Reliability-Based ECC System for Adaptive Protection of NAND Flash Memories

Abstract

In order to make the implementation of the error correcting code(ECC) efficiently, it should be tailored individually to each block, and can be changed over time as the running condition changes. The combined effect of reliability factors makes it difficult to select ECC by considering the effect factors separately. So more appropriate ECC selection method need to be found. Meanwhile, most of the ECCs are designed to adapt to specific hardware, the implementation of the ECC needs to be redesigned when the hardware platform changes. So the introduction of commonly used ECC system can provide a great convenience for error correction. In this paper, we propose an easy-to-use and flexible ECC system which takes advantage of the reliability map to provide adaptive protection. Proposed ECC system comprises ECC selection module and ECC codec module. A method to select appropriate ECC based on reliability map which provides the evaluation of bit error rate is proposed in ECC selection module. ECC encoder and decoder suit are called in ECC codec module to provide various protection. Proposed system can be used in many platforms, such as DSP, ARM, etc. Compared with the early works, the uncorrectable bit error rate(UBER) performance, coding time and redundancy are all optimized by proposed ECC system.