Encoding circuit, decoding circuit, and decoding method

A decoding circuit comprising:

• likelihood calculating circuitry capable of calculating likelihood information of a polar code of a first code length, the likelihood calculating circuitry being configured to calculate likelihood information corresponding to a polar code of a second code length less than or equal to the first code length on the basis of an input signal and a decoding interim result;
• decoding processing circuitry to select decoding candidates on a bit-by-bit basis by sequential decoding using the likelihood information calculated by the likelihood calculating circuitry;
• first bit arrangement changing circuitry to generate a first bit sequence of the first code length by arranging the decoding candidates selected by the decoding processing circuitry in the first bit sequence according to an arrangement rule that depends on a ratio of the second code length and the first code length;
• first polar encoding circuitry to perform polar encoding on the first bit sequence, and input the first bit sequence polar-encoded to the likelihood calculating circuitry as the decoding interim result;
• control circuitry to control the likelihood calculating circuitry and the decoding processing circuitry on the basis of the second code length such that sequential decoding is performed according to the second code length;
• decoded bit selecting circuitry to, in response to the decoding candidates of a data length to be processed being calculated by the decoding processing circuitry, select decoded bits as a decoding result using the decoding candidates;
• and
• frozen bit removing circuitry to remove a frozen bit from the decoding result.

A decoding method comprising:

• a likelihood computing in which likelihood information of a polar code of a first code length is calculable, and likelihood information corresponding to a polar code of a second code length less than or equal to the first code length is calculated on the basis of an input signal and a decoding interim result;
• a decoding candidate selecting of selecting decoding candidates sequentially on a bit-by-bit basis using the likelihood information calculated in the likelihood computing;
• a first bit arrangement changing of generating a first bit sequence of the first code length by arranging the decoding candidates selected in the decoding candidate selecting in the first bit sequence according to an arrangement rule that depends on a ratio of the second code length and the first code length;
• a first polar encoding of performing polar encoding on the first bit sequence, and inputting the first bit sequence polar-encoded to the likelihood computing as the decoding interim result;
• a control of controlling the likelihood computing and the decoding candidate selecting on the basis of the second code length such that sequential decoding is performed according to the second code length;
• a decoded bit selecting of, in response to the decoding candidates of a data length to be computed being calculated in the decoding candidate selecting, selecting decoded bits as a decoding result using the decoding candidates;
• and
• a frozen bit removing of removing a frozen bit from the decoding result.