Toronto
Networking Seminar 2006
Probabilistic
Network Calculus:
A System Theory for the Internet
Markus
Fidler
University of Toronto
Date:
January 20, 3pm
Location: 1210 Bahen Center
Abstract
The
exact performance evaluation of communication systems enables network
operators to dimension capacities and buffers to implement
costefficient services with defined loss rates and endtoend delays.
Respective quality of service parameters are crucial for realtime
applications, such as Internet telephony or video broadcasting.
Classical queuing theory has been widely used to derive such
performance measures for telecommunication systems. The applied Poisson
processes are, however, not well suited to model Internet traffic. This
shortcoming has motivated the development of new approaches, such as
the theory of effective bandwidths and network calculus.
Network calculus is a minplus systemtheory for worstcase analysis of
backlogs and delays. It features intuitive and powerful convolution
formulas for analysis of single servers and for concatenation of tandem
servers. This concatenation property is of highest importance since it
establishes a general framework for efficient analysis of multiple node
scenarios. Recent research loosens the worstcase assumptions of
network calculus to evolve a probabilistic equivalent that benefits
from statistical multiplexing of independent flows. Significant
achievements have already been made, owing for example to the theory of
effective bandwidths, however, the outstanding endtoend scalability
set up by deterministic network calculus has not been attained.
This presentation introduces a concise probabilistic network calculus
which effectively builds on moment generating functions. The developed
theory features endtoend probabilistic performance bounds which scale
remarkably good, both in the number of traversed nodes as well as in
the number of aggregated flows.
Bio:
Markus
Fidler is currently an Emmy Noether fellow of the German Research
Foundation (DFG) and a postdoctoral fellow of the University of
Toronto. He received his Dipl.Ing. in electrical engineering from RWTH
Aachen University in 1997, Dipl.Kfm. in business economics from Hagen
University in 2001, and Dr.Ing. from RWTH Aachen University in 2003.
Before he joined the department of computer science at Aachen
University in 2001 he was employed in 1997 by Hagenuk Telecom and later
by Alcatel R&D, where he worked on GSM Phase 2 and GPRS. In the
fall 2004 he was a postdoctoral fellow of the MittagLeffler institute,
Sweden, and during the year 2005 at the Centre for Quantifiable Quality
of Service at NTNU Trondheim, Norway. His current research interests
are in the field of probabilistic network calculus.
