Safety information gathering via information carriers through a DTN in a disaster-stricken area

In the event of a disaster affecting a large area, failures in facilities or power shortage may disrupt public communication services, including the mobile phone service, making it difficult to check safety of individuals in the disaster-stricken area. This paper assumes that disaster victims have mobile terminals, and that a delay/disruption tolerant network (DTN) can be built to interconnect these terminals, the terminals of rescuers (who also serve as safety information carriers), and the servers in shelters within the area so that information about the safety of individuals can be gathered. It proposes a protocol to be used to send safety information from the terminal of a victim to that of an information carrier, and a protocol to be used to send safety information from the terminal of an information carrier to a shelter server. We have implemented these protocols on a network simulator. Using a network model in which victims are scattered randomly over a 1.2 km² area, we have evaluated the probability at which safety information reaches a shelter server and examined the process of data gathering, for different numbers of victims, different numbers of information carriers, etc. We have found that, when the number of information carriers is about one-fifth of the number of victims, the safety information reaching probability is as high as 95%.