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Chapter 5. Introduction to Telecommunications. Applications of Telecommunications. O’Brien 121. Business Telecommunications. Centralized Distributed Client/server Interorganizational Global. Telecommunications Architectures. Electronic commu- nications system. Electronic meeting

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applications of telecommunications
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
trends
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

technological developments
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

internet revolution
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
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

interactive usage
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

telecommunication components
Telecommunication Components

O’Brien 126

5 components

Telecom

Channels and Media

Telecommunications

software

Telecom

processors

Telecom

processors

End-user

workstation

Computers

slide10

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

wan internetwork
WAN - Internetwork

LAN’s

Mainframe,

hosts

network

in US

network

in Europe

LAN’s

Internet

Tymnet

network

in Australia

Cisco corporation network

client server network
Client/server network

Company A

Internet

Router

Firewall

Intranet

Firewall

Router

Company B

Intranet

Mainframe host system

text: O’Brien p 178

client server
Client - Server

Clients

comm.

server

DB.

server

Print

server

CAD

server

Clients

comm.

server

DB.

server

O.A.

server

the internetwork enterprise
The Internetwork-enterprise

The Internet

Intranets

Extranets

Enterprise

Intranets

Intranets

Supplier

Client

Intranets

Electronic Commerce

Other Organizations

text: O’Brien p 180

media and channels
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

communication hardware
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

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

star network multiplexed
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

bus network
Bus network

Shared usage of a

broadband network

Multidrop lines

- more complex hardware

- simpler cabling system

O’Brien 191

ring networks
Ring Networks

O’Brien 147

Ring Network

- more equal basis

public data networks
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

slide23
ISDN

ISDN

ISDN

Integrated services

Digital network

- universal network for telephone and data

- > 6000 char/sec

open systems
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:

the osi model
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

the tcp ip and the 7 layer osi model
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

osi 7 layer model
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 )