Method and decoder for soft input decoding of generalized concatenated codes

A decoding device operable to apply soft input decoding for a generalized concatenated code (GCC) constructed from L inner nested linear binary block codes and L outer codes, wherein L≥2 denotes the number of levels of the GCC and the inner code of a higher level is a sub-code of the inner code of the preceding lower levels, if any, the decoding device comprising:

• a decoding circuit configured to iteratively decode level by level original data received from a data channel, and performing in each level:
• a first decoding step for decoding input data of the current level l based on the inner block codes of the current level l and providing respective decoded output data, the input data of the lowest level comprising the original data and the input data of each subsequent level being based on the decoding result of the previous level;
• and
• a subsequent second decoding step for decoding the outer code of the current level l based on the output data of the first decoding step to estimate a decoding result of the current level l, wherein the decoding result of the highest level is output as decoded data;
• wherein the first decoding step of at least one of the levels includes:
• sequential stack decoding of the input data of the current level l based on a trellis of the inner block code of the current level and using as a soft input information characterizing the reliability of the data channel, wherein the sequential stack decoding is configured to deliver only codewords comprised in the output data of that first decoding step which are represented by the trellis;
• and
• selecting as the output data of the first decoding step of the current level l:
• a first output data estimate resulting from the sequential stack decoding of the input data of the current level l, if its metric value rated according to a predetermined metric reaches or exceeds a predetermined threshold or is superior according to the metric to the respective metric value of a second output data estimate resulting from a second run of the sequential stack decoding in which the first output data estimate is excluded, and
• the second output data estimate otherwise.

A nonvolatile memory, the system comprising:

• a memory array including a plurality of cells configured to store a plurality of data bits and a plurality of parity bits that are calculated from the plurality of data bits according to a coding scheme based on generalized concatenated code (GCC) wherein the GCC is constructed from inner nested linear binary block codes and outer codes;
• and
• a decoding device configured to iteratively decode level by level original data received from a data channel, and performing in each level:
• a first decoding step for decoding input data of the current level l based on the inner block codes of the current level l and providing respective decoded output data, the input data of the lowest level comprising the original data and the input data of each subsequent level being based on the decoding result of the previous level;
• and
• a subsequent second decoding step for decoding the outer code of the current level l based on the output data of the first decoding step to estimate a decoding result of the current level l, wherein the decoding result of the highest level is output as decoded data;
• wherein the first decoding step of at least one of the levels includes:
• sequential stack decoding of the input data of the current level l based on a trellis of the inner block code of the current level and using as a soft input information characterizing the reliability of the data channel, wherein the sequential stack decoding is configured to deliver only codewords comprised in the output data of that first decoding step which are represented by the trellis;
• and
• selecting as the output data of the first decoding step of the current level l:
• a first output data estimate resulting from the sequential stack decoding of the input data of the current level l, if its metric value rated according to a predetermined metric reaches or exceeds a predetermined threshold or is superior according to the metric to the respective metric value of a second output data estimate resulting from a second run of the sequential stack decoding in which the first output data estimate is excluded, and
• the second output data estimate otherwise.

A computer program comprising instructions that when executed on a decoding device are operable to apply soft input decoding for a generalized concatenated code (GCC) constructed from L inner nested linear binary block codes and L outer codes, wherein L≥2 denotes the number of levels of the GCC and the inner code of a higher level is a sub-code of the inner code of the preceding lower levels, if any, the instructions executable to:

• iteratively decode level by level original data received from a data channel, and perform in each level:
• a first decoding step for decoding input data of the current level l based on the inner block codes of the current level l and providing respective decoded output data, the input data of the lowest level comprising the original data and the input data of each subsequent level being based on the decoding result of the previous level;
• and
• a subsequent second decoding step for decoding the outer code of the current level l based on the output data of the first decoding step to estimate a decoding result of the current level l, wherein the decoding result of the highest level is output as decoded data;
• wherein the first decoding step of at least one of the levels includes:
• sequential stack decoding of the input data of the current level l based on a trellis of the inner block code of the current level and using as a soft input information characterizing the reliability of the data channel, wherein the sequential stack decoding is configured to deliver only codewords comprised in the output data of that first decoding step which are represented by the trellis;
• and
• selecting as the output data of the first decoding step of the current level l:
• a first output data estimate resulting from the sequential stack decoding of the input data of the current level l, if its metric value rated according to a predetermined metric reaches or exceeds a predetermined threshold or is superior according to the metric to the respective metric value of a second output data estimate resulting from a second run of the sequential stack decoding in which the first output data estimate is excluded, and
• the second output data estimate otherwise.