Research on Custody Transfer Service in Delay Tolerant Network

A delay/disruption tolerant network (DTN) architecture was proposed to effectively support communication in challenging scenarios characterized by intermittent connectivity and long latency. The custody transfer (CT) mechanism is used to improve the reliability of DTN. We proposed a mathematical model of the DTN data link. Based on this model, we simplified a link containing both nodes with and without CT into a link containing only nodes with CT. We developed a NS2-based DTN simulator and conducted three simulations. The first two simulations are conducted on links whose hops are from 2 to 10, where all relay nodes accept or deny CT. The simulation results show that the destination node receives far more data when CT is available; furthermore, the storage consumption of the source node decreases. The third simulation is conducted to evaluate the effect of retransmission timer on storage consumption and retransmission times. The simulation results show that the value of retransmission timer that is greater than the maximum round-trip-time between adjacent nodes and less than the minimum disconnection interval is a good candidate for DTN data transfer.