【作者】 李涛；

【导师】 张在琛；

【作者基本信息】 东南大学 ， 信息与通信工程， 2016， 硕士

【摘要】 随着技术的进步以及各种终端设备的普及,人们对无线通信数据传输速率以及服务质量提出了更高的要求。面对更高速、更可靠的数据传输要求和紧缺的无线频谱资源,处于免费频段、拥有着巨大潜在通信容量同时可用于照明的可见光波段的可见光通信引起了国内外学术界和工业界的极大关注。本文主要对利用可见光频谱进行数据传输的可见光通信技术进行研究,并设计和实现了一个基于RGB LED光源的高速可见光通信系统。首先,本文针对可见光通信系统的物理层技术进行调研,并提出了一种利用ACO-OFDM系统时域信号的反周期对称特性对系统中的裁剪位置信号进行恢复的优化算法。首先从可见光通信系统的系统模型入手,分析ACO-OFDM系统中信号的相关特性,并根据时域信号的反周期对称性推导出信号恢复优化算法,得到了优化的接收机模型,经过理论分析与仿真验证得出该优化算法可有效提高接收机的性能。然后,本文对可见光通信系统收发端的驱动电路进行了设计和硬件实现。在发送端,通过详细介绍使用的RGBA LED的工作特性,分析使用场效应管驱动LED的电路原理,完成了对LED驱动电路的参数设计。在接收端,基于所使用的PD的性能参数,分析了驱动PD的跨阻放大和电压放大两级放大器的电路原理,完成了对PD驱动电路的参数设计。接着,本文研究可见光通信系统的数字基带部分的设计与实现。首先针对DCO-OFDM系统模型,在给出的系统整体框图基础上,对包括基本参数、物理层数据帧结构和基带实现结构三部分的系统基带方案进行了设计。然后对基带系统中发射端和接收端的FPGA实现进行了详细介绍,重点阐述了收发端FPGA实现中重要模块的硬件设计和实现细节。最后,本文对所实现的基于DCO-OFDM的高速可见光通信系统进行了测试分析。测试内容包括信道频率响应、时域信号波形、信号频谱、传输速率和误比特率等。测试结果表明,在不加卷积编码时系统应用层的平均速率可达508Mbps且误比特率低于10-4量级,当加1/2卷积编码且传输距离为3m时系统能够实现高清视频实时可靠的传输,成功实现了预期的系统指标。更多还原

【Abstract】 With the advancement of wireless communication technology and the popularization of various terminal equipments, the data transmission rate and the service quality of wireless communication are put forward higher requirements. In the face of higher speed and more reliable data transmission requirements as well as scarce radio spectrum resources, visible light communication (VLC), which utilizes free visible light band and holds a huge potential for communication capacity, has attracted great attention from domestic and international academic and industrial area. This thesis will study VLC technology which uses visible light to transfer data, and focus on the design and hardware realization of a high-speed VLC system based on RGB light emitting diode (LED) as light sources.Firstly, this paper investigates the physical layer technology of VLC system and proposes a novel optimization algorithm by making use of the anti-periodic property of asymmetrically clipped optical orthogonal frequency division multiplexing (ACO-OFDM) time domain signal to recover the clipping signal at the ACO-OFDM receiver. With the beginning of illustrating the VLC system model, we analyze the characteristics of signal in ACO-OFDM system and provide theoretical analysis of the proposed optimization algorithm. And then the optimal receiver model is deduced and the effectiveness of the proposed optimization algorithm is verified via simulation.Secondly, the circuit of VLC transceiver end driver is designed and implemented. At the transmitter, by introducing the operating characteristics of RGBA LED and analyzing the circuit theory of using field effect transistor (FET) to drive LED, this paper finishes the key parameters design of LED driver circuit. At the receiver, after studying the performance parameters of photodiode (PD) and analyzing the principle of PD two-stage amplifier driving circuit, including trans-impedance amplifier (TIA) and voltage amplifier, the detailed key parameters of PD driver circuit are provided.Thirdly, this thesis studies the hardware design and implementation of the VLC system digital baseband. Based on the DC-biased optical orthogonal frequency division multiplexing (DCO-OFDM) system model and the overall system block diagram, the system baseband scheme, including basic parameters, physical layer data frame structure and baseband implementation structure and so on, are designed. And then this paper demonstrates the method of the field programmable gate array (FPGA) hardware realization of the designed VLC system digital baseband, especially the implementation details of the transceiver’s key modules.Finally, detailed analysis and tests of the DCO-OFDM VLC system are performed, including channel frequency response, time-domain waveform signal, signal spectrum, transfer rate and bit error rate (BER). The test results indicate that without convolution encoder, the average rate of application layer is about 508Mbps and BER is less than 10-4, and when adding 1/2 convolution encoder and setting 3m transmission distance, the system can achieve high-definition video in real-time and reliable transmission, the high-speed VLC system constructed in this paper successfully realize the system requirements.更多还原