I-CUBE - Inmarsat-CUBEsat

I-CUBE project  has been funded by Inmarsat UK. In the framework of this project it has been analyzed and evaluated the viability of using Ultra-Narrow-Band (UNB) systems in the return link of LEO constellations. This study has also characterized the satellite channel, the description of the physical layer, the access scheme of a UNB communication system and the computation of system-level simulation. Especial emphasis has been given to the characterization of the Doppler effects, which include the Doppler shift and the Doppler rate, as well as their impact on the system performance and the synchronization procedure. The project outcome has been a system-level simulator that computes the number of users that can be detected for different traffic conditions and demodulation probabilities. In order to increase the throughput of the UNB system, it has been considered the capture effect. By doing so, it is possible to detect the desired user although it be interfered by another one. Finally, the study has also provided practical implementation aspects that arise in LEO communication systems. In this regard, most of the work has been devoted to investigate the frame detection as well as the coarse and fine carrier frequency offset estimation.