-
7/28/2019 05 Telecom m
1/27
Introduction toTelecommunications
Chapter 5
-
7/28/2019 05 Telecom m
2/27
-
7/28/2019 05 Telecom m
3/27
Applications of Telecommunications
Business
Telecommunications
Telecommunications
Architectures
Electronic commu-
nications system
Electronic meeting
systems
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
Computerconferencing
Teleconferencing
Online transactionprocessing
Inquiry/Response EDI / XML Electronic Funds Transfer Activity monitoring Process control Telecommuting
OBrien 121
-
7/28/2019 05 Telecom m
4/27
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.
OBrien 122 - 124
Application Trends
-
7/28/2019 05 Telecom m
5/27
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: OBrien : p. 168
-
7/28/2019 05 Telecom m
6/27
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: OBrien : p. 172
-
7/28/2019 05 Telecom m
7/27
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
OBrien 125
-
7/28/2019 05 Telecom m
8/27
Interactive usage
Physical location often crucial factor to decide on the
type of connection between the computer and theworkstation
Standardization is an absolute must in this respect
Interactive usage : - increases considerably the productivity
- requires communication networks
Required transmission capacity depends on the applicationand on the user interface :
- administrative input
-
7/28/2019 05 Telecom m
9/27
Telecommunication Components
End-user
workstation
Telecommunicationssoftware
Computers
Telecomprocessors
Telecomprocessors
TelecomChannels and Media
5 components
OBrien 126
-
7/28/2019 05 Telecom m
10/27
LANPC-workstation PC-workstation
PC-workstationPC-workstationPC-workstation
PC-workstation
Network
Server
Port to
other networks
Shared hard disk
Shared
printer
Databases andSoftware packages
OBrien 127 - 128
-
7/28/2019 05 Telecom m
11/27
WAN - Internetwork
network
in US
network
in Europe
Mainframe,
hosts
Internet
network
in Australia
LANs
LANs
Tymnet
Cisco corporation network
-
7/28/2019 05 Telecom m
12/27
Client/server network
Intranet
Company A
IntranetCompany B
Mainframe host system
Router
Router
Internet
Firewall
Firewall
text: OBrien p 178
-
7/28/2019 05 Telecom m
13/27
Client - Server
Clients
Clients
comm.
server
comm.server
DB.server
Printserver
DB.server
O.A.server
CADserver
-
7/28/2019 05 Telecom m
14/27
The Internetwork-enterprise
The Internet
Intranets
Intranets
Intranets
Intranets
Extranets
Client
Enterprise
Supplier
Other Organizations
Electronic Commerce
text: OBrien p 180
-
7/28/2019 05 Telecom m
15/27
Media and Channels
Signals analog
digital
Cables Twisted-pair interference
Coaxial cable 20x more expensive5.500 simultaneous phone calls
Fiber-optic1 fiber 30.000 phone calls
Wireless
microwave satellites
Radio, Infrared, Cellular Radio, Mobile computing
GPS global positioning system
Medium Transmission speedMetal wire .0012Mbps - 10 Mbps
Microwave .256 Mbps - 100Mbps
Fiber optics .5Mbps - 1,000Mbps
text: OBrien p183 - 186
-
7/28/2019 05 Telecom m
16/27
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
Processorsmultiplexers frequency, time or statistic time distribution
front-end processors to handle routine communication taskswith peripheral equipment
text: OBrien p 187 - 189
-
7/28/2019 05 Telecom m
17/27
-
7/28/2019 05 Telecom m
18/27
Star network
With directconnections
- Efficient , also for high speeds
- With a large number of workstations cabling might be a problem
OBrien 147 - 148
Point-to-point lines
-
7/28/2019 05 Telecom m
19/27
Star network (multiplexed)
Access viamultiplexedlineseventually rented
- local speed up to 2000 char/sec , 1M char/sec very expensive
- internationally 1000 char/sec commonly available
-
7/28/2019 05 Telecom m
20/27
Shared usage of abroadband network
- more complex hardware- simpler cabling system
Multidrop lines
Bus network
OBrien 191
-
7/28/2019 05 Telecom m
21/27
Ring Networks
Ring Network
- more equal basis
OBrien 147
-
7/28/2019 05 Telecom m
22/27
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
-
7/28/2019 05 Telecom m
23/27
ISDN
ISDN
- universal network for telephone and data
- > 6000 char/sec
ISDNIntegrated servicesDigital network
-
7/28/2019 05 Telecom m
24/27
Open systems
This provides the user a better independence from aspecific hardware or software supplier and therefore abetter 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 , ... )
-
7/28/2019 05 Telecom m
25/27
The OSI modelDefined by ISO ( International Standard Organization ).
OSI ( Open System Interconnect ) describes a framework tosubdivide connection problems in networks into almostindependent sub-problems .
e.g.:president x president y
interpreter x
cryptography cryptography
operator operator
diplomatic
rules
commonlanguage
commonkey
commonchannel
physical link
interpreter y
-
7/28/2019 05 Telecom m
26/27
The TCP/IP and the 7 layer OSI model
Application- or
process layer
Host-to-host
transport layerInternet-protocol
IP
network-interface
Physical layer
Application layer
Presentation layer
Session layer
Transport layer
Network layer
data link
Physical layer
Communication services
for end users
Correct formatting
and coding
Support for sessioninitiation
Data transfers between
nodes
routing of
connections
Support for error-free
data transfer
physical access to
communication media
OBrien 193
TCP/IP OSI
-
7/28/2019 05 Telecom m
27/27
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 )
OBrien 150
