Apple Inc.

Tomer Ish-Shalom

Moti Teitel

Ronen Dar

Eyal Gurgi

Micha Anholt

Yonathan Tate

Barak Baum

Asaf Landau

Yoav Kasorla

Yael Shur

Alex Radinski

A decoder includes multiple variable-node circuits and logic circuitry. The variable-node circuits hold variables of an Error Correction Code (ECC), defined by a set of check equations over multiple variables corresponding to the variable-node circuits. The logic circuitry is configured to receive a code word encoded using the ECC, to hold, prior to decoding in a sequence of iterations, a scheduling scheme that specifies, for each iteration, whether each of the variable-node circuits is to be processed or skipped in that iteration, to perform the iterations in the sequence, including selecting for processing, in each iteration, only variable-node circuits specified for processing in that iteration, to determine for each selected variable-node circuit, a count of unsatisfied check equations in which the respective variable participates, and to make a decision on flipping a binary value of the variable based on the count and apply the decision by the respective variable-node circuit.

Efficient LDPC decoding with predefined iteration-dependent scheduling scheme

A memory system includes an interface and storage circuitry. The interface is configured to communicate with a plurality of memory cells that store data by setting the memory cells to analog voltages representative of respective storage values. The storage circuitry is configured to read from a group of the memory cells a code word encoded using an Error Correction Code (ECC), by sensing the memory cells using at least first and second read thresholds for producing respective first and second readouts, to calculate, based on at least one of the first and second readouts, (i) a syndrome weight that is indicative of an actual number of errors contained in the code word, and (ii) a mid-zone count of the memory cells for which the first readout differs from the second readout, and, to evaluate a performance measure for the memory cells, based on the calculated syndrome weight and mid-zone count.

Syndrome weight based evaluation of memory cells performance using multiple sense operations

A method for data encoding includes receiving a data vector to be encoded into a code word in accordance with a code defined by a parity-check matrix H. An intermediate vectoris produced by multiplying the data vector by a data sub-matrix Hof the parity-check matrix H. A parity part of the code word is derived by applying a sequence of operations to the intermediate vectorbased on a decomposition of a parity sub-matrix Hof the matrix H using matrices A, C, U and V, in which decomposition A is a block triangular matrix that has the same size as H, C is matrix that is smaller than H, and the matrices U and V are placement matrices that are selected so that A, C, U and V satisfy a matrix equation H=A+UCV.

Data encoding by efficient inversion of a parity-check sub-matrix

An apparatus includes an interface, main and secondary processing modules, and circuitry. The interface is configured to receive input data to be processed in accordance with a GLDPC code defined by a parity-check-matrix including multiple sub-matrices, each sub-matrix including a main diagonal and one or more secondary diagonals, and each of the main and secondary diagonals includes N respective block matrices. The main processing module is configured to calculate N first partial syndromes based on the input data and on the block matrices of the main diagonals. The secondary processing module is configured to calculate N second partial syndromes based on the input data and on the block matrices of the secondary diagonals. The circuitry is configured to produce N syndromes by respectively combining the N first partial syndromes with the N second partial syndromes, and to encode or decode the input data, based on the N syndromes.

Efficient syndrome calculation in processing a GLDPC code

A storage device includes a memory that includes storage circuitry and a memory including multiple memory cells. The storage circuitry is configured to store in a group of the memory cells data that was encoded using an error correcting code (ECC) consisting of multiple component codes, to define multiple threshold settings, each specifying positions of one or more reading-thresholds, to read the data from the memory cells in the group using the threshold settings and decode the read data using the component codes, to calculate for the component codes respective component-code scores that are indicative of levels of confidence in the decoded data of the component-codes, to select, based on the component-code scores, a threshold setting that is expected to result in a best readout performance among the multiple threshold settings, and to read data from the memory using the selected threshold setting.

Reading-threshold setting based on data encoded with a multi-component code

An apparatus for data coding includes an encoder and a decoder. The encoder is configured to receive input data including one or more m-bit data groups that are associated with respective group indices, to generate a code word that includes the input data and an m-bit redundancy that depends on the data groups and on the respective group indices, and to send the code word over a channel. The decoder is connected to the channel and is configured to produce a syndrome that equals zero when the code word is error-free, and when the code word contains a single error caused by the channel, is indicative of an erroneous group in which the single error occurred, and of a location of the single error within the erroneous group, and to recover the input data by correcting the single error at the location in the erroneous group.

Efficient coding with single-error correction and double-error detection capabilities

A decoder includes variable-node circuitry, check-node circuitry and a Message Passing (MP) module, which includes multiple configurable partial cyclic shifters that each supports only a partial subset of shift values out of a full range of shift values. . . L&#x2212;1. The variable-node circuitry and check-node circuitry are configured to exchange messages with one another in accordance with a parity check matrix that represents a respective Quasi-Cyclic (QC)-Low Density Parity Check (LDPC) Error Correcting Code (ECC) and that includes L-by-L sub-matrices, and to process the exchanged messages to decode a given code word that was encoded using the QC-LDPC ECC. The MP module is configured to schedule the variable-node circuitry and check-node circuitry that are interconnected in accordance with a respective sub-matrix to exchange L messages simultaneously by assigning a given partial cyclic shifter to shift the L messages cyclically a number of positions that depends on a structure of the respective sub-matrix.

LDPC decoder with efficient circular shifters

A method for Error Correction Code (ECC) encoding includes receiving data to be encoded. The data is encoded to produce a composite code word that includes multiple component code words. Each component code word in at least a subset of the component code words is encoded in accordance with a respective component code and has at least one respective bit in common with each of the other component code words.

Error correction coding with high-degree overlap among component codes

A method for data storage includes reading storage values, which represent stored data, from a group of memory cells using read thresholds, and deriving respective soft reliability metrics for the storage values. The storage values are classified into two or more subgroups based on a predefined classification criterion. Independently within each subgroup, a subgroup-specific distribution of the storage values in the subgroup is estimated, and the soft reliability metrics of the storage values in the subgroup are corrected based on the subgroup-specific distribution. The stored data is decoded using the corrected soft reliability metrics.

Correcting soft reliability measures of storage values read from memory cells

A method includes decoding a code word of an Error Correction Code (ECC), which is representable by a set of check equations, by performing a sequence of iterations, such that each iteration involves processing of multiple variable nodes. For one or more selected variable nodes, a count of the check equations that are defined over one or more variables held respectively by the one or more selected variable nodes is evaluated, and, when the count meets a predefined skipping criterion, the one or more selected variable nodes are omitted from a given iteration in the sequence.

Decoder with selective iteration scheduling

An apparatus includes a memory and storage circuitry. The storage circuitry is configured to receive at least one request causing execution of a sequence of memory commands in the memory, to identify that, although a first memory command appears in the sequence before a second memory command, the execution of the second memory command would improve a performance of the execution of the first memory command, and to execute the second memory command and then to execute the first memory command with the improved execution performance.

Command order re-sequencing in non-volatile memory

A method for decoding includes receiving channel inputs for respective bits of a super code word that includes at least first and second component code words having a shared group of bits. At least the first and second component code words are iteratively decoded, and, in response to recognizing that the first and second component code words contain errors only within the shared group of bits, the first and second component code words are jointly decoded.

Decoding a super-code using joint decoding of underlying component codes

A method includes programming a group of analog memory cells by writing respective analog values into the memory cells in the group. After programming the group, the analog values are read from the memory cells in the group using a set of read thresholds so as to produce readout results. Respective optimal positions for the read thresholds in the set are identified based on the readout results. A noise level in the readout results is estimated based on the identified optimal positions of the read thresholds.

SNR estimation in analog memory cells

A method includes storing data in a group of analog memory cells by writing respective analog values into the memory cells in the group. After storing the data, the analog values are read from the memory cells in the group one or more times using one or more respective read thresholds so as to produce readout results. Reliability measures are computed for the read analog values based on the readout results. An offset of the one or more read thresholds from an optimal read threshold position is estimated based on the reliability measures. The reliability measures are modified to compensate for the estimated offset, and the data stored in the analog memory cells in the group is decoded using the corrected reliability measures.

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