Telecom Basics Tutorial Covers Principles, Systems & Concepts

EEE402F-b / EEE526Z
Convergent Networks

Special Tutorial on Telecommunications

H Anthony Chan
h.a.chan@ieee.org
http://www.eng.uct.ac.za/~achan
Mqhele E Dlodlo
mdlodlo@ebe.uct.ac.za
http://www.uct.ac.za/courses/eee_mdlodlo/
Department of Electrical Engineering
University of Cape Town

Telecommunication Basics Tutorial
Mqhele E. Dlodlo & H. Anthony Chan EEE402F Module B: Convergent Voice and Data Network 6 November 2012

Aims

♦ To review the Basic Principles of Telecommunications
♦ To outline necessary background knowledge for higher level
systems analysis, design, selection and management
♦ To identify critical systems characteristics
♦ To identify telecommunication systems as:
 Radio Systems
 Data Systems, and
 Television Systems
♦ To outline a sample of Business Services offered by
Telecommunication Systems
♦ To cite some strategic issues facing telecommunication
systems


Objectives

♦ To demonstrate an understanding of the
place of data communications in
telecommunication systems
♦ To show an appreciation of the ubiquity of
telecommunications in today’s society
♦ To show an ability to identify and explain
system characteristics


Telecommunication

♦ The extension of communication over a distance,
under the practical constraints of attenuation, noise
and interference such that something may be lost
in the process; hence the term 'telecommunication'
covers all forms of distance and/or conversion of
the original communications, like
 radio,
 telegraphy,
 television,
 telephony,
 data communication and
 computer networking.


Telecommunication Systems

♦ A telecommunication system receives and converts some
original information energy (voice, music, video, data) into
an electronic information signal, transmits the signal and
converts the signal at the destination back to its desired
form. No live transfer!
♦ Examples include:
 Telephone networks
 Data communication networks
 Computer networks
 Broadcast networks – radio and television
♦ Main Types:
 Line systems
 Radio systems
 Satellite-based systems


Elementary Concepts – Wire-line

♦ A line system passes the electronic
information signal down a wire, cable or fibre
link (or a combination of these)
♦ The propagation speed can be as low as
60% the speed of light in some media.
♦ A source encoder converts analogue
information into a Pulse Code Modulated
(PCM) signal before transmission


Elementary Concepts - Wireless

♦ In a radio system, the source converts the energy
into an electromagnetic radio signal to transmit
over a radio link
♦ The propagation proceeds at the speed of light
♦ In either case, there will be signal degradation due
to electronic noise and other mechanisms
♦ The objective of systems design is to minimise
such distortions
♦ Interactive telecommunication systems require two-
way or duplex channels, but broadcast systems
need only simplex or one-way channels


Line System Characteristics

♦ Attenuation and Noise
♦ Modulation: AM, FM, PM, PCM
♦ Twisted pair copper wires
♦ Coaxial cable or tube
♦ Optical fibre
♦ Transmission line characteristics


Wireless System Characteristics

♦ Electromagnetic radio waves:
 Surface wave
 Sky wave (via ionosphere)
 Space wave (line-of-sight and reflected)
 Satellite transponder radiation
 Tropospheric scatter
♦ Electromagnetic light waves (pulsed infra red laser light)
♦ Propagation
♦ Antenna design
♦ Satellite link design
♦ Land-mobile access network design
♦ Maritime communication systems design
♦ Error-control coding
♦ Multiple access control schemes
♦ Detection schemes, e.g. joint detection


Data Networks and Systems

♦ Open Systems Interconnection Model
♦ Internetworking Model
♦ Data services and packet switching
♦ Frame mode bearer services
♦ Local area networks (LANs)
♦ Wide area networks (WANs)


Signalling, Transmission and Switching

♦ Signalling: passing of information from one point to another
for setting up or supervision of a telephone call or a data
exchange session
♦ Transmission: dispatch and propagation of a signal,
message, or other form of information by any means, such
as by telegraph, telephone, radio, television, or facsimile via
any medium, such as wire, coaxial cable, microwave, optical
fibre, or radio frequency.
♦ Switching: the process of making connections and relaying
information between a calling party and a called party
usually through a combination of space and time division
multiplex apparatus in the exchange fabric


ITU-T Signalling System No. 7

♦ Is extended to data and multimedia control
♦ Separates signalling and user traffic
♦ Provides better support for services like:
network management
Network maintenance
Centralised call accounting


Transmission

♦ The central problem of transmission is the conveyance of signals as
waves over distances significant with respect to the wavelengths
involved
♦ Large volumes of data are regularly transmitted sequentially making it
necessary to encode the information into a signal
♦ A travelling sinusoidal wave progressively experiences increased phase
delay and attenuation with distance in the direction of propagation
♦ The main characteristics of transmission media are the propagation
constant, characteristic impedance and reflection coefficient
♦ Transmission media include twisted copper wire pairs, coaxial cables,
strip lines, waveguides, optical fibre and free space
♦ Transmission system design and analysis relies greatly on
electromagnetic theory as well as differential and integral calculus


Switching Principles

♦ Goal: to enable any terminal (telephone, data terminal,
computer) as requested by the calling party
♦ Switching centre – telephone exchange
♦ Full mesh – backbone or core networks
♦ Digital switching – time division stages shift PCM words in
time between incoming and outgoing channels, multiplexing
them onto different time slots
♦ Space division – provides direct physical paths right through
the exchange connecting the local loops of one subscriber
to that of another.


Evolving Core Switching Technologies

♦ Frame Relay (FR)
♦ Asynchronous Transfer Mode (ATM)
♦ Internet Protocol (IP)
♦ IP Virtual Private Network (IP VPN)


Business Services

♦ Private Automatic Branch Exchange, key-phones, Centrex
♦ Virtual Private Networks (VPN)
♦ Private networks and leased lines
♦ Conference calling
♦ ISDN supplementary services
♦ Mobile telecommunication systems – paging, SMS, voice,
remote login, email, Internet access
♦ Free-phones – “0800” series
♦ Facsimile
♦ Interactive services – teletex, teletext, email, EFT-POS,
credit cards, smart cards, voice mail
♦ Voice over IP

Personal Consumer Services

♦ Television Services
 High Definition Television (HDTV)
 Direct Satellite Television (DSTV/DBS)
 Cable Television
♦ Asynchronous Digital Subscriber Line (ADSL) and variants
♦ Wireless Local Loop
♦ Dial-up Email or Internet Access
♦ Telephone Banking
♦ Internet Banking
♦ Automatic Teller Machines
♦ Phone Cards
♦ Emergency Services
♦ Online Directory Services
♦ Online Shopping


Strategic Issues

♦ Telecommunications network numbering
♦ Telecommunications standards
♦ Telecommunications network management
 Centralised maintenance
 Reliability
 Voice tariffs
 Forecasting future demand
♦ Telecommunications security
♦ Telecommuting
♦ Convergence of technologies

EEE402F-b / EEE526Z
Convergent Networks

“The ability to communicate with high speed network
at affordable price is important to the people,
business, and industry in every country to complete
in global market.”
www.uct.ac.za/depts/commnetwork/
© 2005

Ref: G. Langley & J. P. Ronyne; Telecommunications
Primer, 4/e; Pitman Publishing, 1993


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