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Channel and source coding for non-volatile flash memories

  • NAND flash memory is widely used for data storage due to low power consumption, high throughput, short random access latency, and high density. The storage density of the NAND flash memory devices increases from one generation to the next, albeit at the expense of storage reliability. Our objective in this dissertation is to improve the reliability of the NAND flash memory with a low hard implementation cost. We investigate the error characteristic, i.e. the various noises of the NAND flash memory. Based on the error behavior at different life-aging stages, we develop offset calibration techniques that minimize the bit error rate (BER). Furthermore, we introduce data compression to reduce the write amplification effect and support the error correction codes (ECC) unit. In the first scenario, the numerical results show that the data compression can reduce the wear-out by minimizing the amount of data that is written to the flash. In the ECC scenario, the compression gain is used to improve the ECC capability. Based on the first scenario, the write amplification effect can be halved for the considered target flash and data model. By combining the ECC and data compression, the NAND flash memory lifetime improves three fold compared with uncompressed data for the same data model. In order to improve the data reliability of the NAND flash memory, we investigate different ECC schemes based on concatenated codes like product codes, half-product codes, and generalized concatenated codes (GCC). We propose a construction for high-rate GCC for hard-input decoding. ECC based on soft-input decoding can significantly improve the reliability of NAND flash memories. Therefore, we propose a low-complexity soft-input decoding algorithm for high-rate GCC.

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Author:Mohammed RajabORCiD
Parent Title (German):Schriftenreihe der Institute für Systemdynamik (ISD) und optische Systeme (IOS)
Publisher:Springer Vieweg
Place of publication:Wiesbaden
Referee:Jürgen FreudenbergerORCiDGND, Antonia Wachter-Zeh
Advisor:Jürgen Freudenberger
Document Type:Doctoral Thesis
Year of Publication:2020
Granting Institution:Universität Ulm
Date of final exam:2019/07/26
Identifier:Im Katalog der Hochschule Konstanz ansehen
Release Date:2020/01/15
Page Number:XVI, 143
Volltextzugriff für Angehörige der Hochschule Konstanz möglich.
Institutes:Institut für Systemdynamik - ISD
DDC functional group:000 Allgemeines, Informatik, Informationswissenschaft
Relevance:Abgeschlossene Dissertation
Open Access?:Nein
Licence (German):License LogoUrheberrechtlich geschützt