1. A method to transmit a signal in a signal transmission apparatus, the method comprising: generating a final codeword vector by encoding an information vector including A (A≧1) information bits using one of a child parity check matrix and a parent parity check matrix; and transmitting the final codeword vector, wherein the parent parity check matrix and the child parity check matrix each comprise a plurality of blocks, each of the plurality of blocks having a block matrix P a pq mapped thereto; each block matrix including a zero (0) matrix when an exponent value a pq of the block matrix P a pq is −1, and each block matrix including an identity matrix when the exponent value a pq is 1, and wherein the parent parity check matrix comprises a first information part mapped to the information vector, a first parity part mapped to the B parity bits, and a second parity part mapped to the C parity bits.