Iterat ive decoding is a widely used technique in modern communications systems. The Low Density Parity Check (LDPC) codes of Gallager were the earliest codes for which iterat ive decoding techniques were dēned. These codes along with a simple iterat ive decoding algorithm were int roduced in the r̄st part of this art icle. Here we describe a probabilist ic iterat ive decoding scheme, also propo...

A pipeline decoder for woven convolutional codes (WCCs) is introduced. The decoding is performed iteratively by shifting a window over the received sequence. For the symbol–by–symbol a posteriori (s/s– APP) decoding of convolutional code segments, a windowed version of the BCJR algorithm is applied. This pipeline concept allows a trade–off between decoding delay, decoding complexity, and perfor...

We propose an algorithm for finding the optimal decoder activation order in a system with more than two concatenated codes. Optimality is defined as the order that yields convergence using the lowest computational complexity, guided by the extrinsic information transfer (EXIT) charts of the component codes. We also describe how the convergence threshold for the system can be visualized by combi...

Date Approved _________________ iii To my beloved wife Túria, with my endless gratitude, love and admiration. iv Acknowledgments First, I would like to thank Dr. John Barry for his guidance during my stay at Georgia Tech. His very clear and objective view of technical matters, as well as his deep insights, have influenced a lot my view of research in telecommunications, and hopefully made this ...

Introduction: Multilevel coding (MLC) was proposed by Imai and Hirawaki [1] as a bandwidth-efficient coded modulation scheme designed for protecting each bit of a non-binary symbol with the aid of binary codes, while maintaining different target bit error rates (BERs). Parallel independent decoding (PID) [2] is employed as an efficient decoding strategy with reduced decoding delay, where there ...

We investigate iterative decoding and channel estimation for multiple-access channels. Results are obtained concerning the fixed points of such iterations. I. Iterative Receiver Principle In [1] an iterative receiver was proposed for the linear multiple access channel. We now consider an approach for integration of channel estimation into this technique whereby we use the a-posteriori probabili...

Ever since the seminal paper [6] there has been a flurry on activity on channel coding systems with antennas and multiple input and output (MIMO) for emit and receive through a double coding in time and space [8]. This is in particular of crucial importance in downlink mobile communications. In view of recent advances in channel coding due to iterative decoding (turbocodes and low density parit...

With wide applications of Turbo Principle in communications engineering, the EXIT Charts (Extrinsic Information Transfer Charts) has been a powerful tool to visualize the convergence behavior of iterative decoding process based on mutual information. Within this report, an introduction to EXIT Charts, its background, properties and applications are presented to allow the audience be familiar wi...

A low-complexity low density parity check (LDPC) coded bit-interleaved coded modulation with iterative decoding (BICM-ID) scheme with orthogonal modulations is proposed. With a novel mapping strategy of coded bits to symbols, the proposed scheme is equivalent to a generalised LDPC code with Hadamard constraints and thus orthogonal demodulation can be merged into the iterative LDPC decoding proc...

An algorithm of improving the performance of iterative decoding on perpendicular magnetic recording is presented. This algorithm follows on the authors’ previous works on the parallel and serial concatenated turbo codes and low-density parity-check codes. The application of this algorithm with signalto-noise ratio mismatch technique shows promising results in the presence of media noise. We als...