可见光通信中的空间编码调制技术研究

发布时间：2018-02-09 01:57

本文关键词： 可见光通信光空间调制广义光空间调制功率分配信道编码　出处：《东南大学》2016年硕士论文　论文类型：学位论文

【摘要】：作为对传统射频通信(Ratio Frequency, RF)的重要补充,可见光通信技术(Visual Light Commu-nications, VLC)近年来已经成为无线通信领域的研究热点。由于照明设备几乎遍及生活的每个角落,通过照明设备进行无线通信是一种有效而可行的无线通信方案。相较于传统的射频通信,可见光通信具有节能环保、绿色健康、保密性高、未认证频谱资源丰富等一系列优点。但是,受照明用LED器件的开关速度影响,可见光通信系统传输带宽受限,高效利用可见光通信系统的频谱资源十分重要。由于实际的照明系统通常采用多个LED光源组成阵列以提供充足的照明,多输入多输出(Multiple Input Multiple Output, MIMO)传输方案在可见光通信领域受到了广泛关注和研究。空间调制(Spatial Modulation, SM)技术正是一种将MIMO传输技术与传统数字调制技术相结合的调制方式,通过将传统的数字调制星座扩展到空间维度,来提升通信系统的频谱效率。在空间调制系统中存在多个空间上相互隔离的发射机,但同一时刻系统只允许其中一个发射机处于工作状态,从而实现通过工作的发射机序号来传输额外的比特信息。这种调制方案通过使用多个发射机来提升通信系统的频谱效率并完全避免了各个发射机之间的信道间干扰(Inter-Channel Interference, ICI),能很好地适用于可见光通信系统。本文主要就是对可见光通信中空间调制技术进行了研究。本论文首先对可见光通信系统做了总体性的阐述,包括系统结构、光发射机和接收机器件、室内可见光信道模型以及常用的调制方式等。在此基础上介绍了可见光通信系统中常用的三种MIMO传输方式：重复编码(Repetition Coding, RC)、空间复用(Spatial Multiplexing, SMP)和空间调制,并分析比较了这三种MIMO传输技术的基本原理和它们各自的特点,通过仿真比较了这三种方案的误比特率(Bit Error Rate, BER)性能。其次,本论文接着重点探讨了光空间调制(Optical Spatial Modulation, OSM)方案的系统特性,分析了光空间调制系统的优势和缺陷。针对标准光空间调制的系统性能在强相关信道条件下会急剧恶化的缺陷,本文提出了一种新型的广义光空间调制(Generalized Optical Spatial Modulation, GOSM)方案,并通过性能仿真验证了广义光空间调制在强相关信道条件下对系统性能的提升。在此基础上,进一步深入分析和讨论了光空间调制系统中空间域星座和信号域星座各自扮演的角色以及它们之间的相互作用。随后,本论文重点研究了光空间调制系统中的功率分配(Power Allocation, PA)问题。简要介绍了在光空间调制中引入功率分配的基本原理和具体实现方法,并对几种常用的功率分配算法进行了分析比较。在此基础上,依据光空间调制的系统性能与信号最小欧氏距离之间的关系,经过一定的近似简化处理,提出一种基于凸优化的功率分配方案。相较于常用的光空间调制功率分配方案,基于凸优化的功率分配方案优化目标更加明确,经功率分配后的光空间调制的系统性能更好,仿真结果也进一步验证了这一结论。最后,本论文对结合信道编码的光空间调制系统进行了讨论。对目前空间调制系统中常用的信道编码进行了介绍,主要包括卷积码和LDPC码。以此为基础,进一步分析讨论了光空间调制中的比特交织编码调制(Bit-Interleaved Coded Modulation, BICM)方案,并给出了基于LDPC码编码空间调制系统的EXIT门限分析方法。此外,论文还对广义光空间调制中的信道编码问题进行了分析讨论。
[Abstract]:As to the traditional radio frequency communication (Ratio Frequency RF) is an important supplement, visible light communication technology (Visual Light Commu-nications, VLC) in recent years has become a hot research topic in the field of wireless communication. Because every corner of the lighting equipment almost throughout life, through the lighting equipment for wireless communication is an effective and feasible scheme for wireless communication. Compared with the traditional radio frequency communication, visible light communication with energy conservation and environmental protection, green health, high confidentiality, unauthorized rich spectrum resources and a series of advantages. However, the switching speed of LED device with lighting effects, visible light communication system transmission bandwidth, efficient use of spectrum resources of visible light communication system is very important because. The actual lighting system usually adopts a plurality of LED light source array to provide adequate lighting, multiple input multiple output (Multiple Input Multiple Output, MIMO). Transmission scheme has attracted extensive attention and research in visible light communication field. The spatial modulation (Spatial Modulation SM) technology is a kind of modulation mode MIMO transmission technology and traditional digital modulation technology combination, the digital modulation constellation is extended to the traditional spatial dimension, to improve the spectrum efficiency of communication system. The presence of transmitter a plurality of spatially separated spatially modulation system, but at the same time the system allows only one transmitter in the work of the state, so as to realize the transmission of extra bits of information through a number of transmitter work. This modulation scheme by using multiple transmitters to improve the spectrum efficiency of communication system and completely avoid various channels the interference between the transmitter (Inter-Channel Interference, ICI), is well suited for visible light communication system. This paper is mainly on visible light communication In the spatial modulation technique is studied. This paper first makes a general description of the visible light communication system, including system structure, optical transmitter and receiver devices, indoor visible light channel model and common modulation methods. Based on the introduction of three kinds of commonly used MIMO transmission in visible light communication system. Repeat encoding (Repetition Coding, RC (Spatial Multiplexing), spatial multiplexing and spatial modulation, SMP), and analyzes the basic principle of the three MIMO transmission technology and their characteristics, the bit error of the three methods were compared through simulation (Bit Error Rate, BER) performance. Secondly, the then this paper focuses on the spatial light modulation (Optical Spatial, Modulation, OSM) system scheme, analyzes the advantages and disadvantages of space light modulation system. According to the standard optical spatial modulation system performance in strong Defect related channel conditions will worsen sharply, this paper proposes a new generalized optical spatial modulation (Generalized Optical Spatial Modulation, GOSM), and generalized optical spatial modulation in highly correlated channel conditions to enhance system performance is verified by simulation. On this basis, further in-depth analysis and discussion of each other interaction between optical spatial modulation system in spatial domain domain constellation and signal constellation and their respective roles. Then, this paper focuses on the study of power distribution system in optical spatial modulation (Power Allocation, PA). The paper briefly introduces the principle of power distribution in the space light modulation is introduced and the concrete realization method. And several common power allocation algorithms are analyzed and compared. On this basis, according to the system performance and signal the minimum Euclidean distance of optical spatial modulation The relationship between the through approximation will be simplified, proposed a power allocation scheme based on convex optimization. Compared with common optical spatial modulation and power allocation scheme, convex optimization power allocation scheme based on the optimization objectives more clearly, the light modulation of the space power distribution system with better performance, the simulation results also further verified this conclusion. Finally, this paper discusses the spatial light modulation system with channel encoding. The channel encoding commonly used spatial modulation system are introduced, including convolutional codes and LDPC codes. On this basis, further discussed the interleaving encoding modulation optical spatial modulation in bits (Bit-Interleaved Coded Modulation, BICM) scheme, and gives the analysis method of LDPC codes encoding spatial modulation system EXIT based on threshold. In addition, the channel light modulation in generalized space The coding problem is analyzed and discussed.

【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TN929.1

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