Billiards: Policy-based Session Control Protocol in Disruption Tolerant Sensor Networks

Recently there has been a great deal of research on using mobility in sensor networks to assist their sensing tasks. In this paper, we propose a policy-based session control protocol for disruption tolerant sensor networks (DTSNs) called Billiards. In a DTSN, all messages are transported by the physical motion of participants (mobile nodes) in the network. When a large volume of data or continuous data is required to be transferred, there exists a problem determining how the data is fragmented and how the mobile nodes are formed for carrying the data to the destination. To overcome these issues, we propose a suitable method of session control which is determined based on a state of surrounding mobile nodes such as number, maximum-velocity and buffer-size. Billiards also takes a system policy of either delay minimization or energy efficiency into consideration. In this paper, we describe the protocol and model of Billiards and analyze the each model. We also show its effectiveness through experiments with utilizing mobile robots.