Viterbi decoder
AssigneeSony Corporation
InventorIzumi Hatakeyama
Life of this patent
Estimating the term…
Abstract
A Viterbi decoder for decoding a convolution coded reception signal. The Viterbi decoding uses an algorithm for efficiently executing the maximum likelihood decoding using a convolution code by selecting a path locating at the minimum distance from a reception series between two paths which are joined. Since it is necessary to store a state metric of each state, after the state metric of the surviving path was calculated by ACS calculation, it is considered to normalize metrics. However, this results in a large circuit scale and a low processing speed. Therefore, in this invention, a maximum likelihood value of a present state metric is detected from a maximum likelihood branch metric pair before the ACS calculation and the preceding maximum likelihood state metric pair and metrics are normalized by using the maximum likelihood value.
Claims7
A Viterbi decoder for decoding a convolution code comprising:
- branch metric calculating means for calculating a branch metric of an input signal;
- ACS calculating means for selecting a surviving path and calculating a state metric;
- branch metric pair detecting means connected to an output of the branch metric calculating means for receiving branch metrics from the branch metric calculating means and detecting a maximum likelihood branch metric pair before ACS calculation from said branch metrics from the branch metric calculating means;
- state metric pair detecting means for receiving state metrics from the ACS calculating means and detecting a preceding maximum likelihood state metric pair from said state metrics;
- maximum likelihood value detecting means connected to an output of the branch metric pair detecting means, for receiving the preceding maximum likelihood state metric pair, and detecting a maximum likelihood value of a present state metric from the maximum likelihood branch metric pair before the ACS calculation and the preceding maximum likelihood state metric pair, and
- a metric normalization means, connected to an output of the maximum likelihood value detecting means, for normalizing metrics by using a maximum likelihood value obtained by said maximum likelihood value detecting means.
A Viterbi decoder for decoding a convolution code comprising:
- branch metric calculating means for calculating a branch metric of an input signal;
- ACS calculating means for selecting a surviving path and calculating a state metric;
- branch metric pair detecting means connected to an output of the branch metric calculating means for receiving branch metrics from the branch metric calculating means and detecting a maximum likelihood branch metric pair before ACS calculation from said branch metrics from the branch metric calculating means;
- state metric pair detecting means for receiving state metrics after ACS calculation and detecting a preceding maximum likelihood state metric pair from said state metrics;
- maximum likelihood value detecting means connected to an output of the branch metric pair detecting means and to an output of the state metric pair detecting means, for receiving the preceding maximum likelihood state metric pair, and detecting a maximum likelihood value of a present state metric from the maximum likelihood branch metric pair and the preceding maximum likelihood state metric pair;
- and
- a metric normalization means, connected to an output of the maximum likelihood value detecting means, for normalizing metrics after the ACS calculation by using the maximum likelihood value detected by said maximum likelihood value detecting means.
Dependencies are inferred from the claim text.