融合能量收集的室外可见光通信理论与方法研究

The outdoor visible light communication between solar LED traffic lights has the advantages of low carbon, saving energy, and environmental protection. This means of communication collects the camera monitoring information at the crossing via visible light transmission, therefore the cost of infrastructure for wire transmission is reduced. However, the progress of outdoor visible light communication is impeded by sunlight and atmospheric turbulence. In order to solve these problems, this project will investigate the fundamental theories and critical techniques for outdoor visible light communication with green energy harvesting, mainly including: 1) by optimizing the parameter of receiving circuit, analyze the impacts of sunlight irradiance and receiver size on signal-to-noise ratio and energy conversion, and illustrate the mechanism of consideration of communication and energy harvesting as a whole; 2) according to the inhomogeneous of the distribution of air refractive index, analyze the impacts of parameters such as temperature, relative humidity and air quality index on refractive index and the waveform distortion, and consider the physical properties of LED light adequately to establish the mathematical model of the LED light propagation in atmospheric channel; 3) by utilizing the property of bi-directional transmission of outdoor visible light communication, analyze the coherence characteristics of atmospheric channel to investigate the mechanism of adaptive resource allocation, and by using the technique of interference mitigation, break the constraint of LED’s field of view and establish the mechanism of information collection via visible light. The results of this project will provide theoretical foundation and technical support for high capacity outdoor visible light communication with energy harvesting.

太阳能LED交通灯之间的室外可见光通信具有低碳、节能、环保等优势。该通信方式将路口监控信息通过可见光传输进行汇总，减少有线传输带来的建设成本。但是太阳光和大气湍流制约着室外可见光通信的发展。本课题将针对上述问题研究融合绿色能量收集的室外可见光通信的基础理论和关键技术，主要包括：1）通过优化接收电路参数，分析太阳光强度和接收器尺寸对于信噪比和能量转化的影响，阐明统筹通信和能量收集的机理；2）针对空气折射率分布不均匀的特点，分析温度、相对湿度、空气质量指数等参数对折射率的影响和导致的波形畸变，并充分考虑LED光物理性质，构建LED光大气信道传输数学模型；3）利用室外可见光通信双向传输的特点，分析大气信道的相干特性，研究资源的自适应配置机制，并通过干扰抑制技术，突破LED光场视角限制，建立信息的可见光汇总机制。研究成果将为融合能量收集的大容量室外可见光通信提供理论基础和技术支撑。

本项目旨在研究融合能量收集的室外可见光通信的基础理论和关键技术。室外可见光通信系统主要受到太阳背景光的影响，会出现系统传输带宽降低、接收信号信噪比下降、误码率性能恶化等现象。与此同时，太阳背景光又是良好的能量来源。充足的太阳背景光可以为接收端提供能量，减少室外可见光通信系统额外的能量消耗。因此，室外可见光通信系统可以将通信和能量收集融合在一起，以发光二极管为光源，以太阳能电池板为接收器。接收到的信号由交流和直流两部分组成，交流部分用于通信，直流部分用于能量收集以给通信系统供电。本项目研究了室外可见光通信系统的性能，主要包括：通过对比室内和室外可见光通信系统的频率响应曲线，研究了室外信道对于可见光通信系统传输能力的影响；通过传输实验，研究了室外可见光通信系统的误码率性能；根据不同子载波的信噪比特性，研究了基于自适应调制的室外可见光通信系统的传输能力；通过实验，研究了太阳能电池板能量收集能力。另外，本项目还研究了可提升室外可见光通信系统传输容量的非正交多址技术，主要包括：通过优化叠加星座图，改善两用户非正交多址可见光通信系统误码率性能的方案；通过采用遍历比较法，提升高阶调制方式下非正交多址可见光通信系统误码率性能的方案。