Relay-Based Multicast Routing in Multirate-Aware MANETs

This paper studies optimal relay-based multicast routing to improve throughput in multirate-aware MANETs. The main idea is trying to replace a lower rate transmission of upstream node with some higher rate transmissions by relay nodes to minimize the total transmission time of the upstream node and relay nodes. Firstly, we formulate this problem as an optimization problem and prove that it is NP-hard through set cover. Moreover, we propose a heuristic relay node selection algorithm (HRNSA) and analyze the transmission time gain of HRNSA over ODMRP. The simulation results show that our algorithm can increase throughput and decrease delay over ODMRP where upstream node broadcasts data packet to its downstream nodes with the minimum among the transmission rates between the node and downstream nodes.