High-Throughput Distributed Spacecraft Network: architecture and multiple access technologies
BBN Technologies (BBN), under a task for the Space Communications Project, designed the High-Throughput Distributed Spacecraft Network, or Hi-DSN. It provides a self-forming vertically integrated network infrastructure for establishing and maintaining high-throughput multi-hop communications among spacecraft operating in diverse orbits. The Hi-DSN integrates the predictability of orbital movement to establish and maintain cross-links and multi-hop routes, ad hoc networking capabilities to autonomously discover ''new'' neighbors, null-steered spatial multiplexing to maximize re-use of the allocated spectrum, and variable-rate cross-links to maximize network connectivity under large inter-spacecraft distances and distance differentials. The Hi-DSN architecture is hierarchical and can be extended to provide dynamic ''terminal affiliation and handoff'' for transferring data from spacecraft to aircraft and spacecraft to ground terminals and sensors. The descriptions included in this paper focus on the aspects of the architecture that are relevant for the planet vicinity networks, part of NASA's future space-based internetwork communications infrastructure, and specifically on the enabling physical-layer, medium-access control (MAC) layer and sub-network level (i.e., below IP) technologies required to create a scalable communications infrastructure that can be used to extend the (terrestrial) Internet to space. In a follow-on development for NASA, BBN is designing the architectural extensions and developing the protocols to extend Internet VPNs to space, or SpaceVPNs.