Bulletin of Electrical Engineering and Informatics Vol. 14, No. 1, February 2025, pp. 338~356 ISSN: 2302-9285, DOI: 10.11591/eei.v14i1.8260  338 Journal homepage: http://beei.org EXIT chart analysis of regular and irregular LDPC convolutional codes on AWGN channel Oulfa Laouar, Imed Amamra, Nadir Derouiche Laboratory LRES ICT Team, Department of Electrical Engineering, Faculty of Sciences and Technology, University of 20 th August 1955, Skikda, Algeria Article Info ABSTRACT Article history: Received Feb 2, 2024 Revised Oct 1, 2024 Accepted Oct 17, 2024 Low-density parity-check (LDPC) codes are widely recognized for their excellent forward error correction, near-Shannon-limit performance, and support for high data rates with effective hardware parallelization. Their convolutional counterpart, LDPC convolutional codes (LDPC-CCs), offer additional advantages such as variable codeword lengths, unlimited parity- check matrices, and simpler encoding and decoding. These features make LDPC-CCs particularly suitable for practical implementations with varying channel conditions and data frame sizes. This paper investigates the performance of LDPC-CCs using the extrinsic information transfer (EXIT) chart, a graphical tool for analyzing iterative decoding. EXIT charts visualize mutual information exchange and help predict convergence behavior, estimate performance thresholds, and optimize code design. Starting with the EXIT chart principles for LDPC codes, we derived the mutual information functions for variable and check nodes in regular and irregular LDPC-CC tanner graphs. This involved adapting existing EXIT functions to the periodic parity-check matrix of LDPC-CCs. We compare regular and irregular LDPC-CC constructions, examining the impact of degree distributions and the number of periods in the parity-check matrix on convergence behavior. Our simulations show that irregular LDPC-CCs consistently outperform regular ones, and the EXIT chart analysis confirms that LDPC-CCs demonstrate superior bit error rate (BER) performance compared to equivalent LDPC block codes. Keywords: Convergence behavior Extrinsic information transfer chart Iterative decoding Low-density parity-check codes Low-density parity-check convolutional codes This is an open access article under the CC BY-SA license. Corresponding Author: Oulfa Laouar Laboratory LRES ICT Team, Department of Electrical Engineering, Faculty of Sciences and Technology University of 20 th August 1955 Skikda, Algeria Email: o.laouar@univ-skikda.dz 1. INTRODUCTION One of the most extensively used techniques for ensuring reliable data transmission in communication networks is error correction codes [1]. Due to their excellent error-correction performance close to the Shannon limit and low complexity decoding algorithms, an advanced class of channel encoding scheme, is the low-density parity-check (LDPC) code. These codes have gained widespread attention in the 1990s after being overlooked for over 35 years, where the researchers community was attracted to analyze and design these codes [2] using message-passing (MP) decoding algorithm [3]. The improvement in the performance of LDPC codes was observed when irregular codes were derived from regular ones [4], defined in terms of the distribution of variable and check nodes degrees introduced by a graphical representation [5] known as the tanner graph.