HARQ for Predetermined-Rate Multicast Channel

This paper considers applying hybrid automatic repeat request (HARQ) to the predetermined-rate multicast data channel. The major differences in the HARQ design between multicast data and normal unicast data come from the fact that the multicast data assumes a predetermined data-rate using a given transmission frequency bandwidth and power, and multiple independent acknowledgement (ACK) and negative-acknowledgement (NAK) feedback from the mobile terminals. We present a new HARQ method based on superposition coding appropriate for the predetermined-rate multicast data. Computer simulation results reveal that the throughput performance is improved by using the proposed HARQ based on the superposition coding especially when there are many mobile terminals and the required data rate is relatively high.