PAGE CONTENTS
Objectives
The growing interest in multimedia fixed applications calls for the development of point-to-point satellite systems capable of providing high-speed links at a competitive price. In order to meet this goal, satellite systems need to significantly increase their overall throughput with respect to current state-of-art.
Future multimedia broadband satellite systems will thus rely on:
- Large number of beams,
- ACM techniques to counteract fading / interference.
This study was motivated by the need to investigate new techniques for capacity improvement. In particular, the use of satellite systems with large number of beams and operation at higher frequency makes the system performance interference limited. Hence, techniques which go beyond ACM in mitigating interference and improving system throughput were the objectives of this work.
The main objectives of the Phase I of the present study were the exploration of new Multi-User-Detection (MUD) techniques able to improve the spectral efficiency, and hence the system capacity, of future broadband satellite systems for fixed communications.
In particular, the proposed techniques shall provide further improvements with respect to state-art ACM-enabled systems. The reference system for the new techniques evaluation was a transparent multi-star satellite network operating at high frequency band (Ka or higher) and availing of an antenna system able to generate a large number of beams (about 100 or even more).
Also within the scope of this study was the preliminary investigation of the applicability to the mobile-satellite communication field of the techniques already proposed and investigated in the frame of applicability to fixed satellite systems. A further topic of investigation was the analysis of interference mitigation in the frame of a spread Aloha system.
In Phase II the main objective was the development of a SW tool able to make detailed performance assessment of the most attractive of the proposed solutions. Performance assessment was required to be done not only at physical layer level but also at system level.
Challenges
The most important issues addressed in the study were:
- The improvement of the FL of a multi-beam satellite system through the exploitation of precoding techniques at the GW side.
- The improvement of the RL of a multi-beam satellite system using a DVB-RCS like TDMA access. Preferred techniques for this scenario were the spatial MMSE processing, eventually followed by SIC (Successive Interference cancellation) or Iterative Interference Cancellation (IIC).
Plan
The work was divided into two Phases. Phase I had the main objective to list and then sort the most appropriate MUD techniques for next generation transparent broadband satellite systems based on multi-star topology. In particular different classes of solutions were to be found for the Forward-Link and the Reverse-Link of such systems.
Adaptations of some of these techniques to the mobile environment were also considered together with possible enhancement of the classical Spread Aloha technique. In Phase II the effort was directed toward a SW tool development aimed at an in-depth validation of some of the proposed techniques. A simulation campaign using the developed tool was finally performed.
Current Status
The project has been completed. A Final Report documenting some of the investigated techniques has been produced and the developed SW tool delivered to ESA.
