Modeling of a Bus-based Disruption Tolerant Network Trace
Xiaolan Zhang, Jim Kurose, Brian Neil Levine, Don Towsley, Honggang Zhang · 2007
We study traces taken from UMass DieselNet, a Disruption-Tolerant Network consisting of WiFi nodes attached to buses. As buses travel their routes, they encounter other buses and in some cases are able to establish pair-wise connections and transfer data between them. We analyze the bus-tobus contact traces to characterize the contact processes between buses and its impact on DTN routing performance. We nd that the all-bus-pairs aggregated inter-contact times show no discernible pattern. However, the inter-contact times aggregated at a route level exhibit periodic behavior. Based on analysis of the deterministic inter-meeting times for bus pairs running on route pairs, and consideration of the variability in bus movement and the random failures to establish connections, we construct generative routelevel models that capture the above behavior, allowing one to generate synthetic DTN mobility traces. Through trace-driven simulations of epidemic routing, we nd that the epidemic performance predicted by traces generated with this ner -grained route-level model are much closer to the actual performance that would be realized in the operational system than traces generated using the coarse-grained all-buspairs aggregated model. This suggests the importance in choosing the right level of model granularity when modeling mobility-related measures such as inter-contact times in DTNs.