Corso “Telematica e Reti”

Università Degli Studi Di Roma “Tor Vergata” – Facoltà Di Ingegneria

DIPARTIMENTO DI INGEGNERIA DELL’IMPRESA

“Mario Lucertini”

Anno Accademico 2012-2013

Prof. Francesco Vatalaro

Prof. Romeo Giuliano

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Some References1

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Introduction to Telecommunications

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Introduction to Telecommunications

Definition of Telecommunications

Telecommunications technology:

• evolved from mechanical to electrical form

• electrical and/or optical signals

• mono- or bi-directional communication

What is telecommunications? Webster’s calls it “communications at a distance”. The

IEEE Standard Dictionary defines telecommunications as “the transmission of signals

over long distance, such as by telegraph, radio, or television”.

Telecommunication encompasses the

communication at a distance

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Telecommunications networks interconnected

into a global system

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Telecommunications

communication at a distance

of voice, data, and image information

“Telematica e Reti” -- From Wikipedia →

-Telematics typically is any integrated use of

telecommunications and informatics, also known as ICT

(Information and Communications Technology)

- A computer network, or simply a network, is a collection of computers and

other hardware components interconnected by communication channels that

allow sharing of resources and information

Role of Telecommunications

Telecommunications plays an essential role on many areas of everyday life.

Each of us uses telecommunications services and services that rely on

telecommunications daily.

Here are some examples of services that depend on telecommunications:

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• Banking, automatic teller machines, telebanking

• Aviation, booking of tickets

• Sales, wholesale and order handling

• Credit card payments at gasoline stations

• Booking of hotel rooms by travel agencies

• Material purchasing by industry

• Government operations, such as taxation.

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End-Users, Nodes, ConnectivityEnd-users (clients, subscribers, etc.) provide the inputs (“source”) to the network and are

recipients (“destination”) of network outputs.

End-user employs what is called an I/O (input/output device): it may be a PC, telephone,

cellular phone, smart phone, facsimile, conference TV equipment, etc.

End-users usually connect to nodes: a node is a point or junction in a transmission

system where lines and trunks meet.

A connectivity links an end-user to a node, and from there possibly through other nodes

to some final end-user destination with which the initiating end-user wants to

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to some final end-user destination with which the initiating end-user wants to

communicate. Figure below illustrates this concept.

The IEEE defines a connection as “an association of channels, switching systems, and

other functional units set up to provide means for a transfer of information between

two or more points in a telecommunications network.”

Functions of end-users, nodes, and connectivity

1800: Alessandro Volta discovers the primary battery

1836: Samuel Morse invents Telegraphy

1876: Alexander Bell perfects acoustic

transducer and is accredited inventor

of Telephony

1901: Guglielmo Marconi’s first successful transatlantic

Radio transmission (“Can you hear anything, Mr. Kemp?”)

1918: H. C. Armstrong perfects

the superheterodyne radio receiver Development of telecommunications

Telecommunications: a Bit of History6

the superheterodyne radio receiver

1937: Alec Reeves conceives pulse code modulation (PCM)

1948: Claude Shannon publishes his founding paper

on information theory

1954: J. R. Pierce proposes satellite communications

1969: ARPANET, the precursor of INTERNET, is created

1976: Ethernet LAN invented by Metcalfe et al.

1980: Cellular mobile networks start being put into service

1989: Proposal for a World Wide Web (WWW) by Tim Berners-Lee7

Development of telecommunications

Villa Griffone, Pontecchio (BO),

where Marconi invented the

Radio (1895)

2000: Launch of the UMTS service.

Transoceanic Telegraphy Network in 19017

8Source: http://matt-welsh.blogspot.com/2010/08/book-review-victorian-internet.html

Standardization

Standards are necessary to achieve interoperability, compatibility, and required

performance in a cost-effective manner:

• enable competition

• lead to economies of scale

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Different standards in Europe, Japan, and the United States

Standards make the interconnection of systems from different vendors possible

Standards make users and network operators vendor-independent

Standards make international services available

Interested parties: groups that are interested in

standardization and participate in standardization work.

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Standards Organizations

National

Standardization

Authorities

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European Standards Organizations American Standards Organizations

Global Organizations Other Organizations10

An example of standard: ISO/OSIThe seven-layer stack structure, called ISO-OSI (International Standards Organization - Open

Systems Interconnection) architecture, is a useful conceptual reference to organize the

functions of a telecommunications network.

In general the functions of the generic layer, say layer n, regardless of its location in the ISO-

OSI stack, are to provide a set of services to the upper layer, i.e. layer n+1, hiding the details

of how the services are actually implemented by layer n-1.

Data Link Layer: task of transferring data

between adjacent nodes, providing the

Examples: Layer 1 e Layer 2

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MEDIUM

Physical

Data Link

Network

Transport

Session

Presentation

Application

MAC

LLC

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3

4

5

6

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2Physical Layer (PHY): includes equipment for

physical cabling or wireless connection, and

also deals with the electrical and mechanical

specifications, control of interference and

collisions, and any other basic aspects of the

transmission in order to transmit the

information in raw form.

between adjacent nodes, providing the

functional and procedural means to transfer

data between network entities and the means

to detect and possibly correct errors that may

occur in the underlying physical layer.

ISO/OSI functional stack

The Telecommunications Business

In the past, telecommunications were a protected business area.

PTTs had control over standardization in international standardization

bodies and monopoly in providing telecommunications services in their respective

Countries.

Competition was not allowed.

Latter part of the 1980s: the deregulation of the telecommunications business

started in the USA and in Europe (first in UK, then in the EU).

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started in the USA and in Europe (first in UK, then in the EU).

New operators obtained licenses to provide local and long-distance

telephone and data services, as well as mobile telecommunications services.

Deregulation of the telecommunications business promoted economical

efficiency: reduced tariffs and one driver for increased service quality.

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Competition became the rule: liberalization and (very often) privatization.

Main public tariffs dynamics (Italy) TLC services prices dynamics (EU)

-15 -32

-26

-15

+40

+66 0

0

+27

Tariffe telefoniche (Italia)Tariffe TLC (Italia)

Reduced Tariffs in a Liberalized Economy12

AGCOM annual report (year 2010)

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Italy: over the past decade the basic telephone service was the only one among public

services to become cheaper. Telephone prices fall by 15% in absolute value (while water

increase was +66%, transport, gas, energy was about +40% and post was + 27%).

Europe: in the past decade the portfolio of TLC services tariffs fell everywhere, with an

average of about 26%. With an average decrease of over 30%, Italy is the country where

tariffs fell more (in Spain and France decrease was only 15%).

Note: in Telecommunications, tariffs decrease both for the effect of competition and

for the effect of technology innovation (“Moore-law related”). It is difficult to separate

the relative impact.

(1905)

(1888)

(1873)

(1878)

(1962)

(1998)

(1928)

(1976)

(1976)

(1943)

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Tempo necessario per raggiungere una famiglia su due:

Automobile: 85 anni Telefono: 75 anni Televisione: 30 anni Internet: 8 anni

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