可见光通信系统的研究与实现

发布时间：2018-06-03 14:20

本文选题：可见光通信 + 均衡　；参考：《华侨大学》2017年硕士论文

【摘要】：可见光通信(Visible Light Communication,VLC)是一种基于LED的新兴无线通信技术。它利用LED的高速调制特性,先将信号调制到光源上,通过灯光将信息传送出去,再被接收端解调恢复,达到光通信的目的。VLC可同时兼顾照明和通信功能,具有成本低、无辐射、不占用无线频谱等优点。目前国内外学者对于可见光通信技术的研究,大多专注于通信速率的提高,但同时也存在系统稳定性差、成本过高、不利于普及与推广等弊端。针对这一现象,本课题研究低速率、低复杂度、高稳定性的可见光通信技术。首先,论文介绍了可见光通信的研究背景,总结了国内外关于可见光通信的研究现状,针对目前研究的不足之处,阐述了本课题的研究意义。其次,分析了可见光通信系统构成。参照系统模型,描述了LED光源特性和光电探测器(Photo-Detector,PD)特性,总结了可见光信道特点,并将其建模为高莱斯因子、低多普勒效应影响的莱斯衰落信道。再次,针对可见光信道中的衰落现象,研究了均衡技术。通过总结现有均衡算法,提出了一种改进的变步长LMS算法。该算法以误差函数作为步长调整的基础,并利用初等函数分段近似替代误差函数,来降低计算复杂度。仿真结果表明,改进算法能够在可见光信道下实现较低的稳态误差和较快的收敛速度,因而更适用于可见光通信系统。最后,在上述工作基础上,给出了可见光通信系统设计方案,并搭建了一套演示系统。该系统发射机部分包括LED驱动电路和数字基带电路,数字基带部分包含串口转换、数据封帧、扰码、信道编码、交织等模块;接收机部分包括两级放大电路及定时同步、解交织、解码、解扰、解帧等模块。基于该演示系统,我们利用LED发出的绿光实现了点对点通信功能,验证了设计方案的可行性,且系统简单可靠、成本较低,达到了设计要求。
[Abstract]:Visible Light Communication (VLC) is a new wireless communication technology based on LED. It uses the high speed modulation characteristic of LED, first modulates the signal to the light source, transmits the information through the light, and then demodulates and recovers the signal at the receiving end. The purpose of the optical communication is to combine the lighting and communication functions, which has the advantages of low cost and no radiation. Does not occupy the wireless spectrum and other advantages. At present, most scholars at home and abroad focus on the improvement of communication rate, but at the same time, there are some disadvantages such as poor system stability and high cost, which is not conducive to popularization and popularization. In view of this phenomenon, we study the low-rate, low-complexity, high-stability visible light communication technology. Firstly, the paper introduces the research background of visible light communication, summarizes the current research situation of visible light communication at home and abroad, and expounds the significance of this research in view of the shortcomings of the current research. Secondly, the structure of visible light communication system is analyzed. Referring to the system model, the characteristics of LED light source and photodetector are described, and the characteristics of visible light channel are summarized, and it is modeled as a Rice fading channel with high Les factor and low Doppler effect. Thirdly, the equalization technique is studied for the fading phenomenon in the visible light channel. By summarizing the existing equalization algorithms, an improved variable step size LMS algorithm is proposed. The algorithm uses the error function as the basis of step size adjustment and uses the elementary function to approximate the error function in order to reduce the computational complexity. Simulation results show that the improved algorithm can achieve lower steady-state error and faster convergence speed in visible light channels, so it is more suitable for visible light communication systems. Finally, on the basis of the above work, the design scheme of visible light communication system is given, and a set of demonstration system is built. The transmitter part of the system includes a LED driving circuit and a digital baseband circuit. The digital baseband part includes a serial port conversion module, a data packet frame module, a scrambling code module, a channel coding module, an interleaving module, etc.; the receiver part includes a two-stage amplifier circuit and a timing synchronization module. Deinterleaving, decoding, descrambling, deframing and other modules. Based on the demonstration system, we use the green light from LED to realize the point-to-point communication function, verify the feasibility of the design scheme, and the system is simple and reliable, the cost is low, and meet the design requirements.
【学位授予单位】：华侨大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN929.1

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