CGR-SPI: A New Enhanced Contact Graph Routing for Multi-source Data Communication in Deep Space Network

The future deep space network will have more number of orbiters, landers, rovers and relay nodes than it has today. Consequently, the communication between the nodes will no longer be time specific or bandwidth specific and therefore, the data generated at different planetary regions might be forwarded using common interplanetary links and intermediate relay nodes. The Contact Graph Routing (CGR) chooses a single path between a source and a destination node to achieve the best delivery time of a bundle. In this paper, we first evaluate, through emulation, the performance of CGR where multiple sources in deep space generate data (bundles) which are transmitted to earth in several hops while competing for the limited bandwidth of interplanetary links. Due to the Earliest Delivery Time (EDT) used in CGR, it is possible that data might get chocked because of long queues encountered in intermediate nodes. Sharing the partial queue-length information among nearby nodes, we propose an improved routing scheme for forwarding bundles in deep space network. Simulation studies show that this modification of CGR significantly improves the throughput by efficiently exploiting the deep space network's available bandwidth.