Energy-efficient contact probing in opportunistic mobile networks

In Opportunistic Mobile Networks (OppNets), data is opportunistically exchanged between nodes who encounter each other. In order to enable such data exchanges, nodes in the network have to probe their environment continually, so as to discover neighbor nodes. This can be an extremely energy-consuming process. If nodes probe very frequently, they will consume a lot of energy, and might be energy inefficient. On the other hand, infrequent contact probing might cause nodes to miss many of their contacts, and thus opportunities to exchange data are lost. Therefore, there exists a trade-off between energy efficiency and the contact opportunities in OppNets. In this paper, in order to investigate this trade-off, we first propose a model to quantify the detecting probability in OppNets, using the Random WayPoint (RWP) model. Then, extensive simulations are conducted to validate the correctness of our proposed model. Finally, based on the proposed model, we analyze the trade-off between energy efficiency and the total number of effective contacts under different situations. Our results show that the good trade-off points are obviously different when the speed of nodes is different. Moreover, the detecting probability increases as the speed of nodes decreases, while the total number of effective contacts increases as the speed of nodes increases.