1. A decoding apparatus for carrying out a decoding process on a ring-R linear code, the decoding apparatus comprising: means for acquiring a coded word having a code length that is reduced by omission of one or more symbols from the coded word and for holding the coded word; means for attaching, to the coded word, a reliability level corresponding to each of the omitted symbols, the reliability level including known information comprising known symbols, wherein each of the known symbols have a known value; and means for repeatedly carrying out a decoding process using belief propagation on the coded word and the attached known information.
1. A decoding apparatus for carrying out a decoding process on a ring-R linear code, the decoding apparatus comprising: means for acquiring a coded word having a code length that is reduced by omission of one or more symbols from the coded word and for holding the coded word; means for attaching, to the coded word, a reliability level corresponding to each of the omitted symbols, the reliability level including known information comprising known symbols, wherein each of the known symbols have a known value; and means for repeatedly carrying out a decoding process using belief propagation on the coded word and the attached known information. 2. The decoding apparatus according to claim 1 wherein an LLR (Log Likelihood Ratio) is used as the level of reliability.