In this paper, we present MobiTrade, a utility driven trading system for efficient content dissemination on top of a disruption tolerant network. While simple tit-for-tat (TFT) mechanisms can force nodes to "give one to get one", dealing with the inherent tendency of peers to take much but give back little, they can quickly lead to deadlocks when some (or most) of interesting content must be somehow fetched across the network. To resolve this, MobiTrade proposes a trading mechanism that allows a node ("merchant") to buy, store, and carry content for other nodes (its "clients") so that it can later trade it for content it is personally interested in. To exploit this extra degree of freedom, MobiTrade nodes continuously profile the type of content requested and the collaboration level of encountered devices. An appropriate utility function is then used to collect an optimal inventory that maximizes the expected value of stored content for future encounters, matched to the observed mobility patterns, interest patterns, and collaboration levels of encountered nodes. Using NS3 simulations based on synthetic and real mobility traces, we show that MobiTrade achieves up to 2× higher query success rates compared to other content dissemination schemes. Furthermore, we show that MobiTrade successfully isolates selfish devices.
