网络编码在MIMO多向中继信道中的优化设计与性能分析

Physical-layer network coding (PNC) has been intensively investigated in the past several years. The simplest model for PNC is the two-way relay channel (TWRC), in which two users exchange information via the help of a single relay. The conventional protocol for TWRC requires four phases to complete one round of information exchange, while PNC reduces the required number of phases to two by allowing two users to transmit/receive signals simultaneously, so as to double the network throughput. A multiway relay channel (MWRC), as a natural generalization of TWRC, allows an arbitrary number of users to exchange information via a relay. However, as the relay simultaneously serves a large number of users in a MWRC, the network throughput is usually bottlenecked by the relay's capability of receiving and transmitting signals. In the proposed research, we intend to eliminate the above bottleneck by introducing multiple-input multiple-output (MIMO) into MWRCs, which enables the relay and users to transmit and receive multiple signal streams simultaneously. The goal of the proposed research is to investigate the joint design of the cutting-edge technologies (including MIMO, PNC, and advanced error-correction coding, etc) for MWRCs, and to push them towards the fundamental performance limit of the network. This is a very challenging task, given the fact that so far we have limited knowledge on the capacity of wireless networks, even for the simplest three-node TWRC model. To fulfill this goal, it is of critial importance to carefully manage interference in a MIMO MWRC: on one hand, signal streams from different users cause multiuser interference in the relay network; on the other hand, each user transmits multiple spatial signal streams, which gives rise to inter-stream interference. The proposed research aims to design and analyze various advanced interference alignment/suppression/cancellation techniques, including but not limited to, lattice coding, linear precoding, lattice precoding, and successive interference cancellation, etc. We will investigate the joint design of network coding and the interference management techniques for MIMO MWRCs, and propose solutions to approach the fundamental performance limit of the relay networks. If successful, this research will bring forward a solid step in the theory and priacice of PNC for MIMO relay channels, and can provide key technologies for the next generation wireless communication networks.

本项目针对国家重大专项"新一代宽带无线移动通信网"中对新一代移动通信网络关键技术研发、标准化和产业化的中长期规划和要求，研究网络编码和MIMO技术在无线中继网络中的应用，分析MIMO多向中继信道中的干扰形成机制，设计网格编码、线性预编码、网格预编码、连续干扰消除等先进的抗干扰技术，提出结合MIMO-网络编码-抗干扰技术的联合设计方案，并优化中继网络参数使得系统性能逼近理论最佳值。本项目的关键难点在于如何在多向中继网络中联合设计网络编码和MIMO技术，有效地控制和消除多用户干扰和流间干扰，从而达到或靠近网络的性能极限。本项目将系统地研究这些关键技术，从信息论的角度分析与推导无线中继网络的信道容量极限，填补"MIMO多向中继网络的信道容量"这一重要理论研究领域的空白。同时，本项目的研究成果将大幅提升无线网络的频谱效率和数据吞吐量，进而为新一代移动通信网络的设计与标准化提供解决方案。

本项目针对国家重大专项“新一代宽带无线移动通信网”中对新一代移动通信网络关键技术研发、标准化和产业化的中长期规划和要求, 研究网络编码和MIMO技术在无线中继网络中的应用，深入理解MIMO多向中继信道中干扰的形成机制，设计和分析各种先进的干扰消除技术，提出结合MIMO-网络编码-干扰消除技术的联合设计方案，并优化系统参数使得系统性能逼近理论最佳值，从而大幅提升网络频谱效率和数据吞吐量，并以此为基础为新一代移动通信网络的设计与标准化提供了解决方案。主要包括：分析和推导各类MIMO多向中继信道的自由度；分析各类MIMO多向中继信道的信道容量；分析多向中继系统的信道编码与信道估计；分析MIMO多向中继网络的安全性。.基于此，本项目建立了相对成熟的MIMO多向中继网络数学模型，形成和完善了描述系统自由度容量的理论体系；形成和完善了MIMO 多向中继网络的信道容量的描述，推导和建立了信道容量上下界的数学表述； 提出了先进的融合网络编码与各类抗干扰技术的中继通信系统设计方案，完成了相关方案的软件仿真；提出了网络编码-抗干扰-信道编码调制联合设计的解决方案，分析了MIMO多向中继网络中的协作通信增益； 提出了在MIMO 多向中继网络中进行安全通信的系统设计解决方案，并对该方案进行理论分析和性能仿真；发表IEEE国际期刊文章18篇，国际会议文章17篇，其中SCI检索文章17篇，EI 检索文章16篇，参加国际学术会议13人次； 申请国家发明专利2项。培养博士研究生5人、硕士研究生4名。项目成果获得中国电子学会科学技术奖二等奖，获奖项目名称为《高效多向中继网络传输理论与关键技术》。