Performance Analysis of Protograph-based LDPC Codes with Spatial Diversity

TL;DR

This paper evaluates the performance of protograph-based LDPC codes with spatial diversity in wireless systems, introducing a modified PEXIT algorithm to analyze thresholds and comparing various codes through simulations.

Contribution

It proposes a modified PEXIT algorithm for threshold analysis and compares the performance of different protograph LDPC codes in SIMO systems.

Findings

Irregular LDPC codes perform best at low SNR.

AR3A code outperforms others at high SNR.

Diversity order significantly impacts code performance.

Abstract

In wireless communications, spatial diversity techniques, such as space-time block code (STBC) and single-input multiple-output (SIMO), are employed to strengthen the robustness of the transmitted signal against channel fading. This paper studies the performance of protograph-based low-density parity-check (LDPC) codes with receive antenna diversity. We first propose a modified version of the protograph extrinsic information transfer (PEXIT) algorithm and use it for deriving the threshold of the protograph codes in a single-input multiple-output (SIMO) system. We then calculate the decoding threshold and simulate the bit error rate (BER) of two protograph codes (accumulate-repeat-by-3-accumulate (AR3A) code and accumulate-repeat-by-4-jagged-accumulate (AR4JA) code), a regular (3, 6) LDPC code and two optimized irregular LDPC codes. The results reveal that the irregular codes achieve the best error performance in the low signal-to-noise-ratio (SNR) region and the AR3A code outperforms all other codes in the high-SNR region. Utilizing the theoretical analyses and the simulated results, we further discuss the effect of the diversity order on the performance of the protograph codes. Accordingly, the AR3A code stands out as a good candidate for wireless communication systems with multiple receive antennas.