可见光高速通信叠加编码技术研究
发布时间：2018-09-17 11:25
【摘要】：可见光通信(VLC)是利用LED作为通信信源,光电检测器PD作为接收器的一种无线通信方式。VLC作为未来潜在的高速无线通信技术,更高速率成为了通信界不懈的追求。由于光通信采用的强度调制/直接检测方式以及商用LED调制带宽较低、电光转换非线性等因素,单个灯芯的传输速率往往受限。针对以上问题,本文对发送端为单个灯具内的多个灯芯、接收端为单一PD构成的叠加传输系统展开分析。主要研究工作如下:1.针对单一LED速率受限问题,提出了采用灯具内多个灯芯并行叠加的传输方法,以成倍提升可见光通信的传输速率。本文在室内视距链路LOS下展开分析和研究,由于VLC采用的商用LED具有电调制带宽有限、电光转换线性区间较窄等缺点,以及受LED和PD物理特性限制所采用的强度调制/直接检测方式制约,使得LED速率受限;正常的照明是由多个灯芯协作完成,并且室内VLC中信噪比条件较优。由此提出了一种多灯芯叠加传输方案,该方式下采用K个灯芯时,系统的传输速率可以等效的提升K倍。2.为了检测多灯芯会聚叠加信号,采用叠加编码调制(SCM)技术,以驱动电压差异为检测条件,建立了可见光通信叠加编码调制(VLC-SCM)模型,给出了联合检测算法。首先提出了VLC-SCM系统发送端并行传输结构;由于LED的瞬时驱动电压非负,因此在LED前加上一个直流偏置,提出了基于开关键控OOK调制的数据处理方式;在Lambertian模型基础上对多灯芯系统的信道进行了研究,得出了叠加传输系统并不依赖信道差异性来区分数据,为了检测叠加后多灯芯会聚光强信号,在发送端引入各灯芯驱动电压差异。最后针对多灯芯约束、编码约束,提出了基于OOK的接收端联合检测算法。仿真验证了VLC-SCM多灯芯叠加传输系统较好的高速传输性能。3.为了提升叠加传输系统的抗非线性性能,采用交织分多址(IDMA)技术,以交织器差异为检测条件,建立了可见光通信交织分多址(VLC-IDMA)传输模型,给出了串并行两种检测算法和快速性能估计算法。分析了系统的发送传输结构,采用交织器这一唯一差异来检测会聚光强信号。提出了采用低码率编码时为全+1的重复码结构,研究了接收端串行和并行两种检测方式,指出在系统性能和实现复杂度上要有所权衡;接着给出了一种多灯芯叠加传输系统性能估计算法以快速预测多灯芯系统的性能。仿真验证了VLC-IDMA多灯芯叠加系统优异的高速传输性能和抗非线性性能。4.依据驱动电压差异、交织器差异和LED的非线性特性,提出了一种联合功率分配方案,提升了系统的传输效率和检测性能。针对单一驱动电压差异时LED容易进入非线性区间,单一交织器差异使得编码效率较低,提出了多维差异条件下的叠加系统以提升系统性能。由于灯具内灯芯数目适中,采用的无穷搜索的信噪比演进和规划的联合功率分配符合实际需求。仿真表明该方案使叠加系统中LED电压工作在线性范围内;与低码率的多灯芯恒定驱动电压方案相比,该方案传输效率更高。
[Abstract]:Visible light communication (VLC) is a wireless communication mode using LED as communication source and photoelectric detector PD as receiver. As a potential high-speed wireless communication technology in the future, VLC has become the unremitting pursuit of the communication field. Because of the intensity modulation/direct detection method used in optical communication and the low modulation bandwidth of commercial LED, electricity is used. The transmission rate of a single wick is often limited due to the non-linearity of light conversion. To solve the above problems, this paper analyzes the superimposed transmission system consisting of multiple wicks in a single luminaire at the transmitter and a single PD at the receiver. Line superposition transmission method is used to multiply the transmission rate of visible light communication. In this paper, the analysis and research are carried out under LOS. The commercial LED used in VLC has the shortcomings of limited bandwidth of electric modulation, narrow linear range of electro-optic conversion, and the intensity modulation/direct detection method limited by the physical characteristics of LED and PD. Constraints restrict the LED speed; normal lighting is accomplished by multiple wicks, and the signal-to-noise ratio of indoor VLC is better. A multi-wick overlay transmission scheme is proposed, in which the transmission rate of the system can be increased by K times when K wicks are used. 2. In order to detect multi-wicks overlay signal, overlay is used. Coded modulation (SCM) technology, taking the difference of driving voltage as the detection condition, establishes the VLC-SCM model and gives the joint detection algorithm. Firstly, the parallel transmission structure of the VLC-SCM system is proposed. Because the instantaneous driving voltage of the LED is non-negative, a DC bias is added to the front of the LED, and the on-off detection algorithm is proposed. Based on Lambertian model, the channel of multi-wick system is studied. It is concluded that the superimposed transmission system does not depend on channel difference to distinguish data. In order to detect the signal of multi-wick convergence intensity after superimposition, the difference of wick driving voltage is introduced at the transmitter. In order to improve the anti-nonlinearity performance of VLC-SCM multi-wick overlay transmission system, interleaved multiple access (IDMA) technology was used to establish the visible light communication interleaving under the detection condition of interleaver difference. The transmission model of VLC-IDMA is presented. Two detection algorithms, serial-parallel and fast performance estimation algorithms, are given. The transmission structure of the system is analyzed. The unique difference between interleavers is used to detect the convergent light intensity signal. A repetitive code structure with low bit rate encoding is proposed. The serial and parallel detection methods at the receiver are studied. Then, a performance estimation algorithm for multi-wick superimposed transmission system is proposed to predict the performance of multi-wick system quickly. Simulation results show that the VLC-IDMA multi-wick superimposed system has excellent high-speed transmission performance and Anti-nonlinear performance. 4. Interleaving according to the difference of driving voltage. A joint power allocation scheme is proposed to improve the transmission efficiency and detection performance of the system, which is based on the difference between the drivers and the non-linear characteristics of the LED. The simulation results show that the proposed scheme makes the LED voltage in the superposition system work within the linear range, and the transmission efficiency of the proposed scheme is higher than that of the low bit rate multi-wick constant driving voltage scheme.
【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：2245733
[Abstract]:Visible light communication (VLC) is a wireless communication mode using LED as communication source and photoelectric detector PD as receiver. As a potential high-speed wireless communication technology in the future, VLC has become the unremitting pursuit of the communication field. Because of the intensity modulation/direct detection method used in optical communication and the low modulation bandwidth of commercial LED, electricity is used. The transmission rate of a single wick is often limited due to the non-linearity of light conversion. To solve the above problems, this paper analyzes the superimposed transmission system consisting of multiple wicks in a single luminaire at the transmitter and a single PD at the receiver. Line superposition transmission method is used to multiply the transmission rate of visible light communication. In this paper, the analysis and research are carried out under LOS. The commercial LED used in VLC has the shortcomings of limited bandwidth of electric modulation, narrow linear range of electro-optic conversion, and the intensity modulation/direct detection method limited by the physical characteristics of LED and PD. Constraints restrict the LED speed; normal lighting is accomplished by multiple wicks, and the signal-to-noise ratio of indoor VLC is better. A multi-wick overlay transmission scheme is proposed, in which the transmission rate of the system can be increased by K times when K wicks are used. 2. In order to detect multi-wicks overlay signal, overlay is used. Coded modulation (SCM) technology, taking the difference of driving voltage as the detection condition, establishes the VLC-SCM model and gives the joint detection algorithm. Firstly, the parallel transmission structure of the VLC-SCM system is proposed. Because the instantaneous driving voltage of the LED is non-negative, a DC bias is added to the front of the LED, and the on-off detection algorithm is proposed. Based on Lambertian model, the channel of multi-wick system is studied. It is concluded that the superimposed transmission system does not depend on channel difference to distinguish data. In order to detect the signal of multi-wick convergence intensity after superimposition, the difference of wick driving voltage is introduced at the transmitter. In order to improve the anti-nonlinearity performance of VLC-SCM multi-wick overlay transmission system, interleaved multiple access (IDMA) technology was used to establish the visible light communication interleaving under the detection condition of interleaver difference. The transmission model of VLC-IDMA is presented. Two detection algorithms, serial-parallel and fast performance estimation algorithms, are given. The transmission structure of the system is analyzed. The unique difference between interleavers is used to detect the convergent light intensity signal. A repetitive code structure with low bit rate encoding is proposed. The serial and parallel detection methods at the receiver are studied. Then, a performance estimation algorithm for multi-wick superimposed transmission system is proposed to predict the performance of multi-wick system quickly. Simulation results show that the VLC-IDMA multi-wick superimposed system has excellent high-speed transmission performance and Anti-nonlinear performance. 4. Interleaving according to the difference of driving voltage. A joint power allocation scheme is proposed to improve the transmission efficiency and detection performance of the system, which is based on the difference between the drivers and the non-linear characteristics of the LED. The simulation results show that the proposed scheme makes the LED voltage in the superposition system work within the linear range, and the transmission efficiency of the proposed scheme is higher than that of the low bit rate multi-wick constant driving voltage scheme.
【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
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