Detector with soft pruning
AssigneeLSI Corporation
InventorsWu Chang, Victor Krachkovsky, Shaohua Yang, Haitao Xia
Life of this patent
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Abstract
Various embodiments of the present invention provide apparatuses, systems and methods for data detection in a detector with soft pruning. For example, a data detector is disclosed that includes a branch metric calculator operable to calculate branch metrics for transitions between states in a trellis for the data detector, and a branch metric offset circuit operable to apply branch metric offsets to the branch metrics to yield soft pruned branch metrics. The branch metric offsets comprise a range of probability values from zero percent to one hundred percent.
Claims20
A data detector comprising:
- a branch metric calculator operable to calculate branch metrics for transitions between states in a trellis for the data detector;
- and
- a branch metric offset circuit operable to apply branch metric offsets to the branch metrics to yield soft pruned branch metrics, wherein the branch metric offsets comprise a range of probability values from zero percent to one hundred percent, wherein a first group of the states originate at least one transition prohibited by the branch metric offsets and wherein a second group of the states do not originate transitions prohibited by the branch metric offsets, and wherein the branch metric offset circuit is operable to apply the branch metric offsets to the branch metrics for the transitions from the first group of states and to the branch metrics for the transitions from the second group of states.
A method of detecting data in a data detector with soft pruning, comprising:
- calculating a branch metric for each of a plurality of transitions between states in the data detector;
- deriving branch metric offsets from probabilities of data patterns at an input to the data detector, wherein the branch metric offsets are derived by counting occurrences of each possible pattern in a sliding window applied to a data stream at an output of an encoder upstream of the data detector to yield probabilities of occurrence;
- applying at least one of the branch metrics offset to each of the branch metrics to yield soft pruned branch metrics;
- and
- calculating hard decisions based on the soft pruned branch metrics.
A storage system comprising:
- a storage medium maintaining a data set;
- a read/write head assembly operable to write the data set to the storage medium and to read the data set from the storage medium;
- a maximum transition run encoder operable to encode the data set to yield encoded data before it is written to the storage medium and to limit a number of successive transitions in the encoded data;
- and
- a data detector operable to detect values of the encoded data using branch metrics for transitions between states in a trellis and to apply branch metric offsets to all the transitions, wherein the branch metric offsets are based on probabilities of occurrence in data patterns in the encoded data, and wherein the data detector is operable to stop applying the branch metric offsets when data at an input of the data detector violates the limit on the number of successive transitions.
Dependencies are inferred from the claim text.