[color-box color=”yellow”] Modeling, Coding, and Data Coding Theoretic and Combinatorial Methods for Next-Generation Storage Systems and Memories
Advanced graph based and algebraic codes for ultra dense non-volatile memories
Advanced graph based coding methods for future HDDs
Asymmetric coding for Flash
Erasure coding for on chip memories
Channel modeling and analysis
New data representation schemes [/color-box]
Overview: All modern data storage systems and memories require increasingly high levels of reliability. While channel coding methods have been a reliable workhorse since the early days of computer storage, conventional techniques are no longer appropriate in the context of new applications: traditional methods are almost universally designed to optimize for the Hamming metric, yet modern memories and storage exhibit a very high levels of asymmetry and non-uniformity. Using symmetric error correcting codes in such applications is not only mathematically suboptimal but also wasteful of precious system resources.
Recent results: In our work, we deliberately depart from optimizing for the Hamming metric and focus on code designs that are attuned to the physical characteristics of the underlying devices. We explore a variety of innovative code construction techniques, by combining tools from combinatorial graph theory, convex optimization, and abstract algebra. Our rich code repertoire includes many state of the art constructions for an array of different applications.
Additionally, we offer system level perspectives of our mathematical solutions for a broad spectrum of applications, from on-chip memories to Flash to magnetic recording.
Current research is on the development of novel methods of asymmetric coding for NVMs and multidimensional codes for ultra dense storage.
Our group has a distinguished record of research contributions in this domain.
Representative recent publications include both review articles and original contributions:
- L. Dolecek and F. Sala, “Channel Coding Methods for Non-Volatile Memories,” Foundations and Trends in Communications and Information Theory, Vol. 13 (1), pp. 1- 136, February 2016.
- F. Sala, C. Schoeny, and L. Dolecek, “Advanced Algebraic and Graph-Based ECC Schemes for Flash Memories,” to appear in 3-D Flash Memories, Ed. Rino Micheloni, Springer, 2016.
- F. Sala, K. A. S. Immink, and L. Dolecek, “Error Control Schemes for Modern Flash Memories: Solutions for Flash Deficiencies,” IEEE Consumer Electronics, vol. 4 (1), pp. 66-73, Jan. 2015.
- L. Dolecek, M. Blaum, S. Bruck, A. Jiang, K. Ramchandran, and B. Vasic, “Guest Editorial: Communication Methodologies for the Next Generation Data Storage Systems,” IEEE Journal on Selected Areas in Communications, vol. 32 (5), pp. 825- 830, May 2014.
Graph-based codes for Flash and HDDs.
- A. Hareedy, C. Lanka, C. Schoeny, and L. Dolecek, “The Weight Consistency Matrix Framework for General Non-Binary LDPC Code Optimization: Applications in Flash Memories,” Proc. IEEE International Symposium on Information Theory (ISIT), Barcelona, Spain, July 2016.
- A. Hareedy, B. Amiri, R. Galbraith, and L. Dolecek, “Non-Binary LDPC Codes for Magnetic Recording Channels: Error Floor Analysis and Optimized Code Design”, submitted 2015.
- A. Hareedy, B. Amiri, S. Zhao, R. Galbraith, and L. Dolecek, “Non-Binary LDPC Code Optimization for Partial Response Channels,” in Proc. IEEE Globecom, Dec. 2015. Best paper award.
Algebraic Codes and Signal Processing for NVMs.
- R. Gabrys, E. Yaakobi, F. Farnoud, F. Sala, S. Bruck, and L. Dolecek, “Codes Correcting Erasures and Deletions for Rank Modulation“, IEEE Transactions on Information Theory, vol. 62 (1), pp. 136 — 150, January 2016.
- F. Sala, C. Schoeny, D, Divsalar, and L. Dolecek, “Asymmetric ECCs for Flash in High Radiation Environments,” IEEE Asilomar Conference on Signals, Systems and Computers, Monterey, CA, Nov. 2015 (invited).
- C. Schoeny, F. Sala, and L. Dolecek, “Analysis and Coding Schemes for the Flash Normal-Laplace Mixture Channel,” in Proc. IEEE International Symposium on Information Theory (ISIT), Hong Kong, June, 2015.
- R. Gabrys, E. Yaakobi, and L. Dolecek, “Correcting Grain-Errors in Magnetic Media,” IEEE Transactions on Information Theory, vol. 61 (5), pp.2256 — 2272, May 2015.
- R. Gabrys and L. Dolecek, “Constructions of Non-binary WOM Codes for Multilevel Flash Memories,” IEEE Transactions on Information Theory, vol. 61 (4), pp. 1905-1919, April 2015.
- R. Gabrys, F. Sala, and L. Dolecek, “Coding for Unreliable Flash Memory Cells,” IEEE Communication Letters, vol 18 (9), pp. 1491 — 1494, July 2014.
- R. Gabrys, E. Yaakobi and L. Dolecek, “Graded bit error correcting codes with applications to flash memory,” IEEE Transactions on Information Theory, vol. 59(4), pp. 2315 — 2327, Apr. 2013.
- F. Sala, R. Gabrys and L. Dolecek, “Dynamic threshold schemes for multi-level non-volatile memories,” IEEE Transactions on Communications, vol. 61 (7), pp. 2624 – 2634, Jul. 2013.
Coding for on-chip memories.
- F. Sala, H. Duwe, L. Dolecek, and R. Kumar, “A Unified Framework for Error Correction Techniques in On-Chip Memories,” SELSE Workshop and DSN Conference, 2016. Best of Selse Award.