Trellis Shaping Techniques for Satellite Telecommunication Systems

摘要

In recent years, satellite overlay networks have shown their potential for delivering multimedia content both to rural and urban environments. In the latter case, the adoption of terrestrial Intermediate Module Repeaters (IMRs) is in order to close the link in Non-Line-of-Sight propagation conditions, causing a severe increase of multipath propagation and consequent linear distortion, adding to the intrinsic non linear distortion of satellite links. Whenever the propagation channel for the user receiving the data can be known with good approximation at the transmitter, the application of precoding techniques can be considered as a feasible solution to counter channel dispersion. In this paper, trellis shaping (the combination of Tomlinson-Harashima precoding and signal shaping) is used along with predistortion techniques to increase the resilience to channel dispersion and non-linear distortion. Numerical simulations allow us to assess the robustness to nonlinear distortion of trellis-shaped signals. Different optimization goals are pursued by means of different trellis shaping metrics, including several novel ones. Improvements in performance are achieved with respect to the unshaped case.