Apparatus and method for retrnasmission in multi-hop relay wireless communication system

An apparatus and a method for retransmission in a multi-hop relay wireless communication system are provided to increase the channel throughput as a repeater transmits only the PDUs(Protocol Data Units) that an MS(Mobile Station) fails to receive from a BS(Base Station), without transmitting all the PDUs received from the BS. A BS creates data using a hierarchical constellation so that each PDU can be robust for various errors, and transmits the data to a repeater and an MS(511,512). The repeater confirms whether each of the PDUs contained in the received data has an error, determines the MCS(Modulation and Coding Scheme) level of PDUs which have been successfully received without errors, and transmits the determined MCS level to the BS. Using the MSC level, the BS executes the retransmission of the data. Meanwhile, the MS confirms whether each of the PDUs contained in the data received from the BS has an error, determines the MCS level of PDUs which have been successfully received without errors, and transmits the determined MCS level to the repeater. The repeater confirms PDUs to be retransmitted, based on the MCS level information received from the MS. In case that the confirmed PDUs have been successfully received from the BS without errors, the repeater retransmits the PDUs to the MS(513).