Low-density parity-check (LDPC) codes can be used to improve the storage reliability of multi-level cell (MLC) flash memories because of their strong error-correcting capability. In order to improve the weighted bit-flipping (WBF) decoding of LDPC codes in MLC flash memories with cell-to-cell interference (CCI), we propose two strategies of normalizing weights and adjusting log-likelihood ratio (LLR) values. Simulation results show that the WBF decoding under the proposed strategies is much advantageous in both error and convergence performances over existing WBF decoding algorithms. Based on complexity analysis, the strategies provide the WBF decoding with a good tradeoff between performance and complexity.

In this paper, a weighted multiple bit flipping (WMBF) algorithman for decoding low-density parity-check (LDPC) codes is proposed first. Then the improved WMBF algorithm which we call the efficient weighted bit-flipping (EWBF) algorithm is developed. The EWBF algorithm can dynamically choose either multiple bit-flipping or single bit-flipping in each iteration according to the log-likelihood ratio of the error probability of the received bits. Thus, it can efficiently increase the convergence speed of decoding and prevent the decoding process from falling into loop traps. Compared with the parallel weighted bit-flipping (PWBF) algorithm, the EWBF algorithm can achieve significantly lower computational complexity without performance degradation when the Euclidean geometry (EG)-LDPC codes are decoded. Furthermore, the flipping criterion does not require any parameter adjustment.