DMMC: A Polar Code Construction Method for Improving Performance in TLC NAND Flash

Abstract

3D TLC NAND flash memory significantly increases the storage capacity but makes data more prone to errors. To address the reliability problem, Polar Code is one coding method that can reach the channel capacity1. However, the 3D NAND flash memory channel is uncertain due to the variation of retention time and program/erase(P/E) cycle. So it is difficult to construct Polar Code in NAND flash memory. This paper proposes a new Polar Code construction method called Dynamic Merge Monte Carlo(DMMC). DMMC uses the Monte Carlo method to obtain the optimal Polar Code construction and then reduces the space overhead by combining similar construction so that it can be used in flash memory systems. Compared with the conventional method, the uncorrectable bit error rate(UBER) of the proposed method can reduce by up to 90.5%, and the read latency can reduce by more than 50%.