In a mobile communication system including a transmitter and a receiver, an LDPC code is generated by encoding received information data such that a fifth partial matrix obtained by combining a second partial matrix having even-numbered columns of a first partial matrix corresponding to the information data with a fourth partial matrix having odd-numbered columns of a third partial matrix corresponding to a parity, and an eighth partial matrix obtained by combining a sixth partial matrix having odd-numbered columns of the first partial matrix with a seventh partial matrix having even-numbered columns of the third partial matrix correspond to a ninth partial matrix obtained by exclusive-ORing the first partial matrix and the third partial matrix and a parity check matrix having a predetermined rank in a binary field. A space-time LDPC code is generated by spatial-mapping the LDPC code according to a predetermined spatial mapping scheme.