Mobility-centric geocasting for mobile partitioned networks

We describe our design of a geocast service for mobile partitioned networks (MPNs). We focus mainly on minimizing the delivery latency. Our approach exploits the time-stability of the collective mobility pattern. In MPNs, in contrast to MANETs, the end-to-end path is frequently not available. Thus, communication in such networks becomes problematic. To overcome this difficulty, researchers propose a solution in which the nodepsilas mobility is exploited. This paradigm is often called mobility-assisted forwarding. In order to design routing protocols for MPNs, researchers study key mobility metrics, for example the inter-contact times between nodes. Based on the analysis of a real-life mobility trace, we show that the inter-contact time distribution is spatially dependent. This is a result of spatially heterogeneous mobility pattern that appears to be stable in time. We demonstrate that any georouting protocol designed to work in MPNs can benefit from knowing such an underlying mobility pattern. We propose an abstraction called mobility map that represents the collective mobility pattern. We also present how mobility maps can be used for georouting in MPNs and we also show a simple mechanism for the collaborative discovery of mobility maps. Finally, we propose a geocast protocol for MPNs - GeoMobCast - that explicitly uses mobility maps and is designed to minimize the expected message delay while maximizing the message delivery. We empirically evaluate the protocol by using simulations and we observe the improved performance, compared to other approaches.