rate at which data is exchanged over a communications channel– Usually measured in bits per second (bps)
• Broadband communications: telecommunications system in which a very high rate of data exchange is possible
• Narrowband communications: telecommunications system that supports a much lower rate of data exchange than broadband
Principles of Information Systems, Eighth Edition 10
Communications Media
• Guided transmission media: communications signals guided along a solid medium
• Wireless media: communications signal broadcast over airwaves as a form of electromagnetic radiation
Principles of Information Systems, Eighth Edition 11
Guided Transmission Media Types
Table 6.1: Guided Transmission Media Types
Principles of Information Systems, Eighth Edition 12
Guided Transmission Media Types (continued)
Table 6.2: Wireless Technologies
Principles of Information Systems, Eighth Edition 13
Telecommunications Hardware
• Typical telephone line only accommodates an analog signal (continuous, curving signal)
• Computers generate a digital signal representing bits
• Modem: device that translates data from digital to analog and analog to digital
Principles of Information Systems, Eighth Edition 14
Telecommunications Hardware (continued)
Figure 6.6: How a Modem Works
Principles of Information Systems, Eighth Edition 15
Telecommunications Hardware (continued)
• Multiplexer: device that encodes data from two or more data sources onto a single communications channel– Reduces number of communications channels
needed– Lowers telecommunications costs
• Front-end processors: special-purpose computers that manage communications serving hundreds or even thousands of users
Principles of Information Systems, Eighth Edition 16
Services
• Telecommunications carriers organize communications channels, networks, hardware, software, people, and business procedures to provide valuable communications services
Principles of Information Systems, Eighth Edition 17
Digital Subscriber Line (DSL)
• Telecommunications technology that delivers high-bandwidth information to homes and small businesses over ordinary copper telephone wires
• Asymmetric DSL (ADSL): download speed is three to four times faster than upload speed
• Symmetric DSL (SDSL): speed of receiving and sending data is the same– Does not allow you to use the phone at the same
time
Principles of Information Systems, Eighth Edition 18
Digital Subscriber Line (DSL) (continued)
Figure 6.8: Digital Subscriber Line (DSL)
Principles of Information Systems, Eighth Edition 19
Wireless Telecommunications
• All major long-distance carriers offer wireless telecommunications services – Phone calls or Internet access
• Wireless data communications will be broadly adopted when providers can offer business users enough bandwidth and connectivity so that they use wireless as their sole connection
Principles of Information Systems, Eighth Edition 20
Networks and Distributed Processing
• Computer network: communications media, devices, and software needed to connect two or more computer systems and/or devices
• Network nodes: computers and devices on the networks
Principles of Information Systems, Eighth Edition 21
Network Types
• Personal area network (PAN)
• Local area network (LAN)
• Metropolitan area network (MAN)
• Wide area network (WAN)
• International networks
• Mesh networking
Principles of Information Systems, Eighth Edition 22
Network Types (continued)
Figure 6.11: Partial Mesh Network
Principles of Information Systems, Eighth Edition 23
Distributed Processing
• Centralized processing: all processing occurs at a single location or facility
• Decentralized processing: processing devices are placed at various remote locations
• Distributed processing: computers are placed at remote locations but are connected to each other via a network
Principles of Information Systems, Eighth Edition 24
Client/Server Systems
• Client/server: multiple computer platforms are dedicated to special functions such as database management, printing, communications, and program execution– Each server is accessible by all computers on the
network– A client is any computer that sends messages
requesting services from servers on the network
Principles of Information Systems, Eighth Edition 25
Client/Server Systems (continued)
Figure 6.13: Client/Server Connection
Principles of Information Systems, Eighth Edition 26
Communications Software and Protocols
• Communications protocol: set of rules that governs the exchange of information over a communications channel
• ATM
• Frame relay
• IEEE 802.3 (Ethernet)
• T-carrier system
Principles of Information Systems, Eighth Edition 27
Communications Software and Protocols (continued)
Table 6.4: Common Telecommunications Protocols
Principles of Information Systems, Eighth Edition 28
Wireless Communications Protocols
• Wi-Fi
• WiMAX
• Smart antenna technology
• Ultra Wideband (UWB)
• 3G wireless communication
• 4G wireless communications
Principles of Information Systems, Eighth Edition 29
Wireless Communications Protocols (continued)
Table 6.14: Wi-Fi Network
Principles of Information Systems, Eighth Edition 30
Wireless Communications Protocols (continued)
• Switch: uses physical device address in each incoming message to forward message to another device on the same network
• Bridge: connects one LAN to another LAN that uses the same telecommunications protocol
• Router: forwards data packets across two or more distinct networks toward their destinations through routing
• Gateway: serves as an entrance to another network
Principles of Information Systems, Eighth Edition 31
Communications Software
• Network operating system (NOS): systems software that controls computer systems and devices on a network and allows them to communicate with each other
• Network-management software – Monitors the use of individual computers and shared
hardware – Scans for viruses – Ensures compliance with software licenses
Principles of Information Systems, Eighth Edition 32
Telecommunications and Network Applications
• Telecommunications and networks are a vital part of today’s information systems
• In some industries, telecommunications is virtually a requirement for doing business
Principles of Information Systems, Eighth Edition 33
Linking Personal Computers to Mainframes and Networks
• Personal computers can be connected to mainframe computers so that data can be downloaded or uploaded– Example: user can download a file from a database
to a personal computer
• Unattended systems: communications software programs that instruct the computer to connect to another computer on the network, download or send information, and then disconnect from the telecommunications line
Principles of Information Systems, Eighth Edition 34
Voice Mail
• Users can send, receive, and store verbal messages for and from other people around the world
• Call management systems can be linked to corporate e-mail and instant messaging systems
Principles of Information Systems, Eighth Edition 35
Home and Small Business Networks
• Simple networks can be used to share printers or an Internet connection, access files on different machines, etc.
• Wireless network – 802.11n access point– Combined router, firewall, Ethernet hub, and
wireless hub
• Configure computers to share printers and files
Principles of Information Systems, Eighth Edition 36
Electronic Document Distribution
• Send and receive documents in a digital form without printing them (although printing is possible)– Much faster – Saves paper– Saves document storage space
Principles of Information Systems, Eighth Edition 37
Call Centers
• Call center: physical location where an organization handles customer and other telephone calls – Usually with some computer automation
• Automatic call distributor (ACD): telephone facility that manages incoming calls– Handles calls based on the called number and an
associated database of instructions
• National Do Not Call Registry
• Offshore call centers
Principles of Information Systems, Eighth Edition 38
Telecommuting and Virtual Workers and Workgroups
• Telecommuting: employees work away from the office using computing devices and networks– More effective workers– Saves money on office and parking space and office
equipment– Reduces traffic congestion and air pollution
• Some types of jobs are better suited for telecommuting than others
• Telecommuters must work independently, manage time well, and balance work and home life
Principles of Information Systems, Eighth Edition 39
Videoconferencing
• Enables people to hold a conference by combining voice, video, and audio transmission– Reduces travel expenses and time– Increases managerial effectiveness through faster
response to problems, access to more people, and less duplication of effort in multiple sites
• Systems usually combine video and phone call capabilities with data or document conferencing
Principles of Information Systems, Eighth Edition 40
Electronic Data Interchange
• Intercompany, application-to-application communication of data in a standard format– Permits recipient to perform a standard business
transaction, such as processing purchase orders– Follows standards and procedures that can process
output from one system directly as input to other systems without human intervention
Principles of Information Systems, Eighth Edition 41
Electronic Data Interchange (continued)
Table 6.17: Two Approaches to Electronic Data Interchange
Principles of Information Systems, Eighth Edition 42
Public Network Services
• Give personal computer users access to vast databases, the Internet, and other services– Usually an initial fee plus usage fees– Fees are based on services used; can range from
under $15 to over $500 per month
• Providers of public network services include Microsoft, America Online, and Prodigy
Principles of Information Systems, Eighth Edition 43
Electronic Funds Transfer
• Electronic funds transfer (EFT)– Transfers money from one bank account directly to
another without the use of paper money• Wire transfer
– Fast, reliable means to move funds from one account to another using one of three major wire-transfer networks
• Automated clearing house (ACH)– Secure private network connecting all U.S. financial
institutions to each other through the Federal Reserve Board or other ACH operators
Principles of Information Systems, Eighth Edition 44
Distance Learning
• Use of telecommunications to extend the classroom– Instructors create course home pages on the
Internet– Students access the course syllabus and instructor
notes on the Web page– Student e-mail mailing lists allow students and the
instructor to e-mail one another– Chat groups allow students to form “virtual teams”
Principles of Information Systems, Eighth Edition 45
Team Collaboration Systems
• Microsoft Office Groove: example of software designed to enable collaboration and communication within small teams– Allows you to set up shared workspaces among
employees and others outside your organization
Principles of Information Systems, Eighth Edition 46
Specialized Systems and Services
• Increased interest in specialized and regional information services
• Electronic bulletin board: message center that displays messages in electronic form– Regional, national, and international bulletin boards
• Global positioning systems (GPSs) provide specialized telecommunications services
• Virtual workers: conduct business at any time and place
Principles of Information Systems, Eighth Edition 47
Summary
• Telecommunications: electronic transmission of signals for communications, by such means as telephone, radio, and television
• Guided transmission media types: twisted-pair wire, coaxial cable, fiber-optic cable, and broadband over power lines
• Wireless transmission types: microwave, radio, and infrared
• Computer network: communications media, devices, and software needed to connect two or more computer systems and/or devices
Principles of Information Systems, Eighth Edition 48
Summary (continued)
• Network types: personal area network (PAN), local area network (LAN), metropolitan area network (MAN), wide area network (WAN), international networks, and mesh networking
• Client/server systems: multiple computer platforms dedicated to special functions such as database management, printing, communications, and program execution
• Communications protocol: set of rules that governs the exchange of information over a communications channel
Principles of Information Systems, Eighth Edition 49
Summary (continued)
• Examples of telecommunications and network applications– Linking personal computers to mainframes and
networks, voice mail, home and small business networks, electronic document distribution, call centers, telecommuting, videoconferencing, electronic data interchange, public network services, electronic funds transfer, distance learning, and team collaboration systems