An improvement of ODMRP for reliable delivery of busty traffic

An important issue in reliable multicasting in ad hoc networks is busty packet loss that arises when a link breaks due to node mobility. For a high data rate, a multicast receiver may miss a large number of packets until the route is reestablished, and recovering from such a loss may impose a huge overhead on the bandwidth-constrained ad hoc network. By the time a node detects loss, the requested data packets may no longer be available with other nodes, which only have a limited cache size. In on demand multicast routing protocol (ODMRP), the source periodically initiates a mechanism for multicast tree creation, through join queries. It is possible that a link goes down because of node mobility, and a member stops receiving data packets, until the next join query is received. In this work, we present an explicit join scheme for ODMRP, which allows a node to reconnect to the multicast tree through an alternative path, if the existing path goes down. The scheme has been simulated on global mobile simulator (GloMoSim), and has shown to be effective in removing the busty data losses due to link failures.