High performance coded modulation and receiver design for the satellite and terrestrial channel.

摘要

In the nonlinear satellite channel, bandwidth and power efficient transmission techniques are required, along with compensation for nonlinear distortion. Amplifier nonlinearity combined with pulse shaping results in intersymbol interference (ISI). Here we propose and examine the performance of several equalization techniques with coded modulation systems which are capable of achieving spectral efficiencies greater than 2 bits/sec/Hz.;First, we derive the Maximum Likelihood sequence detector for a Volterra channel model, and compare its structure with receivers based on alternative nonlinear state model. As a suboptimal solution to this problem we assess the performance of Volterra and linear equalizer, and also ISI canceller for uncoded and trellis coded modulation (TCM).;For (noninterleaved) TCM over the satellite channel, combined equalization and decoding is possible. We propose a novel reduced complexity Maximum Likelihood decoder for the Volterra channel model. Performance analysis for the proposed system is also given. Both the analysis and simulation results confirm the significant performance improvement.;The application of turbo code to the satellite channel is also possible. We assess the performance of TTCM (turbo TCM) and propose a novel combined equalization and decoding scheme for TTCM. Performance comparison with the conventional (separate) Volterra type equalizer and the data predistorter is presented.;As an extension of our research, we investigate an advanced receiver structure for the terrestrial DTV (digital TV) channel. Among several issues in the channel, error propagation problem in DFE (decision feedback equalizer) is mainly covered in this thesis. We propose a novel method which combines soft input DFE and SOVA TCM decoder to mitigate error propagation in DFE. The proposed scheme gives significant performance gain over the conventional DFE and TCM decoding scheme.