Performance Comparison of Multi-Level Coding Schemes for Flash Memory

This paper compares performances of a number of multi-level coding (MLC)lmulti-stage decoding (MSD) schemes for NAND flash memory applications. A considered scheme is the MLC/MSD method of Imai and Hirakawa applied to l-dimensional (I-D) and 2-D constellations with Bose-Chaudhuri-Hocquemghem (BCH) component codes. By applying MLC/MSD techniques, it is possible to minimize the code rate loss caused by using the code designed for the bit level of page with the highest error rate equally to the remaining bit level of pages. The analytical error rate results indicate performance advantages of MLC/MSD schemes relative to the baseline BCH coding method.