European Space Agency

SCNE - Satellite Constellation Network Emulator

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Objectives

Telecommunication Satellite systems are raising in complexity: new LEO constellation projects are under development, targeting not only low speed data collection or mobile communications, but also broadband and broadcast services. Mastering the cost of these constellations and at the same time being able to assess the offered Quality of Service is critical to secure the business case of the satellite operator. 

The objective of the SCNE project is to enable the study and assessment of protocol performances used in these new constellations, in particular routing protocols which may affect the end to end quality of service. The tool is based on a high end PC workstation and COTS orbital and network simulators which will be coupled to facilitate the correlation of network and orbital events. 

The project activities include the design of a library of satellite network elements (e.g. routers, interfaces), the development of a Human Computer Interface and an orchestrator in charge of the coordination of the orbital and network simulation. 

Two complete scenarios will be developed to validate the tool on realistic cases.

 

Challenges

The Co-simulation approach taken for the SCNE raises several challenges: 

Interfacing of two completely different simulation approaches: This is not limited to the exchange of information (e.g. through files) but also to the synchronisation of the two processes for real time and faster than real time play back. 

Code optimisation to enable to run complex simulations (involving hundreds of mobile network equipment and user terminals). 

Design of the Human Computer Interface which shall enable the definition of complex scenarios (including orbital and network models), and the analysis of the performance of a given constellation.

Benefits

The benefits of the SCNE is to enable the simulation of a complete constellations and joint investigation of physical layer aspects (visibility, BER) and higher layer protocols (IP routing, TCP, UDP). This is particularly important on non GEO constellation where platform and payload must be jointly optimised. This novel co-simulation approach goes beyond traditional simulation tools which handle either orbital or network aspects, with limited interfacing and coupling between the two. 

The SCNE uses proven COTS simulators for best performances and uses a dedicated orchestrator to control the automatic execution of the two simulations or of an orbital simulation and network emulation in parallel. 

A Human Computer Interface enables to implement user defined constellations and control the simulation. Different real time views and analysis reports are available to optimize the constellation and assess its performances.

Definition of user defined models of networking elements and interfaces is also possible to increase the accuracy of the simulation. 

Two example scenarios and a user manual facilitate the utilisation of the tool in the satellite community.

Features

Based on a co-simulation approach that enables the modelling of complete satellite constellations including orbital and network aspects. 

Real Time, Faster/Slower than real time playback of simulations 

Off line analysis of end to end performances thanks to text and graphic reports. 

Possibility to run in full simulation mode, mixed simulation / emulation mode or run orbital and network simulation separately. 

Complete Human Computer Interface, including Graphical User Interface, Command Line Interface (for scripting) and Programming interface (C++) 

Includes two complete scenarios. Possibility to implement a user defined constellation and proprietary network models. 

Used of proven COTS simulators:

  • Full orbital simulation capability based on STK Professional module.
  • Full layer 1 communication modelling capability based on STK Communication module.
  • Open Simulation environment for the study of networking protocols based on ns-3.
  • Remote control of STK based on STK integration module 

Runs on High End PC Work Station with 1 or 2 displays. Accessible on-line for registered users. 

Simulation capabilities

  • 300 network nodes
  • 50 users

System Architecture

The SCNE hardware is composed of a generic High End PC workstation, with one or two displays. 

The SCNE software is based on a combination of proven COTS and dedicated software. 

COTS modules include:

  • STK Orbital simulation module
  • STK Communication module
  • Ns-3 even simulator and general library
  • STK integration module 

Dedicated modules include:

  • Human Computer Interface (GUI+CLI+API)
  • Orchestrator
  • Ns-3 satellite library
  • 2 satellite constellation scenarios 

The HCI is used to load the orbital and network scenarios. The orbital simulation is then run, providing links characteristics of all the possible links between satellites, users and gateways. Then the network simulator is run, providing information on network usage via performance reports.

  • The network simulator may be run separately from the orbital simulator to optimise the network aspects
  • A synchronous playback mode facilitates the correlation of network and orbital events.

Plan

The project has a duration of 22 month, starting in September 2018 and ending in July 2020. 

The project is composed of 6 phases :

  • Requirement Specification
  • High Level Design
  • Detailed Design
  • Implementation
  • Integration
  • Validation 

There are 6 project milestones:

  • KOM (T0)
  • SRR (T0+3)
  • PDR (T0+5)
  • CDR (T0+10)
  • AR (T0+19)
  • FR (T0+22) 

The deliverables are the SCNE (hardware + software) as well as complete documentation and user manual.

Current status

The project started on September 3rd. A stakeholder consultation is organized from September 28th to October 28th to better define the user requirements and start the technical specification. 

Contacts

ESA Contacts

Status date

Tuesday, October 23, 2018 - 10:20