DECODING APPARATUS AND DECODING METHOD

摘要

A decoding apparatus including an operation unit to calculate a branch metric between first and second instants of time based on receiving likelihood data and an anterior likelihood, and to use, in a state transition in a butterfly represented by first and second states at the first instant of time and third and fourth states at the second instant of time, a first anterior cumulative metric for the first state, a second anterior cumulative metric for the second state and a first difference based on the branch metric between the first state and the third state and on a second difference between the first anterior cumulative metric and the second anterior cumulative metric to calculate a third anterior cumulative metric for the third state and a fourth anterior cumulative metric for each butterfly and at each instant of time, and a storage unit to store the second difference.

主权项

1. A decoding apparatus to calculate a posterior likelihood at each instant of time between a starting time and an end time, the decoding apparatus comprising:
an operation unit to calculate a branch metric for a branch between a first instant of time and a second instant of time subsequent to the first instant of time based on receiving likelihood data and an anterior likelihood, and to use, in a state transition in a butterfly represented by a first state and a second state at the first instant of time and a third state and a fourth state at the second instant of time, a first anterior cumulative metric for the first state, a second anterior cumulative metric for the second state and a first difference based on the branch metric between the first state at the first instant of time and the third state at the second instant of time and on a second difference between the first anterior cumulative metric for the first state and the second anterior cumulative metric for the second state to calculate a third anterior cumulative metric for the third state and a fourth anterior cumulative metric for each butterfly and at each instant of time; and a storage unit to store the second difference for each butterfly and at each instant of time.