Juan A. Fraire

Researcher in Space Networking and Informatics

Inria CONICET Saarland University

Publications Journal article · Delay-tolerant networks · 2021

On the scalability of battery-aware contact plan design for LEO satellite constellations

Juan A. Fraire, Carsten Gerstacker, Holger Hermanns, Gilles Nies, Morten Bisgaard, and Kristian Bay

Wiley International Journal of Satellite Communications and Networking, vol. 39, no. 2, pp. 193–204, 2021

Publisher’s version

ShareLinkedInXBlueskyEmail

Abstract

Summary

Size and weight limitations of low‐Earth orbit (LEO) small satellites make their operation rest on a fine balance between solar power infeed and power demands of supporting communication technologies, buffered by on‐board battery storage. As a result, the problem of planning battery‐powered intersatellite communication is a very difficult one. Nevertheless, there is a growing trend toward constellations and mega‐constellations that are to be managed using sophisticated software support. In earlier work, we have discussed how the effective construction of contact plans in delay‐tolerant satellite networking can profit from a refined model of the on‐board battery behavior. This paper presents a profound study of the scalability of the approach and discusses how to tailor it to the needs arising in the management of mega‐constellations, together with a variety of improvements to the base approach. Results show that efficient mega‐constellation operations are compromised, encouraging further research on the area.

Cite

DOI 10.1002/sat.1374

BibTeX
@article{DBLP:journals/ijscn/FraireGHNBB21,
  author  = {Juan A. Fraire and Carsten Gerstacker and Holger Hermanns and Gilles Nies and Morten Bisgaard and Kristian Bay},
  title   = {On the scalability of battery-aware contact plan design for {LEO} satellite constellations},
  journal = {Wiley International Journal of Satellite Communications and Networking},
  volume  = {39},
  number  = {2},
  pages   = {193--204},
  year    = {2021},
  doi     = {10.1002/sat.1374}
}

More on delay-tolerant networks

  1. Routing in the Space Internet: A contact graph routing tutorial Juan A. Fraire, Olivier De Jonckère, and Scott C. Burleigh Elsevier Journal of Network and Computer Applications, 2021
    Abstract

    A Space Internet is possible, as long as the delay and disruption challenges imposed by the space environment are properly tackled. Because these conditions are not well addressed by terrestrial Internet, more capable Delay-Tolerant Networking (DTN) protocols and algorithms are being developed. In particular, the principles and techniques for routing among ground elements and spacecraft in near-Earth orbit and deep-space are enacted in the Contact Graph Routing (CGR) framework. CGR blends a set of non-trivial algorithm adaptations, space operations concepts, time-dynamic scheduling, and specific graph models. The complexity of that framework suggests a need for a focused discussion to facilitate its direct and correct apprehension. To this end, we present an in-depth tutorial that collects and organizes first-hand experience on researching, developing, implementing, and standardizing CGR. Content is laid out in a structure that considers the planning, route search and management, and forwarding phases bridging ground and space domains. We rely on intuitive graphical examples, supporting code material, and references to flight-grade CGR implementations details where pertinent. We hope this tutorial will serve as a valuable resource for engineers and that researchers can also apply the insights presented here to topics in DTN research.

  2. Ring Road Networks: Access for Anyone Marius Feldmann, Juan A. Fraire, Felix Walter, and Scott C. Burleigh IEEE Communications Magazine, 2022
    Abstract

    Several billion people currently lack reliable access to the Internet and thus to a tremendous source of knowledge. In this article, we describe a field-tested communication approach combining CubeSat platforms and delay-tolerant networking (DTN) solutions to provide asynchronous connectivity to populations and regions that are underserved by the Internet. The resulting class of networks is known as ring road networks (RRNs), a networking approach that is built on technology developed for the construction of a solar system Internet. The necessary self-sufficiency of DTN nodes enables network access to be deployed incrementally at low cost, supporting communities that cannot be profitably served by Internet satellite constellations. We present the RRN architecture and evaluate the expected performance by means of simulations. Based on the latter, we discuss µD3TN: a lightweight and open source DTN protocol stack for RRNs and other DTN classes. µD3TN has been flight-tested in ESA's OPS-SAT in low Earth orbit during December 2020 and May 2021. This work discusses the experiment results as we validated the RRN approach in concrete application use cases. The reported outcomes motivate a new application domain.

  3. Autonomous Max-Flow Interplanetary Laser Link Scheduling for Martian Exploration Jason Gerard, Andre Ibrahim, Juan A. Fraire, and Sandra Céspedes IEEE International Conference on Wireless for Space and Extreme Environments (WiSEE), 2024
    Abstract

    New communication technologies like delay and disruption-tolerant networking (DTN) and free-space laser communications are being developed to handle massive planetary telemetry data. However, existing infrastructure cannot meet the scalability and autonomy demands of future space missions, resulting in 95% of data left on the mission planet. Manual scheduling of deep-space laser transmissions by operators is inefficient and error-prone, limiting mission parallelization, while autonomous scheduling, though promising, may limit optimal network routes reducing the network capacity. We hypothesize that autonomously scheduling contact opportunities will enable acquisition, tracking, and pointing (ATP) for free-space lasers and increase the capacity of interplanetary backhaul networks. In this work, we propose the Laser Link Scheduler (LLS), which combines a novel max-flow network capacity model and a decision-making algorithm for contact selection. We define a series of deep-space communication scenarios where data is collected from orbiters around Mars and backhauled to Earth. LLS is evaluated in simulations using contact plans generated based on realistic conditions and orbital dynamics. Our results confirm that autonomous contact scheduling increases network capacity by 1.5-2x, reducing operational costs and enabling highly parallel space exploration missions.