Effect of locality of node mobility on epidemic broadcasting in DTNs

In DTNs (Delay/Disruption-Tolerant Networks) composed of mobile nodes, when the node movement has spatial locality, the nodes repeatedly miss opportunities to forward messages to other nodes, thus lowering communication performance. In this paper, we analyze the effect of locality of node mobility on message dissemination speed in epidemic broadcasting. We represent the locality of node mobility using the positional distribution of nodes in a stationary state, and we present a method for deriving the ratio of infected nodes from the positional distribution. Based on the results of a numerical experiment where the positional distribution of nodes obeys a two-dimensional normal distribution, we show that the message dissemination speed is heavily restricted by the locality of node mobility. Moreover, we clarify that a heavy-tailed positional distribution leads to a low locality of node mobility and entails mostly unrestricted message dissemination speed.