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Improving Nonvolatile Memories by Coding over Permutations

Event Date: April 8, 2014
Speaker: Moshe Schwartz
Speaker Affiliation: Ben-Gurion University, Negev, Israel
Sponsor: Prospective ECE faculty member.
Time: 2:00pm
Location: MSEE 239
Contact Name: Professor Chih-Chun Wang
Contact Phone: 765-494-5568
Contact Email:

Nonvolatile memories, e.g., flash memories, are quickly replacing magnetic mass-storage devices. Smaller cells, high-density layouts, and multi-level technology, all improve storage density, but at the cost of reliability. It was recently suggested that replacing the multi-level technology with a rank-modulation scheme can mitigate some of the adverse effects associated with high storage density. In the rank-modulation scheme, cells are not read individually. Instead, cells are grouped together, compared against each other, and the information read (and stored) is a permutation. Thus, in order to work with the rank-modulation schemes, error-correcting codes over permutations are required. The talk will focus on this scheme, describe some code constructions, manipulation of codes, and various related problems, such as enumeration of permutations in a ball, which has applications in compression of permutations, and noisy sorting.

Moshe Schwartz received the B.A., M.Sc., and Ph.D. degrees from the Technion - Israel Institute of Technology, Haifa, Israel, in 1997, 1998, and 2004 respectively, all from the Computer Science Department. He was a Fulbright post-doctoral researcher in the Department of Electrical and Computer Engineering, University of California San Diego, and a post-doctoral researcher in the Department of Electrical Engineering, California Institute of Technology. He now holds a position with the Department of Electrical and Computer Engineering, Ben-Gurion University of the Negev, Israel. He is currently on a sabbatical as a visiting scientist in the Research Laboratory of Electronics, MIT, in Cambridge, MA. He received the 2009 IEEE Communications Society Best Paper Award in Signal Processing and Coding for Data Storage, and the 2010 IEEE Communications Society Best Student Paper Award in Signal Processing and Coding for Data Storage. His research interests include algebraic coding, combinatorial structures, and digital sequences.