Computer Communications Network
COMPUTER COMMUNICATION NETWORKS Objectives • • • • • What is telecommunication History of telecommunication Role of telecommunication in Organizations Interpersonal communication applications Computer networks What is telecommunication? “Transmission of data or audible/visible information by electrical/electronic means” e. g. telephone, telegraph, radio, television, computer networks (Internet) Basic elements 1. Transmitter : takes information and converts it to a signal 2. Transmission medium :over which the signal is transmitted 3.
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Receiver : that receives the signal and converts it back into usable information. e. g. a radio broadcast: broadcast tower (Transmitter) free space (transmission medium) radio (receiver) Basic Elements • Transceiver : a single device that acts as both a transmitter and receiver, e. g a mobile phone is a transceiver • Point-to-point communication : Telecommunication over a phone line • Broadcast : Telecommunication through radio broadcasts (one powerful transmitter and numerous receiver) History of Telecommunication Alexander Graham Bell Patented the Telephone in 1876. • Telephones came in pairs. • Separate wire had to be sprung to all connected houses. History of Telecommunication Copy of the original phone of Alexander Graham Bell at the Musee des Arts et Metiers in Paris History of Telecommunication • Bell formed the Bell Telephone Company, which opened its first switching office in 1878 (fig. a) • For long distance calls between cities multilevel switching offices were formed. (fig. b) Fig. a Fig. b Role of telecommunication in Organizations
Enterprise collaboration system : Information systems that use a variety of information technologies to help people work together • Communication • Coordination • Collaboration Interpersonal Communication Applications: Electronic Mail Electronic Mail: A store and forward method of composing, sending, storing, and receiving messages over electronic communication systems Interpersonal Communication Applications: Internet Relay Chat • Internet Relay Chat : a form of real-time Internet chat or synchronous conferencing. E. g. IRC Clients such as pIRCh, VIRC, mIRC, etc.
A Screenshot of Xchat, an IRC client. Interpersonal Communication Applications: Facsimile • Latin word fac simile, “make similar”, i. e. “make a copy“ • A telecommunications technology used to transfer copies (facsimiles) of documents, especially using affordable devices operating over the telephone network. – Scanner – Modem – Printer Interpersonal Communication Applications: Voice Mail • Voicemail (or voice mail, vmail or VMS, sometimes called messagebank) is a centralized system of managing voice messages for a large group of people • Features: Answer many phones at the same time – Store incoming voice messages in personalized mailboxes – Enable users to forward received messages to another voice mailbox – Send messages to one or more other user voice mailboxes Interpersonal Communication Applications: Videoconferencing “A set of interactive telecommunication technologies which allow two or more locations to interact via two-way video and audio transmissions simultaneously” Computer Networks • Centralized computing – Main Computer – Dumb Terminals Computer Networks • Distributed computing Tasks are divided among several computers. • Collaborative computing – A computing technology that permits geographically dispersed teams to develop, edit and use common databases or “repositories” of information. Cloud computing • The provision of computational, software, data access, and storage services on demand via a network. • They do not require end-user knowledge of the physical location and configuration of the system that delivers the services. • A provider’s offering of abstracted Internet services is often called The Cloud.