A content freshness enhancement with infrastructures in mobile opportunistic networks

In mobile opportunistic networks, we investigate the effect of infrastructures on content update process. In the network, an information provider continuously generates a time-sensitive content (e.g., news, twits or military commands) whose freshness decreases with time. This information is propagated to users throughout opportunistic contacts. Users prefer to have the more recently generated (i.e., up-to-date) content. In that, they utilize a content age to compare their freshness and share only the smaller age content when an opportunistic contact occurs. Based on this update process, here we analyze the freshness enhancement of users by adding an infrastructure to the contact-based network. This scenario is available when new communication technologies such as satellite or AWACS are used in the network. We propose several content update rules which reflect network environments and users access the infrastructure to update content by following the rules. It is reasonably expected that users receive a freshness improvement under the use of infrastructures. However, to quantify the enhancement degree is not well-defined until now and remains challenging. By using an ODE model, we show the degree of freshness improvement which users receive. We explain the reasoning of how our model can capture the user freshness and derive an analytical solution for each suggested rule. To validate our approach, we test our update rules on real traces and compare the results between our analytical solutions and ones from traces.