Throughput delay tradeoff for wireless multicast using hybrid-ARQ protocols

In this paper, we present a hybrid ARQ scheme for wireless multicast, i.e., common information broadcast. In this scheme, incremental redundancy channel coding and packet retransmission are employed. This scheme enables the reliable delivery of the same copy of information to different users with mild delay. In addition, the design of the feedback channel for this scheme can be greatly simplified as no effort must be expended to combat the cross user interference. In this paper, we study the delay and throughput trade-offs for three specific schemes including generalized slotted ALOHA (GSA), repetition time diversity (RTD), and general incremental redundancy (INR). We also prove that when we increase the rate per packet linearly with K, we can obtain a linear scaling for both the throughput and the delay with respect to K. This is the best optimal scaling law for wireless mulitcast.