European Space Agency

CONSTELLATION - Simulator for managing interference between NGSO constellations and GSO


The objectives of this activity are:

  1. to define realistic scenarios between NGSO constellations and GSO/other NGSO systems, to be analysed with simulations
  2. to design and develop a software tool that shall be able to:
    • devise technologies and techniques for enabling the coexistence of NGSO and GSO satellite networks in the same frequency bands;
    • devise technologies and techniques for enabling the coexistence of several NGSO satellite networks in the same frequency bands;
    • assess the inter-system interference coming from, and affecting a given NGSO satellite network. Adjacent systems being interfered or interfering into the considered NGSO satellite network could be GSO or NGSO;
    • assess the effectiveness of interference mitigation techniques, in order to enable the coexistence of different systems
    • draft guidelines, that can be used in international forums, and that can help NGSO providers design GSO-compliant systems and coordinate with other NGSO providers 

(Airbus is credited for the picture)


The project aims at providing a tool capable of analysing realistic scenarios in terms of interference against GSO satellites and other NGSO systems. The challenge is to implement a tool (including the capability of using different mitigation techniques) that can be reused to completely design a constellation of up 5000 satellites  and check the interference level over up to 1000000 points on Earth in a reasonable time.


The modular approach of the tool is a crucial requirement. In fact, even if the tool is used, in the project, to analyse a limited number of well-defined scenarios, its modularity allows to be reused and applied for future studies. In principle the user will have the basics that allow him to design his system, in terms of orbit altitude, number of satellites, orbital planes, phasing of the satellites, beam type, number of beams, operational strategy (mitigation techniques), and perform the relevant analysis. Moreover, the check for the interference can be conducted over up to 1000000 points on Earth in a reasonable time.


The tool aims at helping research and development activities related to NGSO satellite systems design . The capabilities of the tool that support the benefit, and that also set challenges, are:

  1. analysis of a NGSO system with up to 5000 satellites
  2. choice of the number and type of satellites beams (fixed, steerable)
  3. choice of the antenna patterns, both on ground and space
  4. interference computation over up to 1000000 points on Earth
  5. generation of inputs compliant with ITU software to verify the EPFD requirements

System Architecture

The tool is composed of: 

  1. a GUI for the user to setup the scenario to be analysed. Such GUI is optimized for the setup of constellation of satellites
  2. a core processing for the computation of the interference metrics, such as EPFD. Given the challenging requirements on the computational time, the core does not have any GUI.
  3. a GUI for the visualization of the results

 Although the tool is implemented to analyse specific scenarios that are defined at the beginning of the project, the modular approach of the software will make it reusable for different scenarios. Every step in the process has a different module:

  1. setup of the scenario
  2. analysis of geometry of the systems, with computation of the active links
  3. computation of the link budget for the active links
  4. computation of interference level and metrics
  5. definition of mitigation techniques


The phases of the project are the following:

  1. Definition of the scenarios to be analysed
  2. Design of the tool
  3. Implementation of the tool
  4. Testing of the tool
  5. Analysis of the scenarios using the tool, including optimization of the results using the mitigation techniques
  6. Definition of guidelines according to the results of the simulations

The milestones of the project are such that every step is reviewed carefully:

  1. Design Review
  2. Implementation Review
  3. Test Review
  4. Conclusion of the study

Current status

Currently the study is in the first phase. Scenarios are being analysed and detailed, in terms of geometry of the constellations, orbital parameters, antenna patterns and mitigation techniques to be used. At the same time, the preliminary scenarios characteristics are being translated in terms of design, to meet the challenging requirements.

Status date

Wednesday, October 30, 2019 - 07:09