面向非空室内场景的分布式可见光通信信道表征研究

Visible light communications (VLC) is an emerging technology using visible lightwave as medium of wireless transmission. It can provide unique characteristics, including huge spectrum resource, no radio regulation and so on. As white LEDs are widely applied in various scenarios, this technology has earned unprecedented attention. However, at present, the indoor transmission characteristics of VLC are still unclear. Exist method can only analyze limited point sources within fully empty room. The related conclusions work with obvious limitation. This project based on exist research foundation of indoor VLC channel and actual style of LED sources array, will address the propagation characteristics of visible light signal from different distributed sources under the condition of typical room structure, conventional indoor furnishings and flexible receiver orientation. Specially, the modeling scheme and effective algorithm which can comprehensively consider indoor space, indoor surface reflection pattern will be proposed. Moreover, the reliability of results through simulation modeling will be verified theoretically by vast data from actual measurement. The extra attention will be focused on the change rule between channel transmission bandwidth and obstacle size among different receiver locations. Remarkable advancement in VLC channel characterization will be made by this project, which will provide substantial support of physical layer to the development of this technology.

可见光通信是以可见光波为信息载体实现无线信息传输的新兴技术，具备信号自身可见、光谱资源巨大，无频谱管制等一系列独特属性。随着白光LED被广泛应用于各类室内场所，此项技术获得空前的关注。然而，目前可见光通信室内传输特性仍不明晰。现有分析方法仅能在全空房间环境下，有限几个点光源的信道特性进行分析，所获结论尚有很大的局限性。本项目将依托已有可见光通信信道的研究基础，结合LED光源阵列的实际形态，研究在典型房间结构、常规室内陈设以及接收机灵活指向条件下，多组分布式光源所发可见光信号的传播特性，提出能够综合考虑室内空间、室内表面反射模式的建模方案及有效算法，进而借助大量实测数据对仿真建模结果的准确性进行系统性验证，重点关注非空室内条件下不同接收位置信道传输带宽的变化规律及其与障碍物尺寸的对应关系。本项目将在见光通信信道表征上取得显著进展，为此项技术的发展提供坚实的物理层依据。

综合实际场景及光源设定的室内可见光通信信道建模表征是提升此类技术实用性所不可或缺的基础性工作。 面向场景设定与光源分布等关键属性，本项目系统开展了基于确定性（环境表面分割建模法）建模方案，基于非确定性（蒙特卡洛光线跟踪）建模方案，以及基于积分球方案的室内可见光通信信道表征及方案改进研究。与此同时，重点研究了常见的发端光源阵列简化处理对所获的室内可见光通信信道特性（主要包括：信道冲激响应，光路径损耗，均方根时延扩展等）的潜在影响与变化规律。结合对商用光源的实测结果，突破了已有工作仅能表征朗伯类光源的天然局限性，完成了对对称非朗伯、非对称非朗伯等众多实际光源辐射模式的三维空间模拟表征，系统性量化比较了多类实际商用光源设定下，室内可见光通信在空间信道特性上的显著差异，为后续可见光系统性能提升与设计优化开辟了一个崭新的自由度。在此基础上，针对室内可见光通信系统兼具无线通信与通用照明的双重功能，构建了完备的能涵盖室内多重反射对接收平面照度贡献的数学模型与仿真体系，克服了已有工作仅考虑直射路径贡献的局限性，充分评估了此类系统通过反射路径照明的显著占比。此外，面向分布式光源，量化研究了光学透镜组对多输入多输出可见光通信所引入的潜在信道增益并为进一步的性能提升指明了方向。