Decoding method and apparatus
AssigneeSony Corporation
InventorToshiyuki Miyauchi
Life of this patent
Estimating the term…
Abstract
A path memory and likelihood update circuit 16 provided in a two-step SOVA decoder includes eight RAMs 32a, 32b, . . . , 32h to store path selection information indicative of a selection of a most likely path in each state of an input convolutional code, a trace result memory circuit 34 to store the result of most likely path tracing and output it as delay trace result signal s42, a most likely path Δ memory circuit 35 to select and store a metric difference for the most likely path based on the delay trace result signal s42 and output it as delay most likely Δ signal s43, and a minimum Δ memory circuits 37a and 37b to store a minimum value of the metric difference for the most likely path in each state of the convolutional code based on the delay trace result signal s42 and delay most likely Δ signal s43.
Claims17
A decoding method of decoding, in the soft-output Viterbi manner, an input convolutional code to provide a decoded data and likelihood information, comprising steps of
- storing, into a random-accessible path selection information storing means, path selection information indicative of more likely paths selected at each transition of the convolutional code;
- storing, based on a trace result signal indicative of a result of a tracing effected for a terminating length based on the path selection information, a result of tracing of a most likely path being a sequence most likely to that of the convolutional code into a trace result storing means;
- selecting, based on a delayed trace result signal indicative of a result of tracing of the most likely path stored in the trace result storing means and thus delayed, a metric difference for the most likely path from a metric difference delay signal resulted from a delay of the metric difference when the more likely paths are selected at each transition of the convolutional code, and storing it into a metric difference storing means;
- storing, based on the delayed trace result signal and a delayed most likely metric difference signal indicative of a metric difference for the most likely path stored in the metric difference storing means, a minimum value of the metric difference for the most likely path into a minimum value storing means at each transition of the convolutional code;
- and
- acquiring the likelihood information based on the minimum value.
A decoder for decoding, in the soft-output Viterbi manner, an input convolutional code to provide a decoded data and likelihood information, the apparatus comprising:
- means for storing, into a random-accessible path selection information storing means, path selection information indicative of more likely paths selected at each transition of the convolutional code;
- means for storing, based on a trace result signal indicative of a result of a tracing effected for a terminating length based on the path selection information, a result of tracing of a most likely path being a sequence most likely to that of the convolutional code into a trace result storing means;
- means for selecting, based on a delayed trace result signal indicative of a result of tracing of the most likely path stored in the trace result storing means and thus delayed, a metric difference for the most likely path from a metric difference delay signal resulted from a delay of the metric difference when the more likely paths are selected at each transition of the convolutional code, and storing it into a metric difference storing means;
- and means for storing, based on the delayed trace result signal and a delayed most likely metric difference signal indicative of a metric difference for the most likely path stored in the metric difference storing means, a minimum value of the metric difference for the most likely path into a minimum value storing means at each transition of the convolutional code;
- and the likelihood information being acquired based on the minimum value.
Dependencies are inferred from the claim text.