Synchronization for Variable Data Rate LEO Direct-to-Earth Optical Links

The recent developments in the field of direct-to-Earth (DTE) for low-Earth-orbit (LEO) satellite optical links have shown the potential benefits of on-off-keying-based communications with the variable data rate (VDR) technique, in contrast to the traditional constant data rate (CDR) approach. In this paper, relevant link level aspects are analyzed, namely: time, frame, and amplitude synchronization, showing that reliable and performing techniques allow to fully exploit the advantages offered by the VDR strategy.