Gradual Channel Estimation Method for TLC NAND Flash Memory

As the storage density of NAND flash increases, the reliability is significantly degraded, making NAND flash memory more sensitive to noise. Among all noise sources, retention noise is a major one. Error correction based on channel parameter estimation is an essential method to deal with retention noise. In this paper, a time-saving channel parameter estimation method for TLC NAND flash memory is proposed. Proposed method reduces estimation time by three improvements: (1) reducing fitted parameters in one iteration step, (2) using pre-derived values as initial guess values to decrease iteration steps, (3) utilizing parallelism between data sensing operations and computation. Compared with previous work, proposed method estimates parameters with higher accuracy and lower time overhead which is verified by experiment results.