Utility-based forwarding: a comparison in different mobility scenarios

Several proposals are available in the literature that deal with the problem of message forwarding in Opportunistic Networks (ONs). These proposals attempt to derive the path from source to destination that minimizes delivery latency and traveled hops, and maximizes the probability of successful delivery, while saving the overall system resources through a limitation of the number of message copies. Utilitybased forwarding achieves these goals through the use of functions that discriminate among nodes in terms of their utility to reach a destination. Although the approach is very promising, so far, there is no understanding about the tight relationship between utility functions and the mobility scenario in which they operate and, as a consequence, we are unable to design efficient solutions for practical ONs. In this work, we focus on this point by analysing five well known utility functions in five different scenarios. We establish relationships between the mechanisms adopted by the utility functions to discriminate among candidate relays, and the characteristics of the environment in terms of people mobility and the structure of their communities. The results can be useful to select an appropriate forwarding mechanism when deploying an experimental Opportunistic Network, and to design a novel utility function able to adapt to variable mobility patterns.