ENCODING APPARATUS, DECODING APPARATUS, ENCODING METHOD, DECODING METHOD, AND COMMUNICATION SYSTEM

摘要

A position at which bit values are different is determined between a first code word obtained by encoding an information bit sequence, which is to be encoded, according to a pseudo cyclic encoding system and a second code word that is close to the first code word in terms of Hamming distance and that satisfies the parity check of the pseudo cyclic encoding system. A bit value, which is known on both of predetermined transmitting and receiving ends, is then inserted at the position of the information bit sequence to be encoded, and thereafter the encoding is performed, thereby generating a code word. When a signal based on the thus generated code word is received, it is determined whether or not the bit value at that position of a decoded code word, obtained by decoding the received signal, at which the known bit value has been inserted is different from a bit value established as a known value in advance. If yes, it is determined that the code word based on the received signal is not a correct code word even if that code word satisfies the parity check of the pseudo cyclic encoding system.