移动场景下的高速散射紫外光通信无线传输理论与系统

The ultraviolet communication (UVC) uses UV lights of wavelength in the solar blind region (200-280nm), and transports signals through non-line-of-sight (NLOS) channels due to the scatter effect of the atmosphere. Its advantages mainly include non-alignment transmitter-receiver, great terrain-adaptability, high confidentiality, anti-interference and flexibility in networking. It is also called the “optical radio station” and has wide application prospects.. The present UVC systems usually work at a low transport rate with poor reliability, and the transmitter and the receiver are stationary. This project intends to study two key problems in mobile scenarios, i.e., the propagation reliability of space- and time-variant UV scatter channels and the design of UVC systems with high transport rate and reliability. Accordingly, this project will put forward a propagation model for space- and time-variant multiple-input multiple-output (MIMO) multiple-scatter channels, and analyze the channel characteristics and capacity affected by the configuration parameters and the mobility of the transmitter and the receiver. Then, a MIMO UVC system framework for mobile platforms will be proposed. For the first time, we innovatively design a zoom scattering UV optical antenna with large field of view for mobile applications, and present for UV intensity modulation a parallel concatenated low-density parity check code (LDPC) scheme and a joint iterative decoding scheme of LDPC and MIMO. An adaptive hybrid space-time coding scheme is also adopted. Therefore, the transport rate of the proposed UVC system will increase by one order of magnitude from a few hundred kbps to several Mbps.

紫外光通信（UVC）采用日盲区紫外波段的光波，通过大气的散射作用进行非视距（NLOS）传输，其收发机无须对准、地形适应性好、保密性强、抗干扰、组网灵活，被称为“光电台”，具有广阔的应用前景。. 目前的UVC系统通信速率低、可靠性差，并且收发机位置固定。本项目拟围绕移动场景下空变时变UV散射信道传输的可靠性和高速可靠的UVC系统设计这两个关键问题展开研究。为此，本项目将建立空变时变多输入多输出（MIMO）多散射信道传输模型，分析收发机参数和移动性对信道特性和容量的影响，然后提出适于移动平台的 MIMO UVC系统架构，其中首次创新性地提出适合移动应用的变焦距、大视场、散射型UV光学天线结构及设计方法，首次提出适合UV强度调制的并行级联低密度奇偶校验码（LDPC）及其与MIMO联合迭代的译码方案，并引入自适应混合空时编码方案，从而最终实现通信速率从百kbps到Mbps的数量级跨越。

紫外光通信（UVC）采用日盲区紫外波段的光波，通过大气的散射作用进行非视距（NLOS）传输。UVC地形适应性好、保密性强、抗干扰、组网灵活,因而具有广阔的应用前景。但目前UVC系统存在通信速率低、可靠性差，收发机固定等问题，限制了UVC的灵活有效应用。.本课题主要研究了适用于移动的湍流多输入多输出（MIMO）UVC框架、并行级联的低密度奇偶校验码（LDPC）编码、宽视场高增益变焦光学天线、高速可靠的UVC系统等方面。所得重要结果和关键数据具体为：.1）考虑信道空间相关性，创新性地提出了非共面的MIMO UVC方案。结合节点移动性，首次提出了一种Mesh网络的移动自组网框架，并设计了一种适用UV MIMO的改进的SD检测算法。显著地降低了信号检测复杂度，误码率（BER）小于1E-3。为用户在信号覆盖范围内的高速移动通信提供了理论依据。.2）首次设计实现了适于移动接收的变焦距大视场高增益UV光学天线。实验测试的变焦光学天线关键指标如下：焦距分别为16.5mm，33mm，41mm，对应视场角分别为72°、54°、38°;光学增益最高可达20.7；光学效率达92%以上，变倍比最高可达3.2。.3）首次提出了适用于UVC的并行级联LDPC与MIMO联合迭代的译码方案。根据紫外信道特性，针对性地设计了的新型启发式LDPC编码算法，解决了高速NLOS散射 UVC容易产生码间干扰（ISI）的问题。并与传统LDPC性能对比进行了优化，兆比特速率情况下得到256码长的最佳方案，最高编码增益可达20db。.4）搭建了远距离室外UVC通信硬件系统平台，最高传输速率2Mbps时，通信距离可达300m，未编码BER为1.23E-2，LDPC编码后的BER为6.32E-5。.该高速通信UVC系统具有功率低、信噪比高、抗干扰、高保密、环境适应力强等优点。主要可用于海上船舶、地面车辆以及空中机队等军事领域，对国防建设起到推动作用。.课题组完成了2M、200m、1E-4的指标要求，实现了远距离高速可靠UVC系统。此外，共发表研究成果27项，其中SCI论文9篇（二区7篇，三区1篇，四区1篇），北大中文核心期刊1篇，EI论文6篇，专利11项。共培养博士3人，硕士7人。超额完成课题任务要求。