Parameterized iterative message passing decoder

A machine-implemented method comprising:

• passing a batch of noisy versions of codewords through a parameterized iterative message passing decoder, including performing message passing computations comprising parameters;
• revising the parameters based on mutual information between a-posteriori log likelihood ratios (LLRs) of passing the batch of noisy codewords through the parameterized iterative message passing decoder and clean versions of the codewords, including revising the parameters based on how much the mutual information would change with respect to a change in the parameters for each noisy codeword;
• repeating the passing and the revising with additional batches of noisy versions of codewords until the parameters are learned;
• accessing encoded data that was stored in non-volatile memory;
• and
• decoding the encoded data using the revised parameters in the parameterized iterative message passing decoder.

A non-volatile storage device, comprising:

• non-volatile storage cells;
• means for performing message passing computations on a batch of noisy versions of codewords over one or more iterations of a sparse bipartite graph to generate a-posteriori log-likelihood ratios (LLRs), wherein ones of the message passing computations have one or more parameters, wherein the message passing computations comprise messages between bit nodes and check nodes in the sparse bipartite graph;
• means for revising the one or more parameters based on mutual information between the a-posteriori LLRs and clean versions of the codewords, including means for revising the one or more parameters based on a gradient of ones of the parameters with respect to the mutual information;
• means for revising the one or more parameters based on performing the message passing computations on additional batches of noisy versions of codewords over one or more iterations of the sparse bipartite graph to generate a-posteriori log-likelihood ratios (LLRs) and revising the one or more parameters based on the mutual information between the a-posteriori LLRs and clean versions of the codewords with each batch;
• and
• means for accessing encoded data from the non-volatile storage cells;
• wherein the means for performing message passing computations on a batch of noisy versions of codewords is further for decoding the encoded data by performing the message passing computations with the revised one or more parameters over one or more iterations of the sparse bipartite graph.