Pragmatic concatenated codes for NAND flash memory = NAND 플래쉬 메모리를 위한 실용적 연접 부호

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Two concatenated coding schemes based on fixed-rate Raptor codes are proposed for error control in NAND flash memory. One is geared for off-line recovery of uncorrectable pages and the other is designed for page error correction during the normal read mode. Both proposed coding strategies assume hard-decision decoding of the inner code with inner decoding failure generating erasure symbols for the outer Raptor code. Raptor codes allow low-complexity decoding of very long codewords while providing capacity- approaching performance for erasure channels. For the off-line page recovery scheme, one whole NAND block forms a Raptor codeword with each inner codeword typically made up of several Raptor symbols. An efficient look-up-table strategy is devised for Raptor encoding and decoding which avoids using large buffers in the controller despite the substantial size of the Raptor code employed. The potential performance benefit of the proposed scheme is evaluated in terms of the probability of block recovery conditioned on the presence of uncorrectable pages. In the suggested page-error-correction strategy, on the other hand, a hard-decision-iterating product code is used as the inner code. The specific product code employed in this work is based on row-column concatenation with multiple intersecting bits allowing the use of longer component codes. In this setting the collection of bits captured within each intersection of the row-column codes acts as the Raptor symbol(s), and the intersections of failed row codes and column codes are declared as erasures. The error rate analysis indicates that the proposed concatenation provides a considerable performance boost relative to the existing error correcting system based on long Bose-Chaudhuri-Hocquenghem (BCH) codes.
Advisors
Moon, Jae-Kyunresearcher문재균Lee, Yong-Hoon이용훈
Description
한국과학기술원 : 전기및전자공학과,
Publisher
한국과학기술원
Issue Date
2014
Identifier
568580/325007  / 020095096
Language
eng
Description

학위논문(박사) - 한국과학기술원 : 전기및전자공학과, 2014.2, [ vii, 65 p. ]

Keywords

NAND 플래쉬 메모리 시스템; 연접 부호; Raptor 부호; LDPC 부호; 블록 복구; 오류 정정 부호; Concatenated codes; NAND flash memory systems; Error control codes; Raptor codes; LDPC codes; Block recovery

URI
http://hdl.handle.net/10203/196544
Link
http://library.kaist.ac.kr/search/detail/view.do?bibCtrlNo=568580&flag=dissertation
Appears in Collection
EE-Theses_Ph.D.(박사논문)
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