Patent ID: 11966587
Assignee: FUZHOU UNIVERSITY
Field: Computer technology (Electrical engineering)
Classification: CPC G  Y | IPC G

Claim 1:
2. The method for optimizing a Polar-RNNA quantizer of MLC NAND flash memory based on deep learning according to claim 1, wherein Step S1 specifically comprises:
devoting a read-back voltage of a kth memory cell of the MLC flash by Vk, inputting v={v1, v2, . . . , vL} to the neural network, and setting L as the number of neurons of an input layer, and outputting a soft estimation {tilde over (x)} ={{tilde over (x)}1, {tilde over (x)}2, . . . , {tilde over (x)}L} of a tag x by the neural network;
as for the MLC flash, expressing {11,10,00,01} by a tag {0,1,2,3}, so that a hard estimation {circumflex over (X)}k ∈{0,1,2,3} of the kth memory cell xk ∈{0,1,2,3} is obtained by acquiring integers {tilde over (X)}k most approximate to {tilde over (x)} output by the neural network; then, obtaining a corresponding memory cell symbol through a mapping {0,1,2,3}→{11,10,00,01};
setting a set of read thresholds {R1, R2, R3} for a read-back voltage {right arrow over (v)} of a given set of memory cells to obtain a hard estimation of the memory cell symbol, which is denoted by {tilde over (x)}; inputting {right arrow over (v)} to an RNN detector to obtain a hard estimation {circumflex over (X)} of a storage symbol based on a principle of proximity;
setting, during a search process, N RNN output sequences with a length of L, and denoting an ith RNN output sequence as {circumflex over (X)}1, so that {circumflex over (X)}={{circumflex over (x)}1, {circumflex over (x)}2, . . . , {circumflex over (x)}N}, and X={x1, x2, . . . , xN};
wherein, a formula for calculating optimal thresholds {R*1, R*2, R*3} is:, {
      
       
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uniformly quantizing a search space into m interval boundaries {B0, B1, . . . , Bm}, wherein B0=−∞<B1=Vs11<. . . <Bm-1 =Vs01 <Bm=∞; and
searching out the optimal thresholds {R*1, R*2, R*3} from {B1, B2, . . . , Bm-1} through an exhaustive search method to minimize a Hamming distance between two outputs.