Adaptive HARQ scheme for reliable multicast communications

In wireless multicast communications, the mitigation of distributed errors in different users is crucial. The corrupted packets in the transmission of multicast streaming can be recovered by retransmitting another redundancy version of the same packets or by transmitting a new parity packet generated by packet-level erasure encoders. In this paper, a hybrid automatic repeat request (HARQ) scheme is proposed for efficient multicast communications. The proposed scheme estimates the contributions of each candidate packet to the marginal recovery on the erroneous packets and then transmits the packet which generates the most marginal recovery. The length of coded bits in the redundancy versions can also be adjusted to further save the radio resources. Simulations are conducted to verify the throughput efficiency of the proposed scheme, which outperforms the conventional schemes in all the range of packet error rates.