Abstract: Disclosed are devices, systems and methods for improving fast fail support for error correction in non-volatile memory. An exemplary method includes (a) receiving a codeword from a read operation in a fast fail mode, (b) initially configuring a maximum number of iterations (Nmax) and a set of values for a plurality of bit flipping thresholds for performing a decoding operation on the codeword, (c) performing a plurality of decoding iterations (N), each iteration using a subset of bit flipping thresholds, (d) calculating a remaining number of iterations (Nrem) as a difference between Nmax and N, (e) reconfiguring, based on Nrem and a latency requirement of the read operation in the fast fail mode, the set of values for the plurality of bit flipping thresholds to restart the decoding operation, and (f) repeating operations (c) through (e) until the codeword is successfully decoded or Nrem is less than or equal to 0.

Abstract: Embodiments describe a method for reading data from storage that includes selecting a block of memory to read, identifying a read retry table for reading the block, determining that the read retry table for the selected block of memory needs to be updated, and reading the block of memory using a new set of read threshold voltages from the read retry table. Responsive to a successful read operation using the new set of voltages, the method can also include replacing the initial set of read voltages in the first field with the new set of read voltages, and filling the plurality of subsequent fields in the read retry table with additional sets of read threshold voltages identified from a read retry neighbor table, where at least one of the additional sets of read voltages is closest in distance to the initial set of read voltages in read voltage space.

Abstract: Techniques related to improving a performance related to at least data reads from a memory are described. In an example, data is stored in a block of the memory as codewords. A data read includes a determination of whether each bit from a portion of the block is a zero or a one based on voltage measurements. Prior to decoding the codewords by performing a decoding procedure by an ECC decoder of the memory, a first number of errors “E01” and a second number of errors “E10” are estimated, where the first number of errors “E01” is associated with bits each being a true zero and erroneously determined as a one, and where the second number of errors “E10” associated with bits each being a true one and erroneously determined as a zero. Thereafter, the decoding of the codewords based on the decoding procedure is performed.

Abstract: Techniques are described for improving the decoding latency and throughput of an error correction system that includes a bit flipping (BF) decoder, where the BF decoder uses a bit flipping procedure. In an example, different decoding parameters are determined including any of a decoding number of a decoding iteration, a checksum of a codeword, a degree of a variable node, and a bit flipping threshold defined for the bit flipping procedure. Based on one or more of these decoding parameters, a decision can be generated to skip the bit flipping decoding procedure, thereby decreasing the decoding latency and increasing the decoding throughput. Otherwise, the bit flipping decoding procedure can be performed to compute a bit flipping energy and determine whether particular bits are to be flipped or not. Hence, the overall performance (e.g., bit error rate) is not significantly impacted.

Abstract: A memory controller optimizes read threshold values for a memory device using multi-dimensional search. The controller performs a read operation on cells using a pair of default read threshold values on a multi-dimensional plane. When the read operation has failed, the controller determines program states of cells and a pair of next read threshold values based on the program states and performs an additional read operation using the next read threshold values.

Abstract: Techniques are described for improving the decoding latency and throughput of an error correction system that includes a bit flipping (BF) decoder, where the BF decoder uses a bit flipping procedure. In an example, different decoding parameters are determined including any of a decoding number of a decoding iteration, a checksum of a codeword, a degree of a variable node, and a bit flipping threshold defined for the bit flipping procedure. Based on one or more of these decoding parameters, a decision can be generated to skip the bit flipping decoding procedure, thereby decreasing the decoding latency and increasing the decoding throughput. Otherwise, the bit flipping decoding procedure can be performed to compute a bit flipping energy and determine whether particular bits are to be flipped or not. Hence, the overall performance (e.g., bit error rate) is not significantly impacted.

Abstract: Multiple memory systems with respective decoders employ a low latency implementation of a read recovery level feature in decoding data. The decoding comprises receiving from a host a read request for decoding read data at a first recovery level by a first memory system, a first decoder of the first memory system being set at a second recovery level with a corresponding maximum iteration number when the read request is received by the first memory system; and operating the first decoder, after a set time elapses, to decode the read data at the second recovery level. A second decoder of a second memory system is set at the first recovery level for at least part of the time during which the first decoder operates to decode the read data at the second recovery level.

Abstract: Devices, systems and methods for reducing complexity of a bit-flipping decoder for quasi-cyclic (QC) low-density parity-check (LDPC) codes are described. An example method includes receiving a noisy codeword that is based on a transmitted codeword generated from an irregular QC-LDPC code, the irregular QC-LDPC code having an associated parity matrix, storing, based on a weight of a plurality of columns of the parity matrix of the irregular QC-LDPC code, a portion of the noisy codeword corresponding to the plurality of columns in a first buffer of a plurality of buffers, and accessing and processing the portion of the noisy codeword that includes applying a vertically shuffled scheduling (VSS) scheme that uses a plurality of processing units to determine a candidate version of a portion of the transmitted codeword that corresponds to the portion of the noisy codeword.

Abstract: Disclosed are devices, systems and methods for providing hardware implementations of a quasi-cyclic syndrome decoder. An example method of reducing the complexity of a decoder includes receiving a noisy codeword that is a based on a transmitted codeword generated from a quasi-cyclic linear code; computing a plurality of syndromes based on the noisy codeword; selecting a first syndrome from the plurality of syndromes; generating a memory cell address as a function of the first syndrome; reading, based on the memory cell address, a coset leader corresponding to the first syndrome; and determining, based on the noisy codeword and the coset leader, a candidate version of the transmitted codeword.

Abstract: Techniques related to a QoS-aware decoder architecture for data storage are described. In an example, QoS specifications include a QOS latency specification indicative of an acceptable latency for completing the processing of a data read command. The decoder may store this QOS latency specification. In operation, the decoder generates a latency measurement indicative of the actual latency for the processing. If a comparison of the latency measurement and QOS latency specification indicates a violation of the QOS latency specification, the decoder can terminate the decoding and generate a decoding failure.

Abstract: Disclosed are devices, systems and methods for reducing the latency of a quasi-cyclic linear code decoder. An example method includes receiving a noisy codeword, the codeword having been generated from a quasi-cyclic linear code and provided to a communication channel prior to reception by the decoder; computing a syndrome based on the noisy codeword; generating a plurality of memory cell addresses, a first memory cell address being a function of the syndrome and subsequent memory cell addresses being within a predetermined address range of the function of the syndrome; reading, in a parallel manner to reduce the latency of the decoder, a plurality of error patterns from the plurality of memory cell addresses and computing a checksum for each of the plurality of error patterns; and determining, based on the checksum for each of the plurality of error patterns, a candidate version of the transmitted codeword.

Abstract: Disclosed are devices, systems and methods improving the convergence of a soft bit-flipping decoder in a non-volatile memory device. An example method includes receiving a noisy codeword, the codeword having been generated based on a parity check matrix of an LDPC code and provided to a communication channel prior to reception by the soft bit-flipping decoder, generating, based on the noisy codeword, one or more messages for passing between a plurality of variable nodes and a plurality of check nodes of the soft bit-flipping decoder, generating a reliability metric for each of the one or more messages, storing the reliability metric only for messages comprising magnitudes that are less than or equal to a predetermined threshold value; and performing, based on the one or more messages and the associated reliability metric for at least one of the one more messages, a single decoding iteration of the soft bit-flipping decoder.

Abstract: Disclosed are devices, systems and methods for improving a bit-flipping algorithm for an irregular LDPC code in a non-volatile memory device. An example method includes receiving a noisy codeword, the codeword having been generated from an irregular low-density parity-check code, performing a first iteration of a bit-flipping algorithm on the noisy codeword, computing a first syndrome based on an output codeword of the first iteration, determining that the first syndrome comprises a non-zero vector and no bits of the noisy codeword were flipped during the first iteration of the bit-flipping algorithm, flipping, based on the determining, at least one bit of the output codeword, the at least one bit corresponding to a variable node of the plurality of variable nodes with a smallest column weight connected to one or more unsatisfied check nodes of the plurality of check nodes, and computing, subsequent to the flipping, a second syndrome.

Abstract: Disclosed are devices, systems and methods improving the convergence of a soft bit-flipping decoder in a non-volatile memory device. An example method includes receiving a noisy codeword, the codeword having been generated based on a parity check matrix of an LDPC code and provided to a communication channel prior to reception by the soft bit-flipping decoder, generating, based on the noisy codeword, one or more messages for passing between a plurality of variable nodes and a plurality of check nodes of the soft bit-flipping decoder, generating a reliability metric for each of the one or more messages, storing the reliability metric only for messages comprising magnitudes that are less than or equal to a predetermined threshold value; and performing, based on the one or more messages and the associated reliability metric for at least one of the one more messages, a single decoding iteration of the soft bit-flipping decoder.

Abstract: An encoder for use in a memory system receives data bits and position information regarding a storage area among storage areas of a memory device in which the data bits are to be stored, determining the number of multiple random sequences to be used based on the position information, scrambling the data bits using the determined number of multiple random sequences, to generate scrambled sequences, selecting from among the generated scrambled sequences the scrambled sequence having the lowest number of a particular logic value, and outputting the selected scrambled sequence for storage in the storage area of the memory device.

Abstract: Memory controllers bit-flipping (BF) decoders and methods that selectively apply a checksum-aided error reduction (CA-ER) scheme to BF decoding of a low-density parity-check (LDPC) code. In decoding a codeword, a hard decision value resulting from decoding a select variable node is changed when a first condition is satisfied to yield an updated hard decision value. Also, when the first condition is satisfied, a current checksum value after processing the select variable node is updated using the updated hard decision value. The CA-ER scheme is applied when the updated checksum value is not reduced to a set minimum and a second condition based on a previous checksum value, calculated after a previous variable node is processed, is satisfied.

Abstract: Disclosed are devices, systems and methods for reducing the latency of a quasi-cyclic linear code decoder. An example method includes receiving a noisy codeword, the codeword having been generated from a quasi-cyclic linear code and provided to a communication channel prior to reception by the decoder; computing a syndrome based on the noisy codeword; generating a plurality of memory cell addresses, a first memory cell address being a function of the syndrome and subsequent memory cell addresses being within a predetermined address range of the function of the syndrome; reading, in a parallel manner to reduce the latency of the decoder, a plurality of error patterns from the plurality of memory cell addresses and computing a checksum for each of the plurality of error patterns; and determining, based on the checksum for each of the plurality of error patterns, a candidate version of the transmitted codeword.

Abstract: Disclosed are devices, systems and methods for providing hardware implementations of a quasi-cyclic syndrome decoder. An example method of reducing the complexity of a decoder includes receiving a noisy codeword that is a based on a transmitted codeword generated from a quasi-cyclic linear code; computing a plurality of syndromes based on the noisy codeword; selecting a first syndrome from the plurality of syndromes; generating a memory cell address as a function of the first syndrome; reading, based on the memory cell address, a coset leader corresponding to the first syndrome; and determining, based on the noisy codeword and the coset leader, a candidate version of the transmitted codeword.

Abstract: Disclosed are devices, systems and methods for improved decoding of a binary linear code. An example method includes receiving a noisy codeword; computing a syndrome based on the noisy codeword; identifying N error patterns that correspond to the syndrome; selecting M error patterns from the N error patterns, wherein M?N are positive integers, wherein a distance between a codeword corresponding to each of the M error patterns and the noisy codeword is less than a distance between a codeword corresponding to any other error pattern and the noisy codeword, and wherein the distance excludes a Hamming distance; modifying the noisy codeword based on each of the M error patterns one-at-a-time; and decoding the modified noisy codeword one-at-a-time until a successful decoding is achieved.

Abstract: Disclosed are devices, systems and methods for improving fast fail support for error correction in non-volatile memory. An exemplary method includes (a) receiving a codeword from a read operation in a fast fail mode, (b) initially configuring a maximum number of iterations (Nmax) and a set of values for a plurality of bit flipping thresholds for performing a decoding operation on the codeword, (c) performing a plurality of decoding iterations (N), each iteration using a subset of bit flipping thresholds, (d) calculating a remaining number of iterations (Nrem) as a difference between Nmax and N, (e) reconfiguring, based on Nrem and a latency requirement of the read operation in the fast fail mode, the set of values for the plurality of bit flipping thresholds to restart the decoding operation, and (f) repeating operations (c) through (e) until the codeword is successfully decoded or Nrem is less than or equal to 0.