Size-Optimal Network-Coded Bundle Aggregation for Earth-Lunar Disruption-Tolerant Network via Markov Decision

In recent years, a disruption-tolerant network (DTN) has attracted significant attention regarding lunar exploration, as they can be employed in various relay spacecraft, such as lunar orbiters, due to their excellent constant all-time coverage capability. An exclusive relay satellite with limited storage capacity and downlink communication bandwidth to Earth could be congested with huge amounts of return data from multiple sources on the lunar surface, resulting in low efficiency in the backhaul link. To address this issue, a network-coded forwarding scheme employing a Markov-decision-assisted bundle aggregation for a Halo-orbit Earth-lunar DTN is proposed in this article. Specifically, a network-coding-enabled store-and-forward scheme is designed for the downlink relay delivery in the L2-point Halo orbit using a two-priority bundle-aggregation mechanism. A size-optimal bundle slicing-aggregation algorithm is developed for the two-source network coding scheme using the Markov decision algorithm. Simulation results demonstrate that the proposed mechanism exhibits better performance than existing delivery schemes in reducing end-to-end delivery latency. Thus, the throughput can be improved, and the arrival rate of high-priority bundles can be guaranteed.