| 摘要 |
<p>A retransmission control method employs the LDPC code as an error correction code. Upon initial transmission, the method transmits a code word after coding by a predetermined coding ratio. Upon re-transmission, the method transmits an additional parity. A coding device (101) firstly creates a parity check matrix for initial transmission which has been optimized by a particular coding ratio and creates a parity check matrix for re-transmission which has been optimized stepwise by lowering the coding ratio. Next, the coding device (101) converts the parity check matrix for the initial transmission into a check matrix of the irreducible standard type (composed of check symbol generation matrix and unit matrix) and creates a generation matrix of the irreducible standard type for the initial transmission including the check symbol generation matrix. Next, the coding device (101) performs processing for creating a code word by using the generation matrix of the irreducible standard type for initial transmission and fixed-length information. On the other hand, when NAK is received from a communication device of the reception side, an additional parity is created in accordance with the parity check matrix corresponding to a coding ratio one step lower than the current coding ratio.</p> |
