Coding device, decoding device, coding method, decoding method, and communication system

Abstract

Positions holding different bit values between a first code word, which is obtained by coding an information bit sequence based on a coding method utilizing quasi-cyclic codes, and a second code word, which has the close Hamming distance from the first code word and satisfies a parity check of the coding method, are identified. Thereafter, a code word is generated by inserting bit values known to the transmitter and receiver into the identified positions of the information bit sequence and coding the information bit sequence. Upon reception of a signal based on the generated code word, the receiver judges whether known bit values held by corresponding positions in a code word obtained by decoding the received signal are the same as preset bit values. If the judgment result is negative, the code word based on the received signal is judges as erroneous even when it satisfies the parity check.