Technology Guide 4Telecommunications
andthe Internet
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IT for ManagementProf. Efraim Turban
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Telecommunication Concepts
• Telecommunication– long-distance communication through the
use of common carriers, including telephone, television, and radio.
• Data Communications– Electronic collection, exchange, and
processing of data or information, including text, pictures, voice, and other information that is digitally coded and intelligible to a variety of electronic machines
IT for ManagementProf. Efraim Turban
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Telecommunication System
HostComputer
HostComputer
PC orTerminal
PC orTerminal
MultiplexorMultiplexor
ModemModem
HostComputer
HostComputer
PC orTerminal
PC orTerminal
MultiplexorMultiplexor
ModemModem
Hardware
Front endprocessor
Receiver
Telecommunicationmedia
(channels)
IT for ManagementProf. Efraim Turban
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Electronic Signals
• Analog Signals– continuous waves that “carry” information
by altering the characteristics of the waves– amplitude and frequency
• Digital Signals– discrete on-off pulses that convey
information in terms of 1s and 0s, just like the central processing unit in computers
IT for ManagementProf. Efraim Turban
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Database andDatabase Management Systems• Database
– an organized logical grouping of related files– no data redundancy, data isolation, and data
inconsistency
• Database Management Systems (DBMS)– a program that provides access to a database– permits an organization to centralize data,
manage them efficiently, and provide access to the stored data by application programs
IT for ManagementProf. Efraim Turban
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Communication Processors
• Modem– Performs modulation and
demodulation
– Modulation convert information from digital to analog
– Demodulation convert information form analog to digital
IT for ManagementProf. Efraim Turban
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Communication Processors
• Multiplexor– An electronic device that allows a single
communications channel to carry data transmissions simultaneously from many sources
• Front-end Processor– A specialized computer that managers
all routing communications with peripheral devices
IT for ManagementProf. Efraim Turban
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Communications Media (Channels)
• Cable Media– Twisted-pair wire consists of strands of copper wire
twisted in pairs
– Coaxial cable consists of insulated copper wire, and is much less susceptible to electrical interference and can carry much more data than twisted-pair wire
– Fiber Optics consists of thousands of very thin filaments of glass fibers
– Photonics generates and harnesses light and other forms of radiant energy whose quantum unit
IT for ManagementProf. Efraim Turban
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Communications Media (Channels)
• Wireless Media– Microwave– Satellite
• geostationary earth orbit (GEO); medium earth orbit (MEO); and low earth orbit (LEO)
– Global Positioning Systems– Radio– Infrared
IT for ManagementProf. Efraim Turban
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Communications Media (Channels)
• Wireless Media– Cellular Radio Technology
• Wireless Application Protocol (WAP); Wireless Markup Language (WML)
– Mobile Computer
– Personal Communication service
– Personal Digital Assistants
IT for ManagementProf. Efraim Turban
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Characteristics of Communication Media
• Transmission Speed– bandwidth : the range of frequencies available
in any communications channel– bit per second (bps) : the unit of measurement– channel capacity : narrowband, voiceband, and
broadband– baud rate : the amount of data that can be
transmitted through a communications channel
• Optical Networking– dense wave division multiplexing (DWDM)
IT for ManagementProf. Efraim Turban
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Transmission Direction
• Simplex Data Transmission– uses only one direction only
• Half-duplex Transmission– uses only one circuit, but it is used in
both directions
• Full-duplex Transmission– uses two circuit for communications –
one for each direction simultaneously
IT for ManagementProf. Efraim Turban
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Transmission Mode
• Asynchronous Transmission– only one character is transmitted or received
at a time– inherently inefficient
• Synchronous Transmission– a group of characters is sent over a
communications link in a continuous bit stream while data transfer is controlled by a timing signal initiated by the sending device
IT for ManagementProf. Efraim Turban
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Transmission Accuracy
• Telephone line cables may be mishandled by repair personnel, accidentally cut by construction workers, or subjected to power surges while data are being transmitted.
• Accuracy controls consist of bits called parity bits that are like check sums aded to characters and/or blocks of characters at the sending end of the line.
IT for ManagementProf. Efraim Turban
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Protocols
• Protocol is a set of rules and procedures governing transmission across a network
• Transmission Control Protocol/Internet Protocol (TCP/IP) is a file transfer protocol that can send large files of information n across sometimes unreliable networks with assurance that he data will arrive in uncorrupted form
IT for ManagementProf. Efraim Turban
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Communication Standards• Network Standards
– physical layer, data link layer, network layer, transport layer, session layer, presentation layer, and application layer
– System Network architecture (SNA) standard
• Transmission Standards– fiber distributed data interface (FDDI), asynchronous
transfer mode (ATM), switch hub technologies, and Integrated services digital network (ISDN)
• Software Standards– Operating systems, graphical user interface standard,
software application standards
IT for ManagementProf. Efraim Turban
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Interfaces
• Parallel Data Transfer– most often used for local communication, employs
a communications interface with a series of dedicated wires, each serving one purpose
– both data and control signals are transmitted simultaneously
• Serial Data Transfer– most often used for long-distance communications,
is bit by bit rather than many bits in parallel
IT for ManagementProf. Efraim Turban
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Network Topology
• Bus Network– nodes are arranged along a single length of
twisted-pair wire, coaxial cable, or fiber optic cable that can be extended at he ends
• Rink Network– nodes are arranged along the transmission path
so that a signal passes through one station at a time before returning to its originating node
• Star Network– a central node that connects to each of the other
nodes by a single, point-to-point link
IT for ManagementProf. Efraim Turban
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Local Area Networks (LAN)
• LAN connects two or more communicating devices within a short distance– Gateway is a communications processor that
can connect dissimilar net works by translating for one set of protocols to another
– Bridge connects two networks of the same type– Router routes messages through several
connected LANs or to a WAN
• Private Branch Exchange (PBX)
IT for ManagementProf. Efraim Turban
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Wide Area Networks (WANs)
• Value-Added Networks (VAN)– private, multipath, data-only, third-party-
managed networks that can provide economies in the cost of service and network management
• Frame Relay– a shared network service that packages data into
“frames” that are similar to packets
• Virtual Private Network (VPN)– a set of hardware and software that provides a
gateway between a corporate LAN and the internet
IT for ManagementProf. Efraim Turban
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Network Processing
• Point-to-Point Connection– two devices on a network are
directly connected
• Peer-to-Peer Connection– two devices have the same relative
standing, as with two microcomputers
IT for ManagementProf. Efraim Turban
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Client/Server Architecture
• Presentation Component– the application interface or how the
application appears to the user
• Applications Logic– created by the business rules of the
application
• Data Management Component – consists of the storage and management
of the data needed by the application
IT for ManagementProf. Efraim Turban
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Types ofClient/Server Architecture
• Distributed Presentation
• Remote Presentation
• Distributed Function
• Remote Data Management
• Distributed Data Management
IT for ManagementProf. Efraim Turban
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Peer-to-Peer Architecture
• Network information is stored on a centralized file server and made available to ma clients, the Information stored across peer-to-peer networks is uniquely decentralized.
• Popular peer-to-peer network operating systems include Microsoft’s Windows 95 and 98, Windows NT, Artisoft’s LANtastic, and Netware Lite.
IT for ManagementProf. Efraim Turban
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Open Systems andEnterprise Networking
• Connectivity– the ability of the various computer resources to communicate
with each other through network devices without human intervention
• Portability– the ability to move applications, data, and even people form
one system to another with minimal adjustments• Interoperability
– the ability of systems to work together by sharing applications, data, nd computer resources.
• Scalability– the ability to run applications unchanged on any open system
where the hardware can range form a laptop PC to a supper computer
IT for ManagementProf. Efraim Turban
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Open Systems andEnterprise Networking
• Embedded LANs– open systems and connectivity have
enabled networks to completely span organization
– Most firms have multiple LANs and may have multiple WANs, which are interconnected to form an enterprisewide network
IT for ManagementProf. Efraim Turban
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Internet
• Basic Characteristics and Capabilities– Accessing the Internet
• access an internet-connected file server on your organization’s LAN
• log into the Internet from your home• wireless connections
– TV as a channel to the Internet• a special connection device, and a
telephone connection
IT for ManagementProf. Efraim Turban
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Internet
• The TCP/IP Protocol– procedures and rules for transferring data
across the internet• Internet Resources
– access libraries and conduct research– access to large databases– access to online magazines
• Wide Area Information Servers (WAIS)– an Internet directory designed to help end users
find and retrieve information over the networks by providing efficient search methods
IT for ManagementProf. Efraim Turban
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Internet
• The World Wide Web– a vast connection of interconnected pages of
information that are stored on computers around the world that are connected to the internet
• Bowser– a set of standards for storing, retrieving,and
manipulating information• Hyperlinks
– links to internal or external documents• Web Site : a computer network• Web Page : a document
IT for ManagementProf. Efraim Turban
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Internet
• Creating Web Documents– HyperText Markup Language (HTML)– Java
• Search Engines– enable you to locate information by using
key words in the same way that you would search online library resources
• Internet Addresses– uniform resource locator (URL)– hypertext transfer protocol (HTP)
IT for ManagementProf. Efraim Turban
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Internet
• Gopher– a “burrowing tool” that provides access to a
wide range of textual information available on the Internet
• Downloading Software and Files– cheapware, freeware, and shareware– file transfer protocol (FTP)
• Electronic Mall (e-mall)– allows multiple-access communication
delivered exclusively on a computer network
IT for ManagementProf. Efraim Turban
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Internet
• Chat Programs– allow you to send messages to people at the same time
• Newsgroup– organized in a directory and are divided into
categories and subcategories• Mailing Lists
– subscribe : add e-mail name and address– unsubscribe : remove the e-mail name and address
• Electronic Bulletin Boards– allow people leave messages for other people and
receive massive amounts of information• Portals
– a Web site designed to offer Internet services
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IT for ManagementProf. Efraim Turban
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