Introduction to Telecommunications

1. Chapter 5 Introduction toTelecommunications

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 • conferencing • Computer • conferencing • 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 • E-mail: 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 • 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 Required transmission capacity depends on the application and on the user interface : - administrative input <1000 char/sec - CAD/CAM millions char/sec

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

10. PC-workstation PC-workstation PC-workstation LAN O’Brien 127 - 128 Databases and Software packages Shared hard disk Network Server Shared printer PC-workstation PC-workstation PC-workstation Port to other networks

11. 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 comm. server DB. server Print server CAD server Clients comm. server DB. server O.A. server

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

15. Media and Channels Medium Transmission speed Metal wire .0012Mbps - 10 Mbps Microwave .256 Mbps - 100Mbps Fiber optics .5Mbps - 1,000Mbps • Signals • analog • digital • Cables • Twisted-pair interference • Coaxial cable 20x more expensive 5.500 simultaneous phone calls • Fiber-optic 1 fiber 30.000 phone calls • Wireless • microwave • satellites • Radio, Infrared, Cellular Radio, Mobile computing • GPS global positioning system text: O’Brien p183 - 186

16. Communication hardware • Modems 9.600 14.400 28.800 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 187 - 189

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

18. Star network O’Brien 147 - 148 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 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 PAD = Packet Assembler and Disassembler Data Network PAD E.g..: DCS 1000 - 6000 char/sec , cost / volume data ( X25 ) Due to high connection cost ($ 30.000 year) usage of PAD

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

24. Open systems • 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 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 , ... ) Definition:

25. The OSI model 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 TCP/IP OSI 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 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 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 )