基于定向波束空分复用的三维无线自组织网络基础理论研究

The three-dimensional (3D) wireless ad hoc networks that are usually constructed with buildings or terrains have important application spectrum for communications in cities and battle fields. To make full use of resources in spatial and polarization domains, this proposal conducts research in the new direction of 3D networks that utilize orthogonal-polarized beamforming and spatial multiplexing based on full-dimensional multiple-input-multiple-output (FD-MIMO). The characteristics of wave beams are the critical factors that determine the network performance and capacity. However, spatial channel propagations will introduce random variations of the key parameters of wave beams, such as beam width and polarization-diversity gain. Moreover, the subchannel allocation and link establishment in 3D space is more complex and the deafness problem is more challenging. This proposal starts with the characterization of channel and 3D beamforming. First, by field measurements of multipath propagations jointly in polarization, temporal, and spatial domains, the channel statistical models of the 3D ad hoc networks are built. Then, the impact of spatial channel propagations on 3D beamforming and polarization diversity is investigated in-depth. Finally, the network capacity is analyzed and the directional MAC protocols are designed based on the beamforming characteristics. The cross-layer design methodology in this proposal avoids assuming ideal, fixed beamforming parameters as in the traditional network studies, and therefore the network analysis is more reasonable. The proposed 3D channel models can be used in evaluations for not only FD-MIMO but also other two-dimensional antenna array technologies, and therefore help to improve the capacity of 3D networks.

依靠建筑或地形构成三维（3D）立体无线自组织（Ad Hoc）网络对城市通信和野外作战具有重要的应用前景。为充分利用空域和极化域资源，本项目研究基于全维度-多输入多输出（FD-MIMO）3D正交极化波束的空分复用网络这一新方向。波束特性是决定网络性能和容量的基本要素，但是空间信道传播导致波束宽度、极化分集增益等关键参数随机变化，尚缺乏研究。此外，3D空间多子信道分配和链路建立更加复杂，聋节点问题更加突出。本项目以3D信道传播和波束成形为出发点，首先通过极化-时-空域联合测量，建立3D Ad Hoc网络的信道统计模型；然后深入研究信道对3D波束成形与极化分集的影响机理；进而以波束特性为依据，分析网络容量与设计定向MAC协议。该跨层设计方法避免了传统研究中理想、单一的波束参数假设，网络分析更加合理。所提出的3D信道模型，可用于FD-MIMO及其他二维天线阵列技术的研究，提高3D网络通信容量。

该项目面向三维无线自组织网络的高效率空分复用技术开展基础理论研究，全面系统地研究了三维拓扑网络典型场景下的极化-空-时无线信道测量方法、信道建模、基于信道传播特性的网络性能分析和网络跨层设计。（1）提出了多种创新的高分辨率、空-时域联合的无线信道多径传播参数估计算法，并自主研制了多维域信道测量系统，通过理论证明和实际系统测试，验证了所提出算法的有效性；该工作解决了三维空间密集多径散射环境下信道传播测量的难题。（2）针对地面和空-地三维拓扑网络的典型场景，进行了大量信道传播参数（例如大尺度衰落、多径波达/波发角、空间角度功率谱等）的测量，获得了宝贵的实测数据，建立了场景化信道数据库；并进而构建了多种场景下的信道几何散射模型，解决了现有模型缺乏和准确度低的问题。（3）基于物理层信道模型，进行了网络编码、多址接入、路由规划、节点定位等算法和协议的跨层设计，有效提高了三维拓扑网络的速率、可靠性和能量利用率。该项目的信道测量数据与模型向国际电信标准组织3GPP提交了信道模型提案并被列入国际标准，为接入网空口标准的完成提供了基础数据和模型，为移动通信系统提供了性能分析、方案评估对比和系统仿真验证的理论依据。此外，该项目提出无线信道模型和多址接入技术被多家公司和研究所应用于水厂分布式控制系统、博物馆环境监测网络、无人机空中基站的设计和部署。本项目的工作为进一步完善三维信道传播模型与理论、探索实际传播环境对天线阵列、波束成形、网络协议影响和制约的机理、提升三维拓扑网络性能的提供了基本理论与方法。