Likelihood generation device, receiving apparatus, likelihood generation method, and optical transmission system

Abstract

A likelihood generation device is included in a receiving apparatus that receives a code-modulated signal including n−k information bits and k parity bits in N-dimensional arrangement, where N is a natural number greater than or equal to four, and n and k are natural numbers with k<n. The likelihood generation device includes: a temporary likelihood determination unit to determine, by using a table that includes an L-dimensional address space and stores a likelihood in each of the L-dimensional address spaces, likelihoods of an information bit and a parity bit that are transmitted by the code-modulated signal received, where L is a natural number with L<N; and a likelihood correction unit to update, among the likelihoods determined by the likelihood derivation unit, the likelihood of the information bit on a basis of a rule for generation of the parity bit.