面向多中继通信系统的可靠性编码与调制技术研究

With the rapid development of internet of things (IoT) and dense deployment of low-power mobile devices, the multi-relay-based wireless-communication techniques have drawn a great deal of attention from the academic community. Realizing reliable and efficient data transmission is a critical design objective of multi-relay systems. Although channel coding and spread-spectrum (SS) modulation can be utilized to significantly improve the quality of data transmission in wireless-communication scenarios, how to design excellent coding and SS modulation schemes for multi-relay systems is still a very challenging problem.. To address the aforementioned problem, this project plans to conduct an in-depth research on the design of protograph codes, chaos-based SS modulation, and their related techniques for multi-relay systems over multipath fading channels. To be specific, 1）we develop several efficient coded cooperative protocols as well as a Gray-mapped M-ary differential-chaos-shift-keying (DCSK) modulation, and derive their corresponding performance limits；2）we extend the theory of protograph extrinsic-information-transfer (PEXIT) function and analyze the asymptotic convergence and error performance of protograph codes；3）we optimize the structure of M-ary DCSK signal and design a family of multi-layer quasi-cyclic (QC) protograph codes to achieve fundamental-limit-approaching performance；4）we propose a new Turbo iterative detection algorithm and a dynamic-scheduling-mechanism-based joint belief-propagation (BP) decoding algorithm to boost the overall system performance. The expected results of this project can offer a more reliable and efficient data-transmission scheme for the next-generation wireless-communication applications.

随着物联网的快速发展和低功耗移动设备的密集部署，基于多中继的无线通信技术受到了学术界的广泛关注。实现可靠高效的数据传输是多中继系统的一个重要设计目标。虽然信道编码和扩频调制可显著改善无线通信的数据传输质量，但如何在多中继系统中设计优秀的编码与扩频调制方案仍是一个极具挑战性的问题。. 本项目拟在多径衰落信道中对多中继系统的原模图码、混沌扩频调制及其相关技术展开深入研究：1）开发高效的编码协作协议和基于格雷映射的M元差分混沌键控，并推导多中继协作系统的性能极限；2）完善原模图码的外信息转移函数理论，分析其渐近收敛与纠错性能；3）优化M元差分混沌键控的信号结构，设计低复杂度的分层准循环原模图码，获得靠近系统极限的性能；4）提出全新的Turbo迭代检测算法和基于动态调度机制的联合信度传播译码算法，以提升系统的整体性能。相关研究成果可为新一代无线通信应用提供一种更可靠更高效的数据传输方案。

随着物联网的快速发展，多中继协作通信技术得到了学术界的广泛关注。然而，新兴的物联网应用（如车联网、移动医疗）对通信质量提出了全新的要求，故如何提升多中继系统中数据传输的可靠性已成为一个亟待解决的关键问题。在现有的编码与调制技术中，低密度奇偶校验码与扩频调制在抗噪声和抗多径衰落方面具有天然的优势，已成为提高通信系统传输可靠性的重要手段。尤其是，原模图码和差分混沌扩频调制具有优异的纠错性能和很低的硬件复杂度，故与多中继应用的需求十分契合。. 为了提升物联网通信的服务质量，本项目对多中继系统中的可靠性编码和调制技术展开了深入研究。具体成果如下：1）在块衰落信道中开发了满分集分布式编码协作协议，并设计了逼近中断限的分层原模图码，获得了比传统协作协议和低密度奇偶校验码更优的纠错性能；2）在加性高斯白噪声信道中设计了逼近香农限的准循环低密度奇偶校验码及空间耦合原模图码，降低了传统码型的复杂度，并改善了收敛性能；3）在多径衰落信道中设计了高速率、高可靠的索引差分混沌扩频调制系统和LoRa扩频调制系统，并分析了其误比特率和复杂度。4）在多径衰落信道中提出了逼近容量限的原模图差分混沌编码调制方案及高效的BCJR差分检测算法，改善了传统差分混沌编码调制方案的性能。5）在多级单元闪存信道中提出了新颖的原模图编码调制方案及低复杂度检测算法，显著提高了系统的存储可靠性。. 在该项目的支持下，已发表学术论文54篇，其中SCI论文41篇，EI论文13篇，授权发明专利22件。在所发表的SCI论文中，包含IEEE汇刊/杂志论文25篇，IEEE短文10篇，ESI高被引论文2篇，亮点论文1篇。以第一完成人获得广东省自然科学二等奖1项，并获得国际会议最佳论文奖1项。. 相关研究成果不仅完善了原模图码和混沌扩频调制理论体系，而且为新一代无线通信系统提供了一种有竞争力的数据传输技术解决方案。