Development of DTN Buffer Management for Rapid Grasping of Disaster Situations While Minimizing AoI

At a disaster situation, it is important to gather information both of victims and disaster stricken area. In addition, the importance of fast data gathering, grows rapidly if such information frequently changes with time. Many systems have been proposed to gather disaster information at disaster affected area based on DTN (Delay/Disruption Tolerant Networking) working effectively regardless the damages of telecommunications infrastructure. However, most of them being developed to use evaluation indicators such as message arrival rate and message delay. Those indicators, however, do not well represent the characteristics of the performance for gathering frequently changing information. Therefore, this paper proposes to use AoI (Age of Information) as an indicator. According to the performance evaluations that, firstly we clarify that transmission order management according to the message priority reduces AoI of most important messages, approx. 50% compared with AoI of conventional method when the number of senders lager than 20. In addition, we also clarify that buffer allocation on the basis of the priority level further reduces unneeded AoI of low priority messages, approx. 60% compared with AoI without buffer management when the number of senders lager than 20.