可见光通信高速移相关联空时编码技术研究
发布时间：2018-11-23 15:18
【摘要】：可见光通信(Visible Light Communication,VLC)将照明和通信有机结合,利用可见光新频谱资源,依托广泛覆盖的照明灯具,为缓解无线通信的“频谱紧张”、“深度覆盖”和“绿色节能”等问题提供了新手段。本文针对可见光通信的高速传输问题,重点研究了移相关联空时编码技术,主要研究内容和成果总结如下:1.测量和分析商用照明LED(Light Emitting Diodes)的直流传输特性和交流传输特性。测量了LED的电压—电流、电流—光通量两种转化特性,采用多项式对LED的非线性进行了拟合建模,分析了非线性对高阶调制信号的影响。测量了三种颜色LED灯芯的幅频响应曲线,给出了时域和频域预均衡方法。2.针对单LED传输速率受限的问题,提出了多LED移相空时叠加传输方法,实现了传输速率的成倍提升。采用LED内部的多个灯芯实现并行传输,通过相对移相后,利用光在空间的自然线性叠加特性,构造出了一种等效的多输入、单输出传输系统。设计了分块移相空时码,给出了其快速检测算法。理论分析表明其频谱利用率与LED灯芯的数目成正比,且在衰落信道条件下可以达到满分集。为进一步提升频谱利用率,在分块移相空时码的基础上,构建了块级联移相空时码,设计了防止差错传播的预编码方法,分析了其误比特性能。相比于单路传输,块级联移相空时码可以将频谱利用率提升至N倍(N为LED灯芯个数),达到全速率。与可见光通信中常用的OFDM(Orthogonal Frequency Division Multiplexing)的仿真对比表明,多LED移相空时码可以达到更高的传输速率,且抗LED非线性性能更好。3.为了提升系统在低通频选信道下传输性能,将唯一可分解星座对(Uniquely Factorable Constellation Pair,UFCP)技术与可见光通信相结合,构造了星座关联的VLC OFDM技术和星座关联的多LED移相空时码。星座关联的VLC OFDM技术将不同子载波上的符号之间相互关联,在接收端联合解调,从而提升了系统的抗频率选择特性。在此基础上,给出了基于星座关联的VLC OFDM的最大似然检测方法,分析了VLC OFDM在采用星座关联技术后所获得的平均欧氏距离增益。通过将UFCP技术与块级联移相空时码相结合,提出了一种星座关联的块级联移相空时码,其实质在于将块级联移相空时码中不同支路的符号关联起来,联合解调以获得增益。数值仿真结果表明,引入星座关联的方法可以获得0.8-1.5 dB的信噪比增益。4.针对室内可见光通信的典型应用,设计实现了两种可见光通信基带传输系统。一是面向中低速可见光通信应用需求,设计并实现了50 Mbit/s可见光通信芯片基带原型系统,给出了可见光基带芯片的系统结构、功能指标,并详细介绍了FPGA上各模块的实现流程。二是面向高速可见光通信应用需求,利用本文提出的星座关联块级联移相空时编码,采用RGB LED的三个灯芯实现了三路信号的叠加传输,设计并实现800 Mbit/s离线处理系统。
[Abstract]:Visible light communication (Visible Light Communication,VLC) combines lighting and communication organically, using the new spectrum resources of visible light, relying on the widely covered lighting lamps, in order to alleviate the "spectrum tension" of wireless communication. Such issues as "deep coverage" and "green energy conservation" provide new means. Aiming at the problem of high speed transmission of visible light communication, this paper focuses on the phase shift associated space-time coding technology. The main research contents and results are summarized as follows: 1. The DC and AC transmission characteristics of commercial lighting LED (Light Emitting Diodes) are measured and analyzed. The voltage-current and current-luminous flux conversion characteristics of LED are measured. The nonlinear characteristics of LED are modeled by polynomial, and the influence of nonlinearity on high-order modulation signals is analyzed. The amplitude-frequency response curves of three color LED cores are measured, and the time-domain and frequency-domain preequalization methods are given. 2. In order to solve the problem of limited transmission rate of single LED, a method of superposition transmission with multiple LED phase shift is proposed, which can increase the transmission rate exponentially. A multi-input and single-output transmission system is constructed by using the natural linear superposition of light in space after relative phase shift. The block phase shift space-time code is designed and its fast detection algorithm is given. Theoretical analysis shows that the spectrum efficiency is proportional to the number of LED cores and can reach full diversity in fading channels. In order to further improve the spectral efficiency, a block concatenated phase-shifted space-time code is constructed on the basis of block phase-shifted space-time code. A precoding method to prevent error propagation is designed, and its bit error performance is analyzed. Compared with single-channel transmission, block concatenated phase-shifted space-time codes can increase the spectral efficiency to N times (N is the number of LED wicks) and achieve full rate. Compared with OFDM (Orthogonal Frequency Division Multiplexing), which is commonly used in visible light communication, the simulation results show that the multi-LED phase-shifted space-time code can achieve higher transmission rate, and the anti-LED nonlinear performance is better. 3. In order to improve the transmission performance of the system in low-pass frequency-selective channels, the unique decomposable constellation pair (Uniquely Factorable Constellation Pair,UFCP) technique is combined with visible light communication to construct the constellation associated VLC OFDM technique and the constellation associated multi-LED phase-shifted space-time code. The constellation associated VLC OFDM technique correlates the symbols on different subcarriers and demodulates them at the receiver, which improves the anti-frequency selection performance of the system. On this basis, the maximum likelihood detection method of VLC OFDM based on constellation correlation is presented, and the average Euclidean distance gain obtained by using constellation correlation technique in VLC OFDM is analyzed. By combining UFCP technology with block concatenated phase-shifted space-time codes, a constellation associated block concatenated phase-shifted space-time codes is proposed. The essence of the proposed codes is to associate the symbols of different branches of block concatenated phase-shifted space-time codes and demodulate them to gain. Numerical simulation results show that the signal-to-noise ratio gain of 0.8-1.5 dB can be obtained by using constellation correlation method. Aiming at the typical application of indoor visible light communication, two kinds of baseband transmission system of visible light communication are designed and implemented. First, the prototype system of 50 Mbit/s visible light communication chip is designed and implemented to meet the application requirement of medium and low speed visible light communication. The system structure and function index of the visible light baseband chip are given. The realization flow of each module on FPGA is introduced in detail. Secondly, for the application of high speed visible light communication, using the concatenated phase shift space-time coding proposed in this paper, using the three cores of RGB LED to realize the superposition transmission of three signals, the 800 Mbit/s off-line processing system is designed and implemented.
【学位授予单位】：解放军信息工程大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN929.1
本文编号：2351883
[Abstract]:Visible light communication (Visible Light Communication,VLC) combines lighting and communication organically, using the new spectrum resources of visible light, relying on the widely covered lighting lamps, in order to alleviate the "spectrum tension" of wireless communication. Such issues as "deep coverage" and "green energy conservation" provide new means. Aiming at the problem of high speed transmission of visible light communication, this paper focuses on the phase shift associated space-time coding technology. The main research contents and results are summarized as follows: 1. The DC and AC transmission characteristics of commercial lighting LED (Light Emitting Diodes) are measured and analyzed. The voltage-current and current-luminous flux conversion characteristics of LED are measured. The nonlinear characteristics of LED are modeled by polynomial, and the influence of nonlinearity on high-order modulation signals is analyzed. The amplitude-frequency response curves of three color LED cores are measured, and the time-domain and frequency-domain preequalization methods are given. 2. In order to solve the problem of limited transmission rate of single LED, a method of superposition transmission with multiple LED phase shift is proposed, which can increase the transmission rate exponentially. A multi-input and single-output transmission system is constructed by using the natural linear superposition of light in space after relative phase shift. The block phase shift space-time code is designed and its fast detection algorithm is given. Theoretical analysis shows that the spectrum efficiency is proportional to the number of LED cores and can reach full diversity in fading channels. In order to further improve the spectral efficiency, a block concatenated phase-shifted space-time code is constructed on the basis of block phase-shifted space-time code. A precoding method to prevent error propagation is designed, and its bit error performance is analyzed. Compared with single-channel transmission, block concatenated phase-shifted space-time codes can increase the spectral efficiency to N times (N is the number of LED wicks) and achieve full rate. Compared with OFDM (Orthogonal Frequency Division Multiplexing), which is commonly used in visible light communication, the simulation results show that the multi-LED phase-shifted space-time code can achieve higher transmission rate, and the anti-LED nonlinear performance is better. 3. In order to improve the transmission performance of the system in low-pass frequency-selective channels, the unique decomposable constellation pair (Uniquely Factorable Constellation Pair,UFCP) technique is combined with visible light communication to construct the constellation associated VLC OFDM technique and the constellation associated multi-LED phase-shifted space-time code. The constellation associated VLC OFDM technique correlates the symbols on different subcarriers and demodulates them at the receiver, which improves the anti-frequency selection performance of the system. On this basis, the maximum likelihood detection method of VLC OFDM based on constellation correlation is presented, and the average Euclidean distance gain obtained by using constellation correlation technique in VLC OFDM is analyzed. By combining UFCP technology with block concatenated phase-shifted space-time codes, a constellation associated block concatenated phase-shifted space-time codes is proposed. The essence of the proposed codes is to associate the symbols of different branches of block concatenated phase-shifted space-time codes and demodulate them to gain. Numerical simulation results show that the signal-to-noise ratio gain of 0.8-1.5 dB can be obtained by using constellation correlation method. Aiming at the typical application of indoor visible light communication, two kinds of baseband transmission system of visible light communication are designed and implemented. First, the prototype system of 50 Mbit/s visible light communication chip is designed and implemented to meet the application requirement of medium and low speed visible light communication. The system structure and function index of the visible light baseband chip are given. The realization flow of each module on FPGA is introduced in detail. Secondly, for the application of high speed visible light communication, using the concatenated phase shift space-time coding proposed in this paper, using the three cores of RGB LED to realize the superposition transmission of three signals, the 800 Mbit/s off-line processing system is designed and implemented.
【学位授予单位】：解放军信息工程大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN929.1
【参考文献】
相关期刊论文 前1条
1 迟楠;王源泉;王一光;黄星星;陆肖元;;Ultra-high-speed single red green blue light-emitting diode-based visible light communication system utilizing advanced modulation formats[J];Chinese Optics Letters;2014年01期
，本文编号：2351883
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