Presentation is loading. Please wait.

Presentation is loading. Please wait.

Introduction to Telecommunications

Similar presentations


Presentation on theme: "Introduction to Telecommunications"— Presentation transcript:

1 Introduction to Telecommunications
Chapter 5 Introduction to Telecommunications

2

3 Applications of Telecommunications
O’Brien 121 Business Telecommunications Centralized Distributed Client/server Interorganizational Global Telecommunications Architectures Electronic commu- nications system Electronic meeting systems Business process systems Electronic mail Voice mail Bulletin Board systems Videotex Fascimile Public Information Service Desktop Video conferencing Decision room Computer Teleconferencing Online transaction processing Inquiry/Response EDI / XML Electronic Funds Transfer Activity monitoring Process control Telecommuting

4 Trends O’Brien 122 - 124 Industry trends
Towards a greater number of competitive vendors, carriers, alliances and telecommunications network services. Towards open and interconnected local and global digital networks for voice, data and video, using high-speed fiber-optics and satellites. Technology trends Towards a pervasive use of the internet and enterprise and interorganizational intranets, to support collaborative computing, online business operations and strategic advantage in local and global markets. Application Trends

5 Technological Developments
General trend: Connect everybody to everybody else. Internet-network technologies thousands new hardware- and software products web-browsers, HTML- editors, firewalls Open systems: based on standards connectivity of systems: middleware OSI, TCP/IP Digital technologies higher transmission speed larger information streams more efficient transmission method less errors text: O’Brien : p. 168

6 Internet Revolution Explosive growth Terminology
WWW: inquiry sources of information via graphical browser software electronic mail Usenet: place messages on bulletin board IRC: real time dialogs FTP: file transfer Telnet: login on other systems Other: telephone, video conferencing, ... text: O’Brien : p. 172

7 Telecommunication model
O’Brien 125 Terminals terminal, office equipment , telephones , ... Telecommunications processors modems, multiplexers, front-end processors, ... Telecommunications channels and media copper wires, coaxial cables, fiber optic cables, satellites, ... Computers host computers, front-end computers, network servers, ... Telecommunications control software telecommunication monitors, network operating systems, ... Middleware

8 Interactive usage Interactive usage : - increases considerably the productivity - requires communication networks Required transmission capacity depends on the application and on the user interface : - administrative input <1000 char/sec - CAD/CAM millions char/sec Physical location often crucial factor to decide on the type of connection between the computer and the workstation Standardization is an absolute must in this respect

9 Telecommunication Components
O’Brien 126 5 components Telecom Channels and Media Telecommunications software Telecom processors Telecom processors End-user workstation Computers

10 LAN O’Brien 127 - 128 PC-workstation PC-workstation PC-workstation
Databases and Software packages Shared hard disk Network Server Het gebruik van zulk LAN kan erg uiteenlopende doelen hebben. Het kan bijvoorbeeld ook gebruikt worden om bepaalde middelen beschikbaar te maken voor iedereen die op het LAN aangesloten is. We kunnen hierbij denken aan middelen zoals een electronic mailsysteem , een documentbeheersysteem , een centraal documentatiesysteem of een bestandsarchiveringssysteem die vanwege hun eigenheid voor iedereen toegangkelijk moeten zijn. Het kan echter ook gebruikt worden voor het beschikbaar maken van een snelle laserprinter of specifieke software waarvoor het niet nuttig of te duur is om ze op elke machine afzonderlijk beschikbaar te hebben. Shared printer PC-workstation PC-workstation PC-workstation Port to other networks

11 Cisco corporation network
WAN - Internetwork LAN’s Mainframe, hosts network in US network in Europe LAN’s Internet Tymnet network in Australia Cisco corporation network

12 Client/server network
Company A Internet Router Firewall Intranet Firewall Router Company B Intranet Mainframe host system text: O’Brien p 178

13 Client - Server Clients Clients comm. server DB. server Print server
CAD server Clients comm. server DB. server O.A. server

14 The Internetwork-enterprise
Intranets Extranets Enterprise Intranets Intranets Client Supplier Intranets Electronic Commerce Other Organizations text: O’Brien p 180

15 Media and Channels Signals Cables Wireless
analog digital Cables Twisted-pair interference Coaxial cable 20x more expensive 5.500 simultaneous phone calls Fiber-optic 1 fiber phone calls Wireless microwave satellites Radio, Infrared, Cellular Radio, Mobile computing GPS global positioning system Medium Transmission speed Metal wire .0012Mbps - 10 Mbps Microwave Mbps - 100Mbps Fiber optics .5Mbps - 1,000Mbps text: O’Brien p

16 Communication hardware
Modems bps Transmission mode Simplex 1 circuit , 1 direction Half-duplex 1 circuit, 2 directions, difficult co-ordination Full duplex 2 circuits, 2 directions Transmission accurateness parity bits forward and backward error correction Processors multiplexers frequency, time or statistic time distribution front-end processors to handle routine communication tasks with peripheral equipment text: O’Brien p

17 Network Topology Star Bus Ring
all communications go via the central system Bus can easily be extended at the ends Ring more secure

18 Star network - Efficient , also for high speeds
O’Brien With direct connections Point-to-point lines - Efficient , also for high speeds - With a large number of workstations cabling might be a problem

19 Star network (multiplexed)
Access via multiplexed lines eventually rented - local speed up to 2000 char/sec , 1M char/sec very expensive - internationally 1000 char/sec commonly available

20 Bus network - more complex hardware - simpler cabling system
Shared usage of a broadband network Multidrop lines - more complex hardware - simpler cabling system O’Brien 191

21 Ring Networks O’Brien 147 Ring Network - more equal basis

22 Public data networks Data Network PAD
Packet Assembler and Disassembler Data Network PAD E.g..: DCS char/sec , cost / volume data ( X25 ) Due to high connection cost ($ year) usage of PAD

23 ISDN ISDN - universal network for telephone and data
Integrated services Digital network - universal network for telephone and data - > 6000 char/sec

24 Open systems Definition: An open system is a system where the design has not been made by a supplier but by an accredited standardization organization (eg:ISO , IEEE , ANSI , CODASYL , ... ) This provides the user a better independence from a specific hardware or software supplier and therefore a better guarantee for his investments. It allows the user to make always the most appropriate and optimal choice for each of the sub-systems . Open systems are not yet sufficiently available on the market. The best examples are UNIX and the OSI network model

25 The OSI model diplomatic rules president x president y e.g.: common
Defined by ISO ( International Standard Organization ). OSI ( Open System Interconnect ) describes a framework to subdivide connection problems in networks into almost independent sub-problems . diplomatic rules president x president y e.g.: common language interpreter x interpreter y common key cryptography cryptography common channel operator operator physical link

26 The TCP/IP and the 7 layer OSI model
Application- or process layer Communication services for end users Application layer Correct formatting and coding Presentation layer Support for session initiation Session layer Host-to-host transport layer Data transfers between nodes Transport layer Personen op homologe niveau's communiceren met elkander door beroep te doen op de 'communicatiediensten' die aangeboden worden door de lagere niveau's. De relaties tussen verschillende niveau's hoeven niet identiek te zijn langs beide zijden; in het voorbeeld gebruiken de staatshoofden verschillende talen om met hun tolken te spreken. De zeven lagen . Het OSI model heeft zeven lagen . De drie onderste handelen hoofdzakelijk over de transmissie van ruwe gegevens tussen computers, terwijl de vier bovenste er voor moeten zorgen dat specifieke toepassingen optimaal gebruik zouden kunnen maken van deze transmissiecapaciteit. De fysische layer vervoert bits van een punt naar een ander met een hopelijk kleine, maar toch groter dan nul, kans op transmissiefouten. De verbindingslayer is hoofdzakelijk belast met het verbeteren van de fouten die zich zouden hebben kunnen voordoen in de fysische layer. De networklayer zorgt voor het bepalen van de weg dat een bericht moet volgen doorheen het network. In complexe networken reist een bericht meestal via verschillende segmenten, met onafhankelijke lagen 1 en 2, en in het geval van verschillende doorverbonden networken, zelfs met onafhankelijke lagen 3. De goede werking van de drie onderste lagen wordt gecontroleerd en eventuele fouten verbeterd door de vierde layer, de transportlayer, die alle verschillende networksegmenten globaliseert in een enkel, eind tot eind protokol. De vijfde en zesde lagen, de sessie- en de presentatielayer breiden de diensten van de transportlayer uit met deze specifieke diensten die nodig zijn voor de verschillende toepassingen die door de zevende layer geimplementeerd worden. Electronische post en gedistribueerde bestandensystemen zijn voorbeelden van toepassingen die reeds behoorlijk gestandardizeerd zijn op niveau zeven. Internet-protocol IP routing of connections Network layer network-interface Support for error-free data transfer data link Physical layer physical access to communication media Physical layer O’Brien 193

27 OSI 7-Layer Model 7. Application (user application program)
O’Brien 150 7. Application (user application program) 6. Presentation (user interface / screen display ) 5. Session ( exchange between two nodes on the network ) 4. Transport ( protocol for encoding messages ) 3. Network ( mechanism for separating multiple messages ) 2. Link ( data encoding schemes ) 1. Physical ( wires, connectors , voltage )


Download ppt "Introduction to Telecommunications"

Similar presentations


Ads by Google