Non-linear distortion noise cancellation for satellite forward links.

In this paper, an iterative receiver that performs non-linear distortion noise cancellation is proposed for application at the user terminal in the DVB-S2X satellite forward link. The performance is assessed for a single-carrier time-division multiplexing (TDM) waveform with low carrier roll-off factors, e.g., down to 5 %, and high baud rates, e.g., up to 34 MBaud in a 36-MHz transponder, in accordance with a very-small-aperture terminal (VSAT) scenario. The satellite forward-link channel is comprehensively modelled, including the input multiplexing (IMUX) and output multiplexing (OMUX) filter responses at the satellite transponder, the non-linear travelling wave tube amplifier (TWTA) characteristics, and the phase noise at the user terminal. Modulation orders up to 256-level amplitude and phase-shift keying (APSK) are evaluated with low-density parity-check (LDPC) forward error correction (FEC). The improved receiver is compared to state-of-the-art compensation techniques, such as pre-distortion at transmitter and linear equalization at receiver. In the higher-baud-rate scenario, the improved receiver demonstrates a 5.2-dB increase of the energy efficiency at 32-APSK or up to 40% increase of the spectral efficiency. In the lower-baud-rate scenario, up to 1.8-dB increase of the energy efficiency at 256-APSK is presented.