Route design for multiple ferries in delay tolerant networks

Routing mechanisms in delay tolerant networks (DTNs) usually rely on nodes' mobilities to bridge gaps in space and time. Though they may depend on the movements of ordinary nodes, it is more desirable to introduce special mobile nodes called ferries dedicated to communication in DTNs. In this paper, we concentrate on the route design problem for multiple ferries. We introduce an analytically tractable model to describe message delivery delay in three different schemes for multiple ferry routing. We give analytical results that reveal the tradeoff between the cost of using more ferries and the performance gains. Driven by the analysis, we propose routing algorithms that can match our theoretical results well. The algorithms are evaluated under extensive network settings via simulations. The results show that our algorithms can reduce the message delivery delay over existing routing algorithms, especially when the nodes are not uniformly distributed in space.