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When: 4/5/05 |
Place: UPR, Mayaguez 10:30 AM S205 |
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Background
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Scope and Objectives
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Network synchronization has
gained increasing importance in telecommunications throughout the last
thirty years: digital switching, SDH/SONET, ATM, CDMA, GSM and UMTS are
striking examples where network synchronization has been proven to affect
quality of service.
In this tutorial lecture,
synchronization processes at different levels in telecommunications are
first reviewed and fundamental definitions about timing of digital signals,
jitter and wander are introduced. Major topics of this tutorial are: timing
aspects in SDH/SONET networks; architectures and requirements for timing
transfer in PDH, SDH/SONET, ATM and fixed/mobile telephone networks;
strategies, standards, architectures and clocks for synchronization
networks; basic principles of Network Time Protocol. |
This tutorial provides a quick
but broad overview on several topics that are not commonly addressed in
literature. It does not go deep into details of special topics, but rather
aims at making the audience aware of the main concepts and issues in
synchronization of digital telecommunications networks. In particular, the
participants will learn:
1)
That the word “synchronization” is used in several contexts in
telecommunications, addressing a wide spectrum of different timing issues;
2)
Basic concepts such as jitter and timing relationships between timing
signals;
3)
Timing aspects in SDH/SONET networks, such as the main causes of jitter in
SDH/SONET networks and what are synchronizers, desynchronizers and pointer
processors;
4)
How network synchronization issues evolved with the telephone networks,
beginning from old FDM networks up to the latest technologies, through PDH,
SDH/SONET, ATM and mobile telephone cellular networks;
5)
Strategies and standard architectures for synchronization distribution;
6)
Principles of operation of clocks for synchronization networks;
7)
Principles of Network Time Protocol (NTP).
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About Dr. Stefano Bregni |
Registration |
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Stefano
Bregni
was born in Milano, Italy, in
1965. He received his Dr. Ing. degree in Telecommunications Engineering from
Politecnico di Milano.
In 1991 he joined SIRTI S.p.A.,
where he was involved in SDH transmission systems testing and in network
synchronization issues, with special regard to clock stability measurement.
From 1994 to 1999, he was with CEFRIEL (consortium of private companies with
Politecnico di Milano) as head of the Transmission Systems Dept. Since 1999,
he has been Assistant Professor at Politecnico di Milano, Dept. of
Electronics and Information, where he teaches telecommunications networks
and transmission networks.
He has been Senior Member of
IEEE since 1999. He is Distinguished Lecturer of the IEEE Communications
Society, having been Expert Lecturer from 1999 to 2003. He was Vice-Chair of
the Transmission, Access and Optical Systems Committee of the IEEE
Communications Society from 1999 to 2003, retaining the position of
Secretary from 2004. He is co-chair or vice-chair of a few symposia in IEEE
conferences (viz. ICC2004, GLOBECOM2005, ICC2006). He has been member of the
Technical Program Committees (TPC) of several IEEE conferences, including
ICC and GLOBECOM.
He served on ETSI and ITU-T
committees on digital network synchronization. He is author of the book
"Synchronization of Digital
Telecommunications Networks", John Wiley & Sons, Inc. [1]. He is
author or co-author of about twenty papers in this field, mostly published
on IEEE Conferences and Journals. |
Free
For
more information:
http://www.ieeeprc.org/bregni.HTM.
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Lecture Outline |
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The outline below is proposed
for a half-day lecture.
Introduction: synchronization processes in
telecommunications
The word
“synchronization” is used in several contexts in telecommunications,
addressing a wide spectrum of different timing issues. Carrier and symbol
synchronization, frame synchronization, bit synchronization, packet
synchronization, network synchronization, multimedia synchronization and
synchronization of real-time clocks are briefly reviewed.
Basic
concepts about timing of digital signals
• chronosignals
• timing relationships between
digital signals
• jitter and wander
Some
fundamental concepts and definitions about the timing of digital signals
(e.g., the definitions of synchronous, mesochronous, plesiochronous and
heterochronous digital signals) and about jitter and wander are introduced.
Timing
aspects in SDH/SONET networks
• Causes of jitter and wander in
a SDH/SONET transmission chain
• Synchronization processes
along a SDH transmission chain
• SDH/SONET synchronizer and
desynchronizer
• SDH/SONET pointer processor
This
section reviews the main causes of jitter and wander in a SDH/SONET
transmission chain: environmental conditions, digital signal regeneration,
overhead and stuffing bits in the mapping structures of tributaries into STM
frames, bit justification and – over all - pointer justification. Moreover,
the synchronizer, desynchronizer and pointer processor blocks are
introduced.
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