Iterative Vector Tracking of Turbo- or LDPC- Coded High-level Constellations on a Nonlinear Satellite Channel

Interactive multimedia wideband satellite services will require the adoption of Turbo or Low-Density Parity-Check (LDPC) coded spectrally-efficient high-level modulation techniques in future satellite transmission standards. In such a scenario nonlinear distortion caused by the on-board (nonlinear) high-power amplifier is quite a concern, so that countermeasures are to be properly adopted. The aim of this paper is to investigate the feasibility to use a low-complexity blind channel estimation algorithm, derived by means of the Expectation-Maximization (EM) approach, which makes iterative use of soft decisions provided by the SISO decoders within the overall decoding scheme. The performance of the proposed estimation scheme is evaluated over a nonlinear satellite channel for both Turbo and LDPC codes and compared with that of a conventional DA (Data Aided) vector tracker.