Systems Seminar
Coding Approaches to Fault Tolerance in Dynamic Systems
Prof. Christoforos Hadjicostis
ECE Department
University of Illinois at Urbana-Champaign
Abstract
Fault tolerance has been a long standing necessity in system design
and operation. In systems with memory (state), however, modular
redundancy and other traditional approaches to fault tolerance are
undesirable not only because they are expensive but also because they
rely heavily on the assumption that the error-correcting (e.g. voting)
mechanism is fault-free. This talk presents a general framework that
systematically addresses these issues in fault-tolerant discrete-time
dynamic systems. Our approach replaces the original system with a
redundant implementation in which the state and next-state transition
mechanism of the original system are encoded. Error detection,
correction and/or reconfiguration are then based on detecting and
identifying violations on the state encoding of this redundant
implementation. One of the implications and advantages of this
approach is that, unlike traditional methodologies that rely on
concurrent checking at the end of each time step, this approach allows
the construction of redundant systems in which detection and
identification of errors is based on non-concurrent (e.g. periodic)
checks. In the resulting design, the checker can operate at a slower
speed than the rest of the system, which relaxes the stringent
requirements on its reliability. We demonstrate this approach in the
context of linear dynamic systems and arbitrary finite-state machines.
We also discuss how our framework can handle faults in the error
correction mechanism, enabling in this way the construction of
reliable systems exclusively from unreliable components. The talk
concludes with open problems and directions for future research.
Biography
Christoforos Hadjicostis received S.B. degrees in
Electrical Engineering, in Computer Science and Engineering, and in
Mathematics, the M.Eng. degree in Electrical Engineering and Computer
Science in 1995, and the Ph.D. degree in Electrical Engineering and
Computer Science in 1999, all from the Massachusetts Institute of
Technology, Cambridge, MA. In August 1999 he joined the Faculty at
the University of Illinois at Urbana-Champaign where he is currently
an Assistant Professor with the Department of Electrical and Computer
Engineering and a Research Assistant Professor with the Coordinated
Science Laboratory. Dr. Hadjicostis received the ECE Faculty
Outstanding Teaching Award in April 2003 and the Faculty Early
Development (CAREER) award from the National Science Foundation in
February 2001. As a graduate student, he served as president of the
MIT Chapter of HKN, received the Harold L. Hazen Teaching Award and
the Ernst A. Guillemin Thesis Prize, and received fellowships from the
National Semiconductor Corporation and the Grass Instrument Company.
Dr. Hadjicostis is a member of Eta Kappa Nu, Sigma Xi, and the IEEE.
Time and Place: Wed., Oct. 15, at 4:00 in 4610 Engr. Hall.
SYSTEMS SEMINAR WEB PAGE:
http://www.cae.wisc.edu/~gubner/seminar/