Optimization of Protograph LDPC Codes via Surrogate Channel for Unequal Power Allocation
Optimization of Protograph LDPC Codes via Surrogate Channel for Unequal Power Allocation
复制标题
通过代理信道优化原型 LDPC 码以实现不等功率分配
DOI：
10.1109/tcomm.2023.3237845
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发表时间：
2023-03-01
影响因子：
8.3
通讯作者：
Zhou, Lin
中科院分区：
文献类型：
--
作者：
Chen, Qiwang;He, Yu-Cheng;Zhou, Lin
本文调查了优化现有的Protograph低密度平价检查（PLDPC）代码的可能性，并在二元调制下对AWGN和Rayleigh通道上的最佳PLDPC代码设计，并以不均匀的功率分配（UPA）的不均匀来源设计。虽然二进制UPA调制获得了功率增益，但在传输过程中系统的代码字上的编码位也会导致不平等的错误保护。对于不规则的代码，可以通过优化可变节点（VNS）的分类来最好地保护信息位。这些VN代表了原始的编码位，允许共同利用程度不规则性和功率分化。提出了一种基于UPA的原始外部信息传输（UPA-PEXIT）分析的算法，该算法是用替代通道的概念提出的，该概念避免了UPA的通道不对称问题。以RJA代码为例，可以表明，当源熵较小时，分类优化确实改善了解码阈值。为了设计最佳代码，提出了一种基于UPA的差异进化（UPA-DE）算法，并与UPA-PEXIT分析一起提出。为三个典型的非均匀源分布提供了一组优化的代码，并通过模拟错误率性能进行了与RJA和NND代码进行了比较。
This paper investigates the possibilities of optimizing existing protograph low-density parity-check (PLDPC) codes and designing optimal PLDPC codes on both AWGN and Rayleigh channels under binary modulation with unequal power allocation (UPA) for nonuniform sources. While the binary UPA modulation achieves a power gain, it also results in unequal error protection on the coded bits in systematic codewords during transmission. For irregular codes, it is possible to best protect the information bits by optimizing the classification of variable nodes (VNs). Those VNs represent the coded bits in protograph that allows exploiting jointly the degree irregularity and the power differentiation. An algorithm for UPA-based protograph extrinsic information transfer (UPA-PEXIT) analysis on the Rayleigh channel is proposed with the concept of surrogate channel which circumvents the channel asymmetry problem with UPA. With the RJA code as example, it is shown that classification optimization does improve the decoding threshold when the source entropy is small. To design optimal codes, a UPA-based differential evolution (UPA-DE) algorithm is proposed in conjunction with the UPA-PEXIT analysis. A family of optimized codes are illustrated for three typical nonuniform source distributions and compared with the RJA and NND codes by simulations in error rate performance.