A method of receiving data packets in a mobile communication system from two relay stations, RS1 and RS2, the method comprising: receiving a first data packet including at least one subpacket from a base station; receiving a second data packet including at least one subpacket from the RS1, wherein the second data packet is a relayed data packet of the first data packet; and receiving a third data packet including at least one subpacket from the RS2, wherein the third data packet is a relayed data packet of the first data packet, wherein a first subpacket of the first data packet, a first subpacket of the second data packet, and a first subpacket of the third data packet are received via a main channel, respectively, and wherein at least one subsequent subpacket of the first data packet, at least one subsequent subpacket of the second data packet, and at least one subsequent subpacket of the third data packet are received via at least one assistant channel, respectively, characterized by the first subpacket of the second data packet received from the RS1 being a space-time coded version of the first subpacket of the first data packet received from the base station, the first subpacket of the third data packet received from the RS2 being a space-time coded version of the first subpacket of the first data packet received from the base station, and the first subpacket of the second data packet received from the RS1 having different parity bits than those of the first subpacket of the first data packet received from the base station, and the first subpacket of the third data packet received from the RS2 having different parity bits than those of the first subpacket of the first data packet received from the base station. receiving a first data packet including at least one subpacket from a base station; receiving a second data packet including at least one subpacket from the RS1, wherein the second data packet is a relayed data packet of the first data packet; and receiving a third data packet including at least one subpacket from the RS2, wherein the third data packet is a relayed data packet of the first data packet, wherein a first subpacket of the first data packet, a first subpacket of the second data packet, and a first subpacket of the third data packet are received via a main channel, respectively, and wherein at least one subsequent subpacket of the first data packet, at least one subsequent subpacket of the second data packet, and at least one subsequent subpacket of the third data packet are received via at least one assistant channel, respectively, the first subpacket of the second data packet received from the RS1 being a space-time coded version of the first subpacket of the first data packet received from the base station, the first subpacket of the third data packet received from the RS2 being a space-time coded version of the first subpacket of the first data packet received from the base station, and the first subpacket of the second data packet received from the RS1 having different parity bits than those of the first subpacket of the first data packet received from the base station, and the first subpacket of the third data packet received from the RS2 having different parity bits than those of the first subpacket of the first data packet received from the base station.