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
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