Title
Polar-coded forward error correction for MLC NAND flash memory.
Abstract
With the ever-growing storage density, high-speed, and low-cost data access, flash memory has inevitably become popular. Multi-level cell (MLC) NAND flash memory, which can well balance the data density and memory stability, has occupied the largest market share of flash memory. With the aggressive memory scaling, however, the reliability decays sharply owing to multiple interferences. Therefore, the control system should be embedded with a suitable error correction code (ECC) to guarantee the data integrity and accuracy. We proposed the pre-check scheme which is a multi-strategy polar code scheme to strike a balance between reasonable frame error rate (FER) and decoding latency. Three decoders namely binary-input, quantized-soft, and pure-soft decoders are embedded in this scheme. Since the calculation of soft log-likelihood ratio (LLR) inputs needs multiple sensing operations and optional quantization boundaries, a 2-bit quantized hard-decision decoder is proposed to outperform the hard-decoded LDPC bit-flipping decoder with fewer sensing operations. We notice that polar codes have much lower computational complexity compared with LDPC codes. The stepwise maximum mutual information (SMMI) scheme is also proposed to obtain overlapped boundaries without exhausting search. The mapping scheme using Gray code is employed and proved to achieve better raw error performance compared with other alternatives. Hardware architectures are also given in this paper.
Year
DOI
Venue
2018
10.1007/s11432-017-9394-y
SCIENCE CHINA Information Sciences
Keywords
Field
DocType
polar coding, non-volatile memory, error correcting code, NAND, flash memory
Forward error correction,Flash memory,Low-density parity-check code,Control theory,Algorithm,Gray code,Error detection and correction,Non-volatile memory,Polar code,Quantization (signal processing),Mathematics
Journal
Volume
Issue
ISSN
61
10
1674-733X
Citations 
PageRank 
References 
0
0.34
22
Authors
7
Name
Order
Citations
PageRank
Haochuan Song100.34
Jen-Chien Fu200.34
Shih-Jia Zeng300.34
Jin Sha4225.93
Zaichen Zhang513420.67
xiaohu you62529272.49
Chuan Zhang710013.67