Spray and Hop Distance Routing Protocol in Multiple-island DTN Scenarios

Especially in rural areas, a high-speed but high-cost data communication infrastructure is not always available. In such conditions, a store-carry-and-forward-based message relaying over existing vehicle networks is a promising approach to delivery of large data as delay and disruption tolerant networking (DTN). In this paper, reflecting a real example situation in Indonesia, we consider DTN message delivery scenarios over multiple islands where adjacent islands are connected only by ferry boat. The source and destination nodes of messages are stationary and located marginal islands. Messages are relayed by cars and buses in each island and by ferries between islands. We adapt our previously proposed routing protocol to the multiple-island scenarios with some modification and evaluate its effectiveness in two cases of delivery direction. In this newly proposed version, namely adaptive-spray and hop-distance protocol (A-SnHD), the binary-spray forwarding is repeatedly used when a message reaches each island, and the hop distance-based forwarding is strictly used to prevent unnecessary transmission to wrong islands. Simulation results show that A-SnHD outperforms Epidemic and PRoPHETV2 regarding the total size of delivered messages and the overhead ratio.