A Multicast Retransmission Scheme Using Negative ACK in Wireless Networks

This paper presents a multicast retransmission scheme (MRS) in wireless networks. MRS adds negative ACK and packet retransmission into UDP. There are two novelties presented in this paper. First, retransmission for lost packets is sufficiently delayed such that the lost packets in different members of the same multicasting group can be retransmitted at the same time. Second, the RTO (retransmission time out) values for retransmitting the lost packets are dynamically adjusted by considering the causes of loss, i.e., whether the loss is caused by wireless interferences or by network congestion. For the purpose of demonstration, we implement the MRS on a Linux platform. Our experiments show that the number of retransmitted packets can be significantly reduced, and the quality of images can be improved substantially.