NAND multi-level cell (MLC) flash memories are widely used due to low cost and high capacity. However, the increased number of levels in MLC results in larger interference and errors. The errors in MLC flash memories tend to be directional and limited-magnitude. Many related works focus on asymmetric errors, but bidirectional errors also occur because of the bidirectional interference and the adjustment of the hard-decision reference voltages. To take advantage of the characteristics, we propose t bidirectional (lu, ld) limited-magnitude error correction codes, which can reduce errors more effectively. The proposed code is systematic, and can correct t bidirectional errors with upward and downward magnitude of lu and ld, respectively. The proposed method is advantageous in that the parity size is reduced, and the error rate performance is better than conventional error correction codes when the code rate is equal.
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机译：由于低成本和高容量，NAND多级单元（MLC）闪存被广泛使用。但是，MLC中级别数量的增加会导致更大的干扰和错误。 MLC闪存中的错误往往是方向性的且幅度有限。许多相关的工作都集中在非对称误差上，但是由于双向干扰和硬决策参考电压的调整，也会出现双向误差。为了利用这些特性，我们提出了t双向（l u ，l d ）有限幅度纠错码，可以更有效地减少错误。所提出的代码是系统的，并且可以以向上和向下幅度分别为l u 和l d 校正t个双向误差。所提出的方法的优点在于，减小了奇偶校验大小，并且当码率相等时，差错率性能优于传统的纠错码。
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