Extrinsic Information Transfer Charts as a Design Tool for Inerative Processors

Iterative processors have become an important building block of communications receivers. This talk gives an introduction to a design tool that has proven rather accurate in predicting the behavior of such devices. The tool, called the extrinsic information transfer (EXIT) chart, was developed by taking an engineering "transfer function" approach to analysis. We illustrate the use of an EXIT chart for turbo codes, and show how it guides the choice and design of codes for other problems such as modulation, detection, equalization, and so forth. Design examples for multi-antenna communication are presented. We further outline theoretical progress on understanding why the tool works so well, and how one might improve its predictions.