可见光通信信道估计技术研究

发布时间：2018-02-19 21:39

本文关键词： 可见光通信导频设计信道估计非线性限幅估计　出处：《东南大学》2017年硕士论文　论文类型：学位论文

【摘要】：近年来,随着移动通信技术的飞速发展,第四代移动通信技术已经在绝大部分城市得到了广泛的应用。但移动通信的快速发展也带来了很多的问题,射频频谱资源日益紧张,继续提高数据传输速率的成本越来越高,"绿色科技"的提出也让人们也逐渐开始关注电磁辐射对身体健康的影响,具有丰富频谱资源、绿色健康的可见光通信技术迎来了新的发展机遇。本论文主要针对可见光通信信道估计技术展开研究,包括导频设计、非线性限幅估计以及信道估计等技术,并结合了可见光实测信道进行了仿真,验证了非线性限幅估计及信道估计的性能,还给出了可见光DCO-OFDM通信系统发射机在FPGA上的设计和实现方案。首先,本文介绍了室内可见光DCO-OFDM通信系统的基本原理和系统模型。论文概述了系统的基本电路原理,包括系统中使用的光电器件特性以及接收发射电路原理。然后对室内可见光通信的系统链路进行了建模分析。其次,本文针对室内可见光DCO-OFDM通信系统中的前导设计和非线性限幅估计方法进行了深入地研究。考察了常用的同步序列的性能,对可见光通信系统中使用的基带信号模型和帧结构进行了研究分析,并在此基础上提出了针对系统中非线性限幅情况的前导序列设计方法。基于设计的前导序列,对可见光通信系统中的非线性限幅进行了建模,建立了限幅误差模型、限幅百分比模型以及相应的判决方案,并通过仿真验证了设计的前导序列以及非线性限幅判定方案的性能。接着,本文还研究了可见光DCO-OFDM通信系统的信道估计方法。论文介绍了传统OFDM通信系统常用的信道估计方法,包括基于块状导频的LS、LMMSE以及基于SVD分解的LMMSE信道估计方法,和基于梳状导频的线性插值、变换域插值法,并通过仿真比较了使用第三章设计的前导序列进行信道估计时不同估计方法的性能,同时也给出了非线性限幅情况对信道估计结果的影响。论文还对多色可见光通信系统的信道特性进行了分析,针对其信道特点,本文提出了两种新的导频设计方案和信道估计方法,通过仿真验证了相比于已有的几种导频设计方案,本文提出的方案获得了更好的传输效率和信道估计的精确度。最后,本文介绍了可见光DCO-OFDM通信系统发射机的硬件设计。论文概述了可见光通信系统平台的总体结构,并对实际系统中使用的硬件平台中的器件参数进行了总结。然后着重讨论了发射机在FPGA硬件平台上的设计方案,详细阐述了 CRC编码、扰码、LDPC编码、星座映射、IFFT变换以及插入循环前缀等基带处理部分的具体实现,最终给出了本课题搭建的实际可见光DCO-OFDM通信系统硬件平台的展示。
[Abstract]:In recent years, with the rapid development of mobile communication technology, the 4th generation mobile communication technology has been widely used in most cities. The cost of continuing to improve the rate of data transmission is becoming higher and higher. The introduction of "green technology" has also made people gradually begin to pay attention to the effects of electromagnetic radiation on their health, and they have rich spectrum resources. The green and healthy visible-light communication technology is facing a new development opportunity. This thesis mainly focuses on the channel estimation technology of visible-light communication, including pilot design, nonlinear amplitude limiting estimation and channel estimation, etc. The performance of nonlinear amplitude limiting estimation and channel estimation is verified by the simulation of visible light real time channel. The design and implementation of the transmitter of visible light DCO-OFDM communication system on FPGA are also given. This paper introduces the basic principle and system model of indoor visible light DCO-OFDM communication system, and summarizes the basic circuit principle of the system. It includes the characteristics of photoelectric devices used in the system and the principle of receiving and transmitting circuit. Then, the system link of indoor visible light communication is modeled and analyzed. Secondly, In this paper, the preamble design and nonlinear amplitude limiting estimation methods in indoor visible light DCO-OFDM communication systems are studied. The performance of common synchronization sequences is investigated. In this paper, the baseband signal model and frame structure used in visible light communication system are studied and analyzed. In this paper, the nonlinear limiting model of visible light communication system is modeled, and the limiting error model, limiting percentage model and corresponding decision scheme are established. The performance of the designed preamble sequence and the nonlinear limiting scheme is verified by simulation. Then, the channel estimation method of the visible light DCO-OFDM communication system is studied, and the channel estimation methods commonly used in the traditional OFDM communication system are introduced in this paper. It includes LSS-LMMSE based on block pilot, LMMSE channel estimation based on SVD decomposition, linear interpolation based on comb pilot and transform domain interpolation. The performance of different channel estimation methods using the preamble sequence designed in Chapter 3 is compared by simulation. At the same time, the influence of nonlinear limiting on the channel estimation results is also given. The channel characteristics of multicolor visible light communication system are also analyzed, aiming at the channel characteristics of the multi-color visible light communication system. In this paper, two new pilot design schemes and channel estimation methods are proposed. The simulation results show that the proposed scheme achieves better transmission efficiency and channel estimation accuracy than the existing pilot design schemes. This paper introduces the hardware design of the visible light DCO-OFDM communication system transmitter, and summarizes the overall structure of the visible light communication system platform. Then the design scheme of transmitter on FPGA hardware platform is discussed, and the CRC coding and scrambling code are discussed in detail. The implementation of the constellation mapping Ifft transform and the insertion of cyclic prefix and other baseband processing parts is implemented. Finally, the hardware platform of the actual visible light DCO-OFDM communication system is presented.
【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN929.1

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