Patent ID: 7676732

Claim:
A method for retransmitting coded bits by a transmitter in response to a retransmission request from a receiver in a mobile communication system which selects coded bits to be transmitted by puncturing coded bits output from an encoder at a given mother coding rate according to a predetermined puncturing pattern, and transmits from the transmitter to the receiver a stream of symbols obtained by symbol-mapping the selected coded bits by a given modulation technique, the method comprising the steps of: selecting a modulation technique to be used at retransmission as a modulation technique having a lower modulation order than a modulation technique used at initial transmission; distributing the transmission coded bits punctured by a puncturing pattern, said puncturing pattern selected to correspond to an HARO type utilized by the transmitter, into a plurality of streams of sub-packets having a given size, verifying if a packet is a retransmission packet, and if the packet is a retransmission packet, setting an amount of data to be retransmitted to be less than the amount of data transmitted in an initial transmission; selecting as many sub-packets as the number of coded bits that are to be symbol-mapped by the selected modulation technique among the streams of sub-packets; and symbol-mapping coded bits constituting the selected sub-packets by the selected modulation technique and transmitting the symbol-mapped coded bits to the receiver, wherein the coding rate at initial transmission is equal to the coding rate at retransmission.