EXIT Charts for Nonbinary LDPC Code Design

This article explains how to use EXIT charts to design nonbinary LDPC codes with MATLAB source code. The implementation applies EXIT Method no. 2 from our paper "Design and Analysis of Nonbinary LDPC Codes for Arbitrary Discrete-Memoryless Channels," originally presented at ISIT 2005. The method enables the design of sophisticated nonbinary LDPC codes tailored for various discrete-memoryless channels. The MATLAB implementation includes systematic procedures for constructing EXIT charts, analyzing code performance, and optimizing degree distributions. Key functions handle iterative decoding analysis, mutual information calculations, and convergence tracking between variable and check nodes. We provide detailed implementation steps and comprehensive code comments to facilitate understanding and application of this source code. The algorithm features modular design with separate functions for channel modeling, EXIT curve generation, and code optimization, allowing researchers to easily adapt the code for specific channel conditions and code parameters while ensuring correctness and effectiveness of the resulting LDPC codes.