Performance evaluation of custody transfer in Mars-to-Earth DTN communications

A delay tolerant network (DTN) architecture is proposed to deal with the challenges faced in space communication, such as the long propagation delays, intermittent connectivity, and asymmetric data rates. The DTN architecture utilizes a store-and-forward mechanism called as custody transfer (CT) to enhance the reliability of communications. In this study, we consider a Mars-to-Earth communication scenario in which the Mars orbiter is used as a relay to retransmit data from a rover located near Valles Marineris on Mars. The access time between nodes is calculated using Satellite Tool Kit to approximate a real scenario. The use of CT in this scenario is evaluated through a simulation. Its performance was analyzed to compare the delivery ratio, average transmission delay, number of retransmissions, and storage consumption under different storage capacities, retransmission timeouts, and bundle lifetimes. The results serve to provide an understanding of how CT-related parameters can be configured to achieve optimal communication performance.