Communications architecture for space-based sensor networks

Numerous planned and proposed future space exploration missions employ multiple spacecraft that perform multipoint sensing. Distributed space-based sensing missions can significantly benefit from incorporation of cross-link communications capabilities, thereby forming space-based networks, by enabling continuous access to any/all spacecraft via a single ground contact, real-time coordinated observations, and autonomous in situ processing within a spatial neighborhood of spacecraft. We present a communications architecture for space-based sensor networks. Because of the large inter-spacecraft distances, directional antennas are used, with a single half-duplex transceiver per spacecraft to achieve low cost. Orbital motion induces a dynamic albeit predictable geometry (and topology) among the spacecraft. Primary offered traffic is sensor telemetry destined to the Earth ground station, although other traffic patterns are also treated. We present a technique that derives the link activation schedule (transmit/receive mode and communications neighbor selection) and routes used for efficient traffic relay through the network, leveraging the Florens and McEliece algorithm for tree networks. An illustrative example is presented, and throughput and latency performance are evaluated. An extension to the networking method is described that is traffic adaptive.