Design of RC-LDPC codes and its application for shallow water acoustic communications

Abstract

According to fast temporal variations shallow water acoustic (SWA) channels, dynamic channel coding, adjusted according to different ocean channel characteristics, should be desired in the design of practical error control SWA communication system. In this paper, we propose a dynamic channel coding scheme where rate-compatible (RC) LDPC (RC-LDPC) codes is adopted as an example to improve the system reliability for SWA communications. Based on the automatic repeat request (ARQ) mechanism, the proposed SWA system consists of three important preprocessing: channel state information (CSI) estimator, signal-to-noise ratio (SNR) estimator and RC-LDPC pattern. For ARQ-SWA system, we firstly derive the throughput of the ARQ-SWA system adopting RC-LDPC codes. The SWA channel model profile is then given, and the description of RC-LDPC codes is also presented. The RC-LDPC performance patterns, effects of different mother code design and throughput analysis of the system are also discussed via simulation. It is shown that, RC-LDPC codes constructed using extending demonstrates good performances with wide range of rates in SWA channels. Furthermore, combining Quangang Xiaocuo harbor SWA channel data, coding rate distributions of RC-LDPC codes in different SNR at BER below 10 -4 are investigated.