Effect of non-cooperative nodes in mobile DTNs

When applying delay-tolerant networking concepts to communication in mobile ad-hoc networks formed between mobile users, a general assumption is that users are willing to share own resources to support communication between others. However, we cannot assume that all users are altruistic in their behavior; instead, we have to deal with users who only make a limited or no contribution to the mobile community. Nodes not participating in communication only reduce the effective node density, but do not consume resources. Others act as sources and sinks but perform only limited or no forwarding and thus may impact the overall network performance. When considering routing in mobile DTNs, such selfish nodes have to be considered. We introduce two types of selfish nodes and evaluate their impact on message delivery performance for different routing protocols by means of simulation in different synthetic mobility models and with real-world traces. We find that their impact can be surprisingly low in our scenarios, suggesting that DTN communication can be quite robust against selfishness and that controlled non-cooperative behavior may be a suitable way to overcome resource limitations, such as battery depletion.