Introduction toTelecommunications

Chapter 5

Applications of Telecommunications

BusinessTelecommunications

TelecommunicationsArchitectures

Electronic commu- nications system

Electronic meetingsystems

Business process systems

• Centralized• Distributed• Client/server• Interorganizational• Global

• Electronic mail• Voice mail• Bulletin Board systems• Videotex• Fascimile• Public Information Service

• Desktop Videoconferencing

• Decision roomconferencing

• Computer conferencing

• Teleconferencing

• Online transaction processing

• Inquiry/Response• EDI / XML• Electronic Funds Transfer• Activity monitoring• Process control• Telecommuting

O’Brien 121

Trends

Towards a greater number of competitive vendors, carriers, alliancesand telecommunications network services.

Industry trends

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 interorganizationalintranets, to support collaborative computing, online business operations and

strategic advantage in local and global markets.

O’Brien 122 - 124

Application Trends

Technological Developments

General trend: Connect everybody to everybody else. Internet-network technologies

thousands new hardware- and software productsweb-browsers, HTML- editors, firewalls

Open systems: based on standardsconnectivity of systems: middlewareOSI, TCP/IP

Digital technologieshigher transmission speed larger information streamsmore efficient transmission method less errors

text: O’Brien : p. 168

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

Telecommunication model 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

O’Brien 125

Interactive usage

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

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

Telecommunication Components

End-user workstation

Telecommunicationssoftware

Computers

Telecomprocessors

Telecomprocessors

TelecomChannels and Media

5 components

O’Brien 126

LANPC-workstation PC-workstation

PC-workstationPC-workstationPC-workstation

PC-workstation

NetworkServer

Port toother networks

Shared hard disk

Sharedprinter

Databases and Software packages

O’Brien 127 - 128

WAN - Internetwork

networkin US

networkin Europe

Mainframe,hosts

Internet

networkin Australia

LAN’s

LAN’s

Tymnet

Cisco corporation network

Client/server network

Intranet

Company A

IntranetCompany B

Mainframe host system

Router

Router

Internet

Firewall

Firewall

text: O’Brien p 178

Client - Server

Clients

Clients

comm.server

comm.server

DB.server

Printserver

DB.server

O.A.server

CADserver

The Internetwork-enterprise

The Internet

Intranets

Intranets

Intranets

Intranets

Extranets

Client

Enterprise

Supplier

Other Organizations

Electronic Commerce

text: O’Brien p 180

Media and Channels Signals

analogdigital

CablesTwisted-pair interference Coaxial cable 20x more expensive

5.500 simultaneous phone calls

Fiber-optic 1 fiber 30.000 phone calls

Wirelessmicrowavesatellites

Radio, Infrared, Cellular Radio, Mobile computing GPS global positioning system

Medium Transmission speedMetal wire .0012Mbps - 10 MbpsMicrowave .256 Mbps - 100MbpsFiber optics .5Mbps - 1,000Mbps

text: O’Brien p183 - 186

Communication hardware

Modems 9.600 14.400 28.800 bps

Transmission modeSimplex 1 circuit , 1 direction

Half-duplex 1 circuit, 2 directions, difficult co-ordinationFull duplex 2 circuits, 2 directions

Transmission accuratenessparity bits forward and backward error correction

Processorsmultiplexers frequency, time or statistic time distribution front-end processors to handle routine communication tasks

with peripheral equipment

text: O’Brien p 187 - 189

Network Topology

Starall communications go via the central system

Buscan easily be extended at the ends

Ringmore secure

Star network

With directconnections

- Efficient , also for high speeds- With a large number of workstations cabling might be a problem

O’Brien 147 - 148

Point-to-point lines

Star network (multiplexed)

Access viamultiplexedlineseventually rented

- local speed up to 2000 char/sec , 1M char/sec very expensive - internationally 1000 char/sec commonly available

Shared usage of abroadband network

- more complex hardware- simpler cabling system

Multidrop lines

Bus network

O’Brien 191

Ring Networks

Ring Network

- more equal basis

O’Brien 147

Public data networks

PAD

Data Network

E.g..: DCS 1000 - 6000 char/sec , cost / volume data ( X25 ) Due to high connection cost ($ 30.000 year) usage of PAD

PAD =Packet Assemblerand Disassembler

ISDN

ISDN

- universal network for telephone and data- > 6000 char/sec

ISDNIntegrated servicesDigital network

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

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 , ... )

The OSI modelDefined by ISO ( International Standard Organization ).

OSI ( Open System Interconnect ) describes a framework to subdivide connection problems in networks into almost independent sub-problems .

e.g.: president x president y

interpreter x

cryptography cryptography

operator operator

diplomaticrules

commonlanguage

commonkey

commonchannel

physical link

interpreter y

The TCP/IP and the 7 layer OSI model

Application- orprocess layer

Host-to-hosttransport layer

Internet-protocolIP

network-interface

Physical layer

Application layer

Presentation layer

Session layer

Transport layer

Network layer

data link

Physical layer

Communication services for end users

Correct formattingand coding

Support for sessioninitiation

Data transfers betweennodes

routing ofconnections

Support for error-freedata transfer

physical access tocommunication media

O’Brien 193

TCP/IP OSI

OSI 7-Layer Model

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 )

O’Brien 150