Receiver for FTN signaling in non-linear channel: Joint channel estimation and synchronization

In order to increase the capacity of future satellite communication systems, faster-than-Nyquist (FTN) signaling is increasingly considered. The gain in terms of transmission rate is obtained at the price of significant intersymbol interference (ISI) introduction. To benefit from an improved spectral efficiency (SE), many iterative detectors have already been investigated, demonstrating the interest of such a waveform in linear and non linear channels. A thorny point in FTN signaling remains its synchronization since the usual algorithms considered in the DVB-S2X standard cannot be applied on this waveform without significant loss on the performance. This paper proposes a synchronization scheme for FTN signaling in a satellite context. It is based on a Volterra decomposition of the received signal in order to fit both with linearized and non-linearized amplifiers which can be found in the satellite payload. Two steps, initialization and tracking are considered, based on training sequences fulfilling the DVB-S2Xs frames requirements. After start of sequence detection and frequency offset correction, the channel estimation is used for time offset issue in the two proposed schemes. Their performance are compared to the performance of a perfect synchronized detection.