EXIT Chart Based System Design for Iterative Source-Channel Decoding with Fixed-Length Codes

Laurent Schmalen

doi:10.1109/TCOMM.2011.062311.090019

Return

EXIT Chart Based System Design for Iterative Source-Channel Decoding with Fixed-Length Codes

2011-09-01

PRE

Laurent Schmalen *

Peter Vary

DOI：10.1109/TCOMM.2011.062311.090019

Original

Original request for help

Save

Abstract

En 中文

Audio-visual source encoders for digital wireless communications extract parameter sets on a frame-by-frame basis. Due to delay and complexity constraints these parameters exhibit some residual redundancy which manifests itself in non-uniform parameter distributions and intra-as well as interframe correlation. This residual redundancy can be exploited by iterative source-channel decoding (ISCD) to improve the robustness against impairments from the channel. In the design process of ISCD systems the well known EXIT charts play a key role. However, in case of inter-frame parameter correlation, the classic EXIT charts do not provide reliable bounds for predicting the convergence behavior of ISCD. We explain the reasons for the so-called overshooting effect and propose a novel extension to the EXIT chart computation which provide significantly better bounds for the decoding trajectories. Four advanced ISCD system configurations are proposed and investigated using the benefits of the improved EXIT chart based system design. These configurations include regular and irregular redundant index assignments. In addition, we incorporate unequal error protection in the optimization of irregular index assignments. We show how to realize a versatile multi-mode ISCD scheme which operates close to the theoretical limit.

Keywords:

Iterative source-channel decoding (ISCD)

soft decision source decoding (SDSD)

turbo principle

EXIT chart

AI Summary

Key information extracted from the uploaded paper, including a brief overview, abstract, background, key highlights, visual analysis, and future outlook.