Computer Science Colloquium
UNUSUAL LOCATION on Tuesday 21/06/2011
Time : Tuesday 21/06/2011 14:30,
Place : Class 6 Taub Bld. NOTE UNUSUAL LOCATION
Speaker : Paul H. Siegel
Affiliation: Center for Magnetic Recording Research,
University of California, San Diego
Host : Ronny Roth
Title : Information Rates for Channels with Synchronization Errors.
The determination of information-theoretic limits and the design of
efficient codes for channels with synchronization errors are notoriously
difficult problems. An exploratory magnetic recording technology known as
bit-patterned media recording (BPMR) has renewed interest in these
challenges. In BPMR, the recording head must be accurately positioned over
the patterned magnetic islands to be written.
A number of factors can contribute to errors in this write process, for
example, frequency and phase drift in the write clock, irregularities in
the geometric configuration and shape of the patterned islands, and spread in
the switching field distribution within the population of islands. Another
consideration is the write span of the recording head, which introduces
memory into the write process.
We describe a write channel model for BPMR that reflects the occurrence of
data-dependent synchronization errors. The model accommodates
substitution-like errors as well as pairs of insertion-deletion errors
whose statistics are governed by an underlying channel state process.
We study several information-theoretic properties of this write-channel
model, including its capacity, symmetric information rate, first-order
Markov information rate, and zero-error capacity. Connections to models of
recording on conventional granular magnetic media are also drawn.
We then broaden the BPMR write-channel model to include a wider class of
synchronization error channels, including the deletion-duplication channel
and its special cases, the binary deletion channel and the so-called
"sticky" channel. For certain of these synchronization error channels, we
present simple, non-trivial and, occasionally, tight lower bounds on their
This is joint work with Aravind Iyengar and Jack K. Wolf.
Paul H. Siegel received the S.B. and Ph.D. degrees in mathematics from
the Massachusetts Institute of Technology (MIT), Cambridge, MA, in
1975 and 1979, respectively.
He held a Chaim Weizmann Postdoctoral Fellowship at the Courant
Institute, New York University. He was with the IBM Research Division
in San Jose, CA, from 1980 to 1995. He joined the faculty at the
University of California, San Diego in July 1995, where he is
currently Professor of Electrical and Computer Engineering in the
Jacobs School of Engineering. He is affiliated with the Center for
Magnetic Recording Research where he holds an endowed chair and served
as Director from 2000 to 2011. His primary research interests lie in
the areas of information theory and communications, particularly
coding and modulation techniques, with applications to digital data
storage and transmission.
Prof. Siegel was co-recipient, with R. Karabed, of the 1992 IEEE
Information Theory Society Paper Award and shared the 1993 IEEE
Communications Society Leonard G. Abraham Prize Paper Award with B.H.
Marcus and J.K. Wolf. With J.B. Soriaga and H.D. Pfister, he received
the 2007 Best Paper Award in Signal Processing and Coding for Data
Storage from the Data Storage Technical Committee of the IEEE
Communications Society. He holds several patents in the area of coding
and detection, and was named a Master Inventor at IBM Research in
1994. He is an IEEE Fellow and a member of the National Academy of
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Lecture starts at 14:30
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