February 17, 2012, Arya Mazumdar, Massachusetts Institute of Technology
Friday, February 17, 2012 at 3:00 PM
8 St. Mary’s Street, Room 203
Refreshments served at 2:45.
Arya Mazumdar
Massachusetts Institute of Technology
Error-Correction Coding for Flash Memory: Rank Modulation
Reliability issues in memory and storage are playing an increasingly important role with the prospect of semiconductor (Flash) memory overtaking the hard-disk market and with the advent of new storage technologies such as phase-change memories. Flash memories are arrays of floating gate memory cells that are widely used in modern electronic devices. The reliability of the data stored in flash memory is affected by the drift in the electrical charge of the cells caused, for instance, by aging devices. A scheme called rank modulation, suitable for error protection in the data stored in flash memories, has been recently proposed. In this presentation we define the error-correcting codes required in the rank modulation scheme. We show that modelling these codes involve construction of packings of the space of permutations equipped with the Kendall-tau distance. We deduce the limits of reliable information storage in this scheme, as well as present several general constructions of codes for rank modulation. In particular, we obtain optimal rank modulation codes from conventional error-correcting codes of the Hamming space. Our codes afford near-linear time encoding and decoding algorithms. We end the presentation with a discussion of reliability issues of magnetic memory.
Arya Mazumdar is a postdoctoral scholar at the Massachusetts Institute of Technology (MIT). Before coming to MIT, he received the Ph.D. degree in Electrical and Computer Engineering from the University of Maryland, College Park, in 2011. He spent the summers of 2008 and 2010 at the Hewlett-Packard Laboratories, Palo Alto, CA, and IBM Almaden Research Center, San Jose, CA, respectively, as a research intern. Arya is a winner of the 2010 IEEE ISIT Student Paper Award. He is also the recipient of the Distinguished Dissertation Fellowship Award, 2011, at the University of Maryland. Arya’s research interests include information and coding theory, memory and storage, and signal processing.
Hosting Professor: Ari Trachtenberg
Student Host: Justin Foster