Introduction

Advanced Low-Density Parity-Check (LDPC) codes are powerful error-correction algorithms essential for maintaining data integrity in high-performance storage and communication systems. They use sparse parity-check matrices to detect and locate errors, which are then corrected iteratively through belief propagation, enabling reliable data recovery even under challenging conditions.

LDPC Decoding Strategy

SP Industrial LDPC decoding strategies are essential for error correction in NAND flash memory and other storage or communication systems. The goal is to recover the original data from potentially corrupted input using a series of decoding techniques.

1. Hard decoding is the initial attempt, based on hard bits—values interpreted directly as 0 or 1 from the read signal without ambiguity. The LDPC decoder uses only these binary values to correct errors. This method is fast and power-efficient but less reliable when the raw bit error rate (RBER) is high. Hard decoding is typically the first step in the process, and if it succeeds, no further action is required.
2. Read Retry: If hard decoding fails, the controller initiates read retry, a technique that adjusts the read threshold voltages to reinterpret the stored data more accurately. This is necessary because NAND cells may experience voltage shifts due to program/erase cycles, data retention loss, or read disturb effects. By retrying reads at different reference voltages, the controller can lower the RBER and produce more reliable input for the next stage.
3. Soft decoding is an advanced method that uses soft bits—values that represent confidence levels rather than absolute binary values. The controller performs multiple reads at varying threshold voltages to collect more detailed signal information. This data is translated into soft information for the LDPC decoder, which then runs iterative algorithms to correct errors. Soft decoding is used only if hard decoding and read retry are unsuccessful. Although it is more computationally intensive, soft decoding offers significantly higher accuracy, especially when dealing with degraded or heavily worn NAND cells.

SP Industrial LDPC decoding strategies deliver a high-reliability, adaptive error correction architecture, optimized to recover data accurately in high-error-rate scenarios such as read disturb, retention loss, and program/erase cycling in NAND flash memory.