321450Management of Information Technology321450321450Management Management of of Information Information TechnologyTechnology
Chapter 8Chapter 8
Telecommunication Technology
AsstAsst.. ProfProf.. WichaiWichai BunchuaBunchuaEE--mail mail :: wichaiwichai@@buubuu..acac..thth
httphttp://://www.informaticswww.informatics..buubuu..acac..thth//~~wichaiwichai
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An Overview Of TelecommunicationsAn Overview Of An Overview Of TelecommunicationsTelecommunications
� Telecommunications� Electronic transmission of signals for
communications� Telecommunications medium
� Any material substance that carries an electronic signal to support communications between a sending and receiving device
� Telecommunications protocol � Defines set of rules that governs the exchange of
information over a communications medium
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An Overview Of Telecommunications (continued)
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An Overview Of Telecommunications (continued)An Overview Of An Overview Of Telecommunications (continued)Telecommunications (continued)
� Synchronous communications� Receiver gets message instantaneously
� Asynchronous communications� Receiver gets message after some delay
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Basic Telecommunications Channel CharacteristicsBasic Telecommunications Channel Basic Telecommunications Channel CharacteristicsCharacteristics
� 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
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Basic Telecommunications Channel Characteristics (continued)Basic Telecommunications Channel Basic Telecommunications Channel Characteristics (continued)Characteristics (continued)
� Channel bandwidth
� Rate at which data is exchanged
� Telecommunications media
� Categories: guided transmission media and wireless
� Guided transmission media types
� Available in many types
� Twisted-pair wire
� Classified by category: Category 1, 2, 3, 4, 5, 5E, and 6
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Guided transmission media types
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Basic Telecommunications Channel Characteristics (continued)Basic Telecommunications Channel Basic Telecommunications Channel Characteristics (continued)Characteristics (continued)
� Coaxial cable� Offers cleaner and crisper data transmission (less
noise) than twisted-pair wire� Fiber-optic cable
� Transmits signals with light beams� Broadband over power lines
� Potential problem: transmitting data over unshielded power lines can interfere with both amateur (ham) radio broadcasts and police and fire radios
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Basic Telecommunications Channel Characteristics (continued)Basic Telecommunications Channel Basic Telecommunications Channel Characteristics (continued)Characteristics (continued)
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Basic Telecommunications Channel Characteristics (continued)Basic Telecommunications Channel Basic Telecommunications Channel Characteristics (continued)Characteristics (continued)
� Wireless communications options
� Wireless transmission involves the broadcast of communications in one of three frequency ranges
� Radio, microwave, or infrared frequencies
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Frequency Ranges Used for Frequency Ranges Used for Wireless CommunicationsWireless Communications
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Short Range Wireless OptionsShort Range Wireless OptionsShort Range Wireless Options
� Near Field Communication (NFC)� Short-range wireless connectivity technology
designed for cell phones and credit cards � Bluetooth
� Wireless communications specification that describes how cell phones, computers, personal digital assistants, etc., can be interconnected
� Ultra wideband (UWB)� Transmits large amounts of digital data over short
distances of up to 30 feet
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Short Range Wireless Options (continued)Short Range Wireless Options Short Range Wireless Options (continued)(continued)
� Infrared transmission� Sends signals at a frequency of 300 GHz
and above
� Zigbee� Form of wireless communications
frequently used in security systems and heating and cooling control systems
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Medium Range Wireless OptionsMedium Range Wireless OptionsMedium Range Wireless Options
� Wi-Fi � Wireless telecommunications technology brand
owned by the Wi-Fi Alliance� Wireless access point
� Consists of a transmitter with an antenna, receives the signal, and decodes it
� Wi-Fi access points � Have maximum range of about 300 feet outdoors
and 100 feet within a dry-walled building
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WiWi--Fi NetworkFi Network
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Wide Area Wireless Network OptionsWide Area Wireless Network OptionsWide Area Wireless Network Options
� Microwave transmission� High-frequency (300 MHz–300 GHz) signal sent
through the air� Common forms of satellite communications
� Geostationary satellite� Low earth orbit (LEO) satellite� Very small aperture terminal (VSAT)
� Wireless mesh� Uses multiple Wi-Fi access points to link a series
of interconnected local area networks
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Wide Area Wireless Network Options (continued)Wide Area Wireless Network Options Wide Area Wireless Network Options (continued)(continued)
� 3G wireless communications� Useful for business travelers, people on the go,
and people who need to get or stay connected� 4G wireless communications
� Will provide increased data transmission rates in the 20–40 Mbps range
� Worldwide Interoperability for Microwave Access (WiMAX)� Set of IEEE 802.16 wireless metropolitan area
network standards
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Future Wireless Communications DevelopmentsFuture Wireless Communications Future Wireless Communications DevelopmentsDevelopments
� Digital signal � Represents bits
� Analog signal� Variable signal, continuous in both time
and amplitude so that any small fluctuations in the signal are meaningful
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Networks and Distributed ProcessingNetworks and Distributed ProcessingNetworks and Distributed Processing
� Computer network� Consists of communications media,
devices, and software needed to connect two or more computer systems or devices
� Can transmit and receive information to improve organizational effectiveness and efficiency
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Network TypesNetwork TypesNetwork Types
� Personal area networks� Supports interconnection of information technology
within a range of about 33 feet� Local area networks
� Connects computer systems and devices within a small area (e.g., office or home)
� Metropolitan area networks� Connects users and their devices in a geographical
area that spans a campus or city� Wide area networks
� Ties together large geographic regions
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A Typical LANA Typical LAN
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A Wide Area Network
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Basic Processing AlternativesBasic Processing AlternativesBasic Processing Alternatives
� Centralized processing� All processing occurs in a single location or facility
� Decentralized processing� Processing devices are placed at various remote
locations� Distributed processing
� Processing devices are placed at remote locations but are connected to each other via a network
� File server systems� Users can share data through file server
computing
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File Server ConnectionsFile Server Connections
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Client/Server SystemsClient/Server SystemsClient/Server Systems
� Client/server architecture� Multiple computer platforms are dedicated to
special functions � Client
� Any computer that sends messages requesting services from the servers on the network
� Database server � Sends only the data that satisfies a specific query,
not the entire file
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Client/Server SystemsClient/Server SystemsClient/Server Systems
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The Client/Server NetworksThe ClientThe Client//Server Server NetworksNetworks
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Client/Server Systems (cont.)Client/Server Systems (cont.)Client/Server Systems (cont.)
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Telecommunications HardwareTelecommunications HardwareTelecommunications Hardware
� Modems
� Modulation/demodulation devices
� Multiplexers
� Combines data from multiple data sources into a single output signal that carries multiple channels
� Front-end processors
� Special-purpose computers that manage communications to and from a computer system
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Telecommunications Hardware (cont.)Telecommunications Hardware Telecommunications Hardware (cont.)(cont.)
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Telecommunications Hardware (continued)Telecommunications Hardware Telecommunications Hardware (continued)(continued)
� Private branch exchange (PBX)� Telephone switching exchange that serves a single
organization� Switches, bridges, routers, and gateways
� Switch: Uses the physical device address in each incoming message on the 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
� Gateway: Serves as an entrance to another network
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Telecommunications Hardware (cont.)Telecommunications Hardware Telecommunications Hardware (cont.)(cont.)
� Switch:
� Bridge:
� Router:
� Gateway:
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Telecommunications SoftwareTelecommunications SoftwareTelecommunications Software
� Network operating system (NOS)
� Systems software that controls the computer systems and devices on a network
� Network management software
� Protects software from being copied, modified, or downloaded illegally
� Performs error control to locate telecommunications errors and potential network problems
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Securing Data TransmissionSecuring Data TransmissionSecuring Data Transmission
� Encryption
� Converting an original message into a form that can only be understood by the intended receiver
� Key
� Variable value that is applied (using an algorithm) to a set of unencrypted text to produce encrypted text or to decrypt encrypted text
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The Encryption ProcessThe Encryption ProcessThe Encryption Process
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Securing Data Transmission (continued)Securing Data Transmission Securing Data Transmission (continued)(continued)
� Securing wireless networks
� Wired equivalent privacy (WEP)
� Used encryption based on 64-bit key, which has been upgraded to a 128-bit key
� Wi-Fi Protected Access (WPA)
� Security protocol that offers significantly improved protection over WEP
� War driving
� Involves hackers driving around with a laptop and antenna trying to detect insecure wireless access points
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Other Encryption MethodsOther Encryption MethodsOther Encryption Methods
� Data Encryption Standard (DES) � Early data encryption standard developed
in the 1970s that uses a 56-bit private key algorithm
� Advanced Encryption Standard (AES) � Extremely strong data encryption standard
based on a key size of 128 bits, 192 bits, or 256 bits
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Virtual Private Network (VPN)Virtual Private Network (VPN)Virtual Private Network (VPN)
� Private network that uses a public network (usually the Internet) to connect multiple remote locations
� Supports secure, encrypted connections between a company’s private network and remote users
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Telecommunications Services and Network ApplicationsTelecommunications Services and Telecommunications Services and Network ApplicationsNetwork Applications
� Cellular phone services� Operate using radio waves to provide two-
way communications
� Picocell� Miniature cellular base station designed to
serve a very small area such as part of a floor inside a building
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Cellular Phone Services Cellular Phone Services Cellular Phone Services
� Digital subscriber line (DSL) Service
� Telecommunications service that delivers high-speed Internet access
� Voice over Internet Protocol (VoIP) Services
� Enables voice conversations to be converted into packets of data that can be sent over a data network
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DSL DSL DSL
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VoIP Options VoIP Options VoIP Options
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Linking Personal Computers to Mainframes and NetworksLinking Personal Computers to Linking Personal Computers to Mainframes and NetworksMainframes and Networks
� Basic way that telecommunications connect users to information systems� Connecting personal computers to
mainframe computers so that data can be downloaded or uploaded
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Voice MailVoice MailVoice Mail
� Users can send, receive, and store verbal messages for and from other people around the world
� Reverse 911 service� Delivers emergency notifications to users in
a selected geographical area
� Voice-to-text services� Convert speech to text so that you can
manage voice mails more effectively
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Home and Small Business NetworksHome and Small Business NetworksHome and Small Business Networks
� DSL modem � Enables each computer in the network to
access the Internet
� Firewall� Filters the information coming from the
Internet into your network
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เครือขายดิจิตอลความเรว็สูง ADSLเครือขายดิจิตอลความเรว็สูงเครือขายดิจิตอลความเรว็สูง ADSLADSL
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Electronic Document DistributionElectronic Document DistributionElectronic Document Distribution
� Lets you send and receive documents in a digital form without printing them
� Much faster to distribute electronic documents via networks than to mail printed forms
� Viewing documents on screen instead of printing
� Saves paper and document storage space
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Call CentersCall CentersCall Centers
� Physical location where an organization handles customer and other telephone calls
� Used by:
� Customer service organizations
� Telemarketing companies
� Computer product help desks
� Charitable and political campaign organizations
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Telecommuting and Virtual Workers and WorkgroupsTelecommuting and Virtual Workers Telecommuting and Virtual Workers and Workgroupsand Workgroups
� Telecommuters
� Need to be strongly self-motivated, organized, focused on their tasks with minimal supervision
� Jobs unsuitable for telecommuting
� Those that require frequent face-to-face interaction, need much supervision, and have many short-term deadlines
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VideoconferencingVideoconferencingVideoconferencing
� 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
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Electronic Data InterchangeElectronic Data InterchangeElectronic Data Interchange
� Idea behind EDI
� Connecting corporate computers among organizations
� EDI
� Can link the computers of customers, manufacturers, and suppliers
� Eliminates the need for paper documents and substantially cuts down on costly errors
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Two Approaches to EDITwo Approaches to EDITwo Approaches to EDI
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Public Network ServicesPublic Network ServicesPublic 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
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Electronic Funds TransferElectronic Funds TransferElectronic Funds Transfer
� Transfers money from one bank account directly to another without the use of paper money
� Used for both credit and debit transfers
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Distance LearningDistance LearningDistance 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”
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Shared WorkspaceShared WorkspaceShared Workspace
� Common work area where:� Colleagues can share documents, issues,
models, schedules, spreadsheets, and all forms of information
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SummarySummarySummary
� Telecommunications and networks
� Creating profound changes in business because they remove the barriers of time and distance
� Communications
� Can be classified as synchronous or asynchronous
� Telecommunications media can physically connect data communications devices
� Guided transmission media and wireless media
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Summary (continued)Summary (continued)Summary (continued)
� Wireless communications solutions for very short distances include: � Near field communications, Bluetooth, ultra
wideband, infrared transmission, and Zigbee� Transborder data flow
� Electronic flow of data across international and global boundaries
� Client/server system � Network that connects a user’s computer (a client)
to one or more host computers (servers)
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Questions?Questions?Questions?
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