APTICA, in collaboration with the Radiation Group of the Signals, Systems and Radiocommunications Department (SSR) of the Polytechnic University of Madrid (UPM) and the Communications Networks Group of the Telematics Engineering Department of the Carlos III University of Madrid (UC3M), has been involved in the development of a tool designed to evaluate and validate the performance of communications systems and protocols for modern satellite constellations.

This collaboration has been developed within the framework of the R&D&I project VIRGOSAT (VIRtual control system for the GOvernment of mega-SATellite constellations), a project carried out thanks to funding from private investors.

The collaboration between the three entities has resulted in the development of an innovative simulation and emulation tool, termed LOOM (Low Orbit Operational network eMulator). This tool facilitates the generation of a virtual environment for the distributed communications network of a satellite constellation. This tool can be regarded as the digital twin of the communications network of a satellite platform, with the purpose of facilitating decision-making for satellite operators. It assists in constellation design, evaluates and optimises routing strategies, and allows for the analysis of the feasibility of services and use cases in advance.

The utilisation of Low-Earth Orbit (LEO) satellites in the formation of Mega-Constellation Networks (MCNs) has witnessed a surge in recent times, with numerous projects demonstrating stability in both design and implementation phases. However, these constellations pose challenges due to two factors. Firstly, the large number of satellites involved, and secondly, the ad hoc nature of the interactions between satellites and ground stations, due to the continuous movement of satellites. It is imperative that MCNs exhibit resilience and adaptability to these challenges; consequently, the design of their topologies and the protocols governing them assumes paramount importance in achieving these objectives.

The LOOM initiative aspires to address these challenges by establishing a professional working environment conducive to the execution of evaluation tests for MCNs. To this end, the LOOM architecture is composed of two main modules: an orbital environment simulator capable of calculating the geometry of the operating environment, and the state and traffic of the network, and a network topology emulator that allows to evaluate the routing algorithms designed in a relevant environment, taking into account the constellation topology and the network traffic. The emulator considers the network satellites as programmable network nodes and uses the Network Manager’s SDN controller as the network scheduler. The results visualisation module, based on CESIUM, allows observation of the temporal evolution of the network status.

The system, once validated, permits the addition and removal of customers in accordance with service agreements, the management of traffic exchange, and the adaptation to topology changes caused by load or inter-satellite link failures. It also facilitates the establishment of different access satellite selection criteria, as well as the evaluation of specific contracts, such as link loading or minimum distance criteria. Furthermore, the system is capable of generating reports on the loading status of the satellites, as represented in the visualisation module. These reports illustrate network parameters such as loading data, computational consumption, routes between ground stations, and latencies.

The development of a functional prototype, validated in the laboratory (TRL 4), has been enabled by this research project, integrating the different LOOM components and demonstrating their joint operation. The project has also laid the foundations for a potentially marketable system in the coming years. This initiative will continue to progress towards higher TRLs of research development, continuing with the collaboration of the UPM and UC3M.

The project has been made possible by the following organisations: