321450 management of information technologymanagement of ... · 1january 2011 [email protected] 17...

321450Management of Information Technology321450321450Management Management of of Information Information TechnologyTechnology

Chapter 8Chapter 8

Telecommunication Technology

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11 January January 20112011 [email protected]@buu.ac.th 33

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


An Overview Of Telecommunications (continued)


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


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


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


Guided transmission media types



� 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



� Wireless communications options

� Wireless transmission involves the broadcast of communications in one of three frequency ranges

� Radio, microwave, or infrared frequencies


Frequency Ranges Used for Frequency Ranges Used for Wireless CommunicationsWireless Communications


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


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


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


WiWi--Fi NetworkFi Network


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


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


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


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


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


A Typical LANA Typical LAN


A Wide Area Network


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


File Server ConnectionsFile Server Connections


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


Client/Server SystemsClient/Server SystemsClient/Server Systems


The Client/Server NetworksThe ClientThe Client//Server Server NetworksNetworks


Client/Server Systems (cont.)Client/Server Systems (cont.)Client/Server Systems (cont.)


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


Telecommunications Hardware (cont.)Telecommunications Hardware Telecommunications Hardware (cont.)(cont.)


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


Telecommunications Hardware (cont.)Telecommunications Hardware Telecommunications Hardware (cont.)(cont.)

� Switch:

� Bridge:

� Router:

� Gateway:


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


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


The Encryption ProcessThe Encryption ProcessThe Encryption Process


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


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


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


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


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


DSL DSL DSL


VoIP Options VoIP Options VoIP Options


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


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


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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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


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


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


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


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


Two Approaches to EDITwo Approaches to EDITwo Approaches to EDI


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


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


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”


Shared WorkspaceShared WorkspaceShared Workspace

� Common work area where:� Colleagues can share documents, issues,

models, schedules, spreadsheets, and all forms of information


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


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)


Questions?Questions?Questions?


� ��

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