System and method for decoding iterations and dynamic scaling
A decoder is configured to perform, for a unit of data received by the decoder, a plurality of decoding iterations in which a plurality of messages are passed between a plurality of check nodes and a plurality of variable nodes, each message indicating a degree of reliability in an observed outcome of data. The decoder determines, for each of the plurality of decoding iterations, whether a trigger condition is satisfied based on an internal state of the decoder and, when a trigger condition is determined to be satisfied during a respective decoding iteration, scales one or more respective messages of the plurality of messages during a subsequent decoding iteration. The unit of data is decoded based on the plurality of decoding iterations and at least one scaled message resulting from the trigger condition being satisfied during the respective decoding iteration.
1. An apparatus, comprising:
a decoder configured to:
perform a plurality of decoding iterations based on a plurality of messages;
determine whether one or more trigger conditions for scaling have occurred, based at least on one or more internal states of the decoder;
in response to determining that one or more trigger conditions for scaling have occurred, scale one or more messages resulting from one or more of the plurality of decoding iterations; and
perform one or more next decoding iterations based on the scaled one or more messages.
2. The apparatus of claim 1 , wherein the one or more messages comprise one or more of: a scalar representing an estimated reliability of a single unit of data; and a vector representing an estimated reliability of a single unit of data.
3. The apparatus of claim 1 , wherein the one or more messages comprise one or more log-likelihood ratios (LLRs).
4. The apparatus of claim 3 , wherein the decoder is configured to scale at least one of the one or more messages based on reducing a numerical range spanned by an LLR.
5. The apparatus of claim 3 , wherein the decoder configured to scale the one or more messages comprises a shifter to right shift an LLR and then truncate or round the right shifted LLR.
6. The apparatus of claim 3 , wherein the decoder configured to determine whether one or more trigger conditions for scaling have occurred comprises the decoder configured to determine that absolute values of a predetermined number of the LLRs are greater than a predetermined limit.
7. The apparatus of claim 1 , wherein the decoder configured to determine whether one or more trigger conditions for scaling have occurred comprises the decoder configured to determine that a predetermined number of the plurality of decoding iterations has been performed.
8. The apparatus of claim 7 , wherein the predetermined number of the plurality of decoding iterations is a predetermined number of the plurality of decoding iterations since a prior scaling operation.
9. The apparatus of claim 1 , wherein the decoder comprises a check node unit configured to determine whether one or more parity check conditions have been satisfied in order to determine whether to terminate the plurality of decoding iterations.
10. The apparatus of claim 1 , wherein the decoder configured to determine whether one or more trigger conditions for scaling have occurred comprises the decoder configured to determine that a current number of unsatisfied checks on at least a portion of the plurality of messages exchanged between a plurality of variable nodes and a plurality of check nodes does not satisfy a predetermined threshold and that a predetermined number of decoding iterations has been performed since a prior scaling operation.
11. The apparatus of claim 1 , wherein:
the decoder comprises a first memory and a second memory, and
the decoder is configured to work with a parity check matrix including a plurality of layers and configured to:
trigger scaling of an output from the first memory at a sub-iteration associated with processing a first layer of the plurality of layers; and
trigger scaling of an output from the second memory at sub-iterations associated with processing of the first layer and one or more of the plurality of layers other than the first layer.
12. A machine-implemented method, comprising:
performing, in a decoder, a plurality of decoding iterations based on a plurality of messages;
determining whether one or more trigger conditions for scaling have occurred, based at least on one or more internal states of the decoder;
scaling one or more messages produced from one or more of the plurality of decoding iterations when the one or more trigger conditions have occurred; and
performing one or more next decoding iterations based on the scaled one or more messages.
13. The machine-implemented method of claim 12 , wherein the one or more messages comprise one or more of: a scalar representing an estimated reliability of a single unit of data; and a vector representing an estimated reliability of a single unit of data.
14. The machine-implemented method of claim 12 , wherein the one or more messages comprise one or more log-likelihood ratios (LLRs).
15. The machine-implemented method of claim 14 , wherein the scaling comprising scaling at least one of the one or more messages based on reducing a numerical range spanned by an LLR.
16. The machine-implemented method of claim 14 , wherein the determining comprises determining that absolute values of a predetermined number of the LLRs are greater than a predetermined limit.
17. The machine-implemented method of claim 12 , wherein the determining comprises determining that a predetermined number of the plurality of decoding iterations has been performed, and wherein the predetermined number of the plurality of decoding iterations is a predetermined number of the plurality of decoding iterations since a prior scaling operation.
18. A system, comprising:
means for performing, in a decoder, a plurality of decoding iterations based on a plurality of messages;
means for determining whether one or more trigger conditions for scaling have occurred, based at least on one or more internal states of the decoder;
means for scaling one or more messages produced from one or more of the plurality of decoding iterations when the one or more trigger conditions have occurred; and
means for performing one or more next decoding iterations based on the scaled one or more messages.
19. The system of claim 18 , wherein the one or more messages comprise one or more of: a scalar representing an estimated reliability of a single unit of data; and a vector representing an estimated reliability of a single unit of data.
20. The system of claim 18 , wherein the one or more messages comprise one or more log-likelihood ratios (LLRs).