Scheduling of iterative decoding depending on soft inputs

A method for decoding, comprising:

• in a decoder comprising multiple Variable-Node Circuits (VNCs) that individually hold one or more variables of an Error Correction Code (ECC) that is representable by a plurality of check equations defined over the variables, wherein a given VNC among the VNCs is associated with a plurality of the variables,
• receiving for decoding a code word that was encoded using the ECC, the code word comprising multiple variables having m-bit values, m being a positive integer;
• further receiving multiple reliability levels assigned respectively to the variables of the received code word, wherein values of the reliability levels comprise predefined binary reliability values having a High Reliability (HR) value and a Low Reliability (LR) value;
• decoding the received code word by applying to the code word a sequence of iterations, including, in a given iteration in the sequence, holding for the given iteration predefined first and second skipping thresholds associated respectively with the LR and the HR values, evaluating a number of the variables associated with the given VNC that are assigned to the LR value, and deciding whether to skip or process the given VNC based on the first skipping threshold when the evaluated number is higher than a predefined threshold number, or based on the second skipping threshold when the evaluated number is lower than or equal to the predefined threshold number;
• and
• when the given VNC is selected for processing, making a decision whether or not to update one or more of the values of the variables associated with the given VNC, and applying the decision by the given VNC.

A decoder, comprising:

• multiple Variable-Node Circuits (VNCs), configured to individually hold one or more variables having binary values of an Error Correction Code (ECC) that is representable by a plurality of check equations defined over the variables, wherein a given VNC among the VNCs is associated with a plurality of the variables;
• and
• logic circuitry, configured to:
• receive for decoding a code word that was encoded using the ECC, the code word comprising multiple variables having m-bit values, m being a positive integer;
• further receive multiple reliability levels assigned respectively to the variables of the received code word, wherein values of the reliability levels belong to a set of two or more predefined reliability values;
• decode the received code word by applying to the code word a sequence of iterations, including, in a given iteration in the sequence, deciding whether to skip or process the given VNC based on how many of the variables associated with the given VNC have been assigned to a given reliability value;
• and
• when the given VNC is selected for processing, make a decision whether or not to update one or more of the values of the variables associated with the given VNC, and apply the decision by the given VNC,
• wherein, in making the decision, the logic circuitry is configured to calculate a score value for a given variable of the given VNC, based on (i) a number of the check equations of the ECC in which the given variable participates and that are unsatisfied, (ii) an indication of whether the binary value of the given variable differs from a corresponding binary value in the received code word, and (iii) a predefined weight value applied to the indication, the weight value depending on the reliability level assigned to the given variable, the score value being indicative of a confidence level of the given variable holding a correct binary value corresponding to a successfully decoded version of the code word, and to make the decision for the given variable based on the score value.

A method for decoding, comprising:

• in a decoder comprising multiple Variable-Node Circuits (VNCs) that individually hold one or more variables having binary values of an Error Correction Code (ECC) that is representable by a plurality of check equations defined over the variables, wherein a given VNC among the VNCs is associated with a plurality of the variables,
• receiving for decoding a code word that was encoded using the ECC, the code word comprising multiple variables having m-bit values, m being a positive integer;
• further receiving multiple reliability levels assigned respectively to the variables of the received code word, wherein values of the reliability levels belong to a set of two or more predefined reliability values;
• decoding the received code word by applying to the code word a sequence of iterations, including, in a given iteration in the sequence, deciding whether to skip or process the given VNC based on how many of the variables associated with the given VNC have been assigned to a given reliability value;
• and
• when the given VNC is selected for processing, making a decision whether or not to update one or more of the values of the variables associated with the given VNC, and applying the decision by the given VNC,
• wherein making the decision comprises calculating a score value for a given variable of the given VNC, based on (i) a number of the check equations of the ECC in which the given variable participates and that are unsatisfied, (ii) an indication of whether the binary value of the given variable differs from a corresponding binary value in the received code word, and (iii) a predefined weight value applied to the indication, the weight value depending on the reliability level assigned to the given variable, the score value being indicative of a confidence level of the given variable holding a correct binary value corresponding to a successfully decoded version of the code word, and making the decision for the given variable based on the score value.