PAGE CONTENTS
Objectives
The main objectives of the project is to develop a detailed simulation tool for complex RF payload front-ends within a system simulator.
The tool has to allow to:
- Model a large variety of signals, including most of those specified by currently popular satellite physical layer standards (e.g. DVB-S2, DVB-RCS, DVB-SH),
- Measure the effects of the payload on such signals by evaluating end-to-end performance metrics (C/(N+I), BER/FER, EVM) over specific points in the coverage area or even over the whole satellite coverage area and, if necessary along the payload chain.
In particular, the tool allows for a detailed modelling of various antenna architectures and associated beam-forming networks (e.g. active, semi-active), in combination with the rest of payload. Traditional design approaches typically address the performance assessment for the antenna system separately from that of other payload elements of the RF front-end.
During the project, a few complex RF-front-end architectures (featuring either Single-Feed-Per-Beam Antennas, or Array Fed Reflectors Antennas or Direct Radiating Array Antennas) were defined for SW validation purposes.
Challenges
The tool is a time-domain waveform simulator able to evaluate the payload impact on the end-to-end signal degradation and on the overall system performance. Time-domain simulation of signal waveforms traversing the whole payload, including antennas (characterized through their far-field radiation properties) is performed.
The tool is able to evaluate the end-to-end effects of the payload on digital signals in terms of FER/BER, including the effects of antenna and advanced front-end architectures (e.g. active antennas, MPAs, etc.). In alternative to FER/BER evaluation the tool is able to evaluate SNIR degradation due to the payload (antenna included) which may shorten simulation time in some conditions.
The payload simulation tool provides an efficient interface with complementary external tools (e.g. antenna tools) to generate the Far Field Electromagnetic channel matrix covering the interesting ground area and considering all the elements (beams or feeds) of the considered antenna.
Plan
The project plan is divided into the following phases:
- Definition Phase, including the tasks:
- Assessment of simulator requirements,
- Identification of Reference Payload Architectures,
- Assessment of available state-of the-art software to be used as basis for the simulation tool,
- Definition of missing modeling methodologies, on the basis of a review of the classical methods already known and employed in industry,
- Definition of simulator architecture,
- Definition of reference payload architectures to be used for validation,
- Definition of validation Plan.
- Development Phase including the tasks:
- Development of the elementary building blocks and their integration with the GUI,
- Integration of software building blocks,
- Simulator validation with respect to the selected reference,
- Payload Architectures and the final validation plan,
- Support and training to Agency staff.
Current Status
The project was completed in May 2012.
The final conclusions are:
- The payload simulation tool has been implemented after a thorough assessment of the requirements and the used methodologies,
- The tool has been designed having in mind a fully modular approach, that will allow to add new simulation blocks to the building block library in a very easy way allowing, for instance the addition of new communication standards as soon as they are defined,
- The choice of converting the GUI scenario in a script has proved successful, because in this way the user can also directly use the powerful script language capabilities for building very complex scenario capable to cope with large payloads (e.g. high number of beams, amplifiers, feeds, etc.) representative of advanced multi-beam missions (e.g. hundreds of beams),
- The simulation durations and needed memory/processing resources have been proved to be comparable or competitive with the available commercial waveform simulators,
- The validation process, was performed using real measured data from different defined RF-front-end and antenna architectures (including Single-Feed-Per-Beam, Array Fed Reflectors, and Direct Radiating Arrays) used as reference payload architectures, was successful and encourages the use of the tool in real complex payload projects.
