面向下一代无线通信系统的多进制原模图LDPC码的优化设计与性能分析

With continued development of modern information and communication technologies, large attention is focused on further enhancing the quality of data transmission, which promotes the research on the next-generation wireless communication systems. Error-correction codes (ECCs) can be utilized to significantly improve the error performance of wireless communication systems. As a type of excellent ECCs, the protograph (LDPC) codes not only can inherit the advantages of conventional LDPC codes, but also can realize linear encoding and decoding.. Based on the previously fundamental research on the binary protograph-based (PB) codes, we plan to conduct an investigation on design of the encoding and decoding algorithms of non-binary PB (NBPB) codes for wireless communication systems, as well as their combination with the high-order modulations. Through the systematic study of NBPB codes over fading channels, 1) we develop new finite-length and infinite-length NB protograph extrinsic information transfer (PEXIT) algorithms so as to analyze their convergence performance and derive their asymptotic bit-error-rate (BER) and word-error-rate (WER) expressions; 2) we further propose a design scheme for the NBPB codes in order to achieve the fundamental-limit-approaching error performance according to the PEXIT analytical results; 3) we finally analyze the performance of high-order modulated NBPB codes by exploiting the finite-length PEXIT algorithm as well as optimize their corresponding decoding tunnels, and hence provide a very good alternative ECC for the next-generation wireless communication systems.

随着现代信息通信技术的不断发展，如何进一步提高移动数据传输质量受到了广泛关注，这推动着下一代无线通信系统的研究。信道编码能够显著地改善无线通信系统的纠错性能。作为一种优越的信道编码，原模图LDPC码不仅继承了传统LDPC码的优点，而且能够实现线性编译码。. 本课题在已有二进制原模图码的研究基础上，拟将探讨多进制原模图码在无线通信系统中的编译码优化设计算法及其与高阶调制的结合。通过在衰落信道下系统研究多进制原模图码，1) 提出基于多进制原模图的有限长及无限长EXIT算法，分析该码型的收敛性能，推导其渐近误比特率与误字率表达式；2) 根据原模图EXIT分析结果，提出多进制原模图码的优化设计方案，使其达到靠近物理极限的纠错性能；3) 采用有限长原模图EXIT算法分析基于高阶调制的多进制原模图码的性能，并优化其译码通道，从而为下一代无线通信系统提供一种优秀的备选码型。

在无线通信场景下，低密度奇偶校验码能够获得逼近信道容量的性能，故在近二十年受到了广泛的关注。作为一类新颖的结构化低密度奇偶校验码，原模图码不仅拥有优越的纠错性能，而且也易于实现线性编译码。众所周知，低复杂度、高可靠性的数据传输是新一代无线通信系统的重要设计目标之一。因此，原模图码很有潜力成为新一代无线通信系统一种可行的数据传输解决方案。. 为了提升新一代无线通信系统的性能，本项目对原模图码的优化设计和性能分析展开了深入研究。具体成果如下：1）基于快衰落信道提出了原模图外信息转移函数算法及逼近容量限的原模图码构造方案，获得了比传统原模图码和低密度奇偶校验码更优异的纠错性能。2）基于中继块衰落信道发展了原模图外信息转移函数算法，分析了系统的中断限，并构造出了一类兼备线性最小距离和逼近中断限的码率兼容根原模图码。3）基于加性高斯白噪声信道设计了一类新颖的截断型空间耦合原模图码，不仅弥补了传统截断型空间耦合码的码率损失，且获得了更优的纠错性能。4）基于二维磁记录信道设计了一类逼近容量限的码率兼容原模图码，并完善了其性能分析理论。5）基于多径衰落信道提出了一种增强型的差分混沌键控原模图编码调制方案，并分析了系统的容量与纠错性能。. 在该项目的支持下，本课题组已发表学术论文24篇，其中SCI期刊论文17篇，EI会议论文6篇。在所发表的SCI期刊论文中，包含IEEE期刊论文16篇，IEEE Trans./Mag.论文8篇。申请发明专利8项，授权实用新型专利2项。. 本项目的相关研究成果不仅丰富了原模图码的理论体系，而且为新一代无线通信系统提供了一种重要的信道编码方案。