Telecommunications Infsy 540 Dr Ocker Chapter 7 Telecommunications

Telecommunications Infsy 540 Dr. Ocker

Chapter 7: Telecommunications, the Internet, and Information System Architecture First Edition Foundations of Information Systems Vladimir Zwass Irwin/Mc. Graw-Hill © The Mc. Graw-Hill Companies, Inc. . , 1998

Telecommunications n What is telecommunications?

Telecommunications n communication of information by electronic means, usually over some distance

Telecommunications n need to understand the – capabilities – costs, – benefits n of alternative communications technologies and how to maximize their benefits for their organizations

information superhighway n n n high-speed digital telecommunications networks that are national or worldwide in scope and accessible by the general public a web of high-speed digital telecomm. networks delivering information, education, and entertainment services to offices and homes virtually eliminates the barriers of time and place

information superhighway n most well-known implementation of the info. superhighway is the Internet

telecommunication system n n collection of compatible hardware and software arranged to communicate information from one location to another can transmit – – text graphic images voice video

Telecommunications system components n n n 1. computers to process info 2. terminals (or any input/output devices) to send and receive data 3. communications channels – links by which data or voice are transmitted between sending and receiving devices in a network

Telecommunications system components n 4. communications processors provide support functions for data transmission and reception; – e. g. modems, multiplexes, controllers, front -end processors n 5. communications software - controls input and output activities and manages other functions of network

Functions of telecommunications systems · · transmission of information establishes the interface between sender and receiver routes messages along most efficient paths performs processing of information to ensure that the right message gets to the right receiver

Functions of telecommunications systems · performs editing of data · checks for errors · converts messages from one speed to another · e. g. from speed of computer to speed of communications line · controls flow of information

Protocols n telecomm. network contains diverse hardware and software components that need to work together to transmit information

Protocols n n different components in a network can communicate by following a common set of rules that allows them to “talk” to each other protocol - set of rules and procedures that govern transmission between components in a network

principal functions of protocols n n n to identify each device in the communication path to secure the attention of the other device to verify correct receipt of the transmitted message to verify that a message requires retransmission because it cannot be correctly interpreted to perform recovery when errors occur

Types of signals: analog and digital n n information travels through a telecommunications system in form of electromagnetic signals represented in 2 ways - analog and digital

Types of signals: analog and digital n analog signal - continuous waveform that passes through a communications medium – used for voice communications n digital signal - discrete waveform that transmits data coded into 2 discrete states as 1 -bits and 0 -bits, which are represented as on-off electrical impulses – used for data communications

Types of signals: analog and digital n n if a telecommunications system is set up to process analog signals - a digital signal cannot be processed without some alterations all digital signals must be translated into analog signals before they can be transmitted in an analog system

Modems n n modem - modulate/demodulate translates the digital signals of computer into analog form for transmission over ordinary telephone lines, or translates analog signals back into digital form for reception by a computer

Telecommunications over a Telephone Line Digital Computer Modem Analog Telephone Link Digital Modem Computer

communication channels n n means by which data are transmitted from one device in a network to another links by which data or voice are transmitted between sending and receiving devices in a network

Types of communications channels n a channel can utilize different kinds of telecomm. transmission media: – twisted wire – coaxial cable – fiber optics – terrestrial microwave – satellite – radio (wireless) transmission

twisted wire n n pairs of twisted copper wires phone lines

coaxial cable n n thickly insulated copper wire used for cable TV

fiber optic cable n consists of thousands of strands of clear glass fiber – thickness of human hair n n fast, light, and durable data transmitted as light impulses

Radio (wireless) transmission n n sends signal through air or space without any physical tether e. g. cellular radio systems used for mobile telephones

microwave n n n high-volume long-distance, point-topoint transmission high-frequency radio signals are transmitted through atmosphere from one terrestrial transmission station to another transmission only in straight line

satellites n n serve as relay stations for microwave signals use to transmit large amounts of data over long distances

LANS (local area networks) n cover limited distance – usually one building or several buildings in close proximity n n n require their own communications channels allow orgs. to share hardware and software many applications require high-capacity networks – e. g. email, graphics, video conferencing

LANS n used to link PCs within a building to share information and peripheral devices – e. g. laser printers

Servers n n computer in a network that stores various programs and data files for users of a network; determines access and availability in the network contains the LANS’ network operating system – manages the server – routes and manages communications on the network

Gateway n n network gateway - connects the LAN to public networks (e. g. telephone network, other corporate networks) can connect dissimilar networks by translating from one set of protocols to another

LAN technology n consists of cabling – twisted wire, coaxial, or fiber optic n n n or wireless technology that link computers and software to control LAN activities

main disadvantage of LAN n Inflexible – need new wiring each time the LAN is moved

Wide-area Networks n cover broad geographical distances – ranging from several miles to across continents n n may consist of a variety of cable, satellite, and microwave technologies common carriers - licensed by government to provide communications services to public (e. g. AT&T, MCI)

Wide-area Networks n n can consist of combination of switched and dedicated lines switched lines – telephone lines that can be used for data transmission – call is routed or switched through paths to destination n dedicated line – continuously available for transmission – can be leased or purchased from common carriers

A Wide Area Network Mainframe (Headquarters) Minicomputer (Division A) LAN Minicomputer (Division B) LAN Minicomputer (Division C) . . . Local Workstations (Microcomputers and Other Terminals)

Telecommunications Equipment in a Wide Area Network

telecommunications for competitive advantage n n many of the strategic applications would not be possible without telecommunications firms that fail to consider telecommunication in their strategic plans will fall behind

Applications – email – voice mail – fax – teleconferencing – digital information services – videoconferencing – electronic data interchange (EDI)

Applications n digital information services – obtain information from outside of the company instantly – e. g. stock prices, legal research, news articles etc. n includes electronic bulletin boards

Applications n Teleconferencing – allows groups of people to confer simultaneously via telephone or electronically (computer conferencing) n videoconferencing – teleconferencing with a view

Applications n EDI - electronic data interchange – direct computer-to-computer exchange between two organizations of standard business transaction documents such as invoices, bills, purchase orders. n EDI saves money and time because transactions can be transmitted from one IS to another through telecomm. Network – eliminates printing and handling of paper at one end and inputting of data at the other

The Internet & Electronic Commerce

Internet n n Global network of computer netwokrs without a centralized control the “information superhighway”

To connect to the Internet n n Network has to send and receive data packets using the TCP/IP protocol suite serieis of routers forwards packets to tehir destination

World-wide Web (WWW) n n n Software that organizes information on the Internet into a network of interrelated electronic documents Web is a client/server system collection of electronic sites stored on thousands of servers all over the world

Electronic commerce n n Sharing business information, maintaining business relationships and conducting business transactions by means of telecommunications networks doing business electronically – replacing most of the paperwork and telephone work with compouter-mediated information and transaction exchange

intranets n n Internal networks of web sites set up on corporate LANS and WANs separated from the public Internet by a firewall prevents access from the Internet but allows access to the Internet