CGR-BF: An efficient contact utilization scheme for predictable deep space Delay Tolerant Network

In this paper we propose a scheme that uses the fragmentation scheme of bundle protocol for efficient utilization of contacts between nodes so as to increase the goodput in deep space networks. The node (e.g., planets/satellites/Orbiters) positions in deep space are predictable and messages are transmitted from one node to the other in a store-and-forward mode whenever these nodes are in contact with each other. Contact Graph Routing (CGR) has been proposed for interplanetary networks due to its delay tolerant nature and characteristics. The CGR chooses a single path between a source and a destination node to achieve the best delivery time of a bundle. However, the contacts that cannot transmit one complete bundle or have some leftover capacity after transmitting one or more complete bundles are ignored here. This leads to wastage of deep space transmission opportunities which are significant. In this paper, we propose a scheme for utilizing these contacts efficiently by fragmenting the bundles wherever possible. The bundle fragments are then routed to the destination using multiple paths. Simulation studies show that CGR-BF efficiently exploits the network's bandwidth and substantially increases the goodput incurring minimum overhead compared to that of the CGR where fixed size bundles are used.