基于LDPC码的可见光通信系统性能研究

发布时间：2018-01-10 05:16

本文关键词：基于LDPC码的可见光通信系统性能研究　出处：《哈尔滨工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：可见光通信(VLC)技术作为一项近几年兴起的新型无线接入技术,以其功耗低、频带宽、保密性强和无电磁污染等优点,得到了世界范围内的关注。随着移动互联和家庭智能的迅速发展,可见光通信将在其中扮演重要角色。目前,可见光通信系统的研究主要集中在调制技术、信道均衡技术以及提高传输速率和可靠性等方面。随着可见光通信关键技术和芯片的快速研发,未来的可见光通信将朝着超宽带,超高速,大吞吐量,大覆盖范围和高可靠性的方向发展,包括移动大数据和高清影像等对误码性能要求高的多媒体业务。因此必须寻找一种吞吐量大,适合高速率通信和性能优异的可见光通信信道编码方案。本文主要研究了LDPC码在可见光通信中的应用,首先,深入分析了可见光通信系统结构和可见光信道模型,对可见光信道特性进行了理论分析。接着,仿真分析了信道冲击响应等关键参量,并得出了可见光信道的近似数学模型。同时,对光源布局进行了理论分析,通过对不同房间的实验仿真,提出了最佳光源布局的原则,并证明了最佳光源布局下的信号接收质量明显提高。之后,分析了IEEE802.15.7标准RS码的优缺点,阐述了可见光通信纠错码构造原则。通过对IEEE802.16e标准LDPC码的深入研究,构造了一种适合可见光通信的QC-LDPC码,找到了其快速编码方法,并对其进行四环检验,仿真结果表明,校验矩阵不存在四环。接着,研究了LDPC码各种译码方法,基于BP算法和MS算法提出了一种译码改进算法,并将该算法应用到搭建的可见光通信系统仿真模型中,通过对通信平台网格化处理找到了信道条件最差的信道,在此基础上,对乘性因子和迭代次数对系统误码性能的影响展开了研究,根据仿真结果确定了改进译码算法中的迭代次数和最佳乘性因子。最后,对LDPC码各译码算法的误码性能进行仿真,并计算各译码算法的复杂度,结果表明,改进译码算法在算法复杂度和误码性能方面实现了较好的优化折中,在最佳光源布局下实现了房间内任意一点的可靠通信,证明了该码能够满足可见光通信信道编码的构造原则,是一种适合可见光通信的信道编码。
[Abstract]:As a new wireless access technology, visible light communication (VLC) technology has many advantages, such as low power consumption, high frequency bandwidth, strong confidentiality and no electromagnetic pollution. With the rapid development of mobile interconnection and home intelligence, visible light communication will play an important role. At present, the research of visible light communication system is mainly focused on modulation technology. With the rapid development of the key technologies and chips of visible light communication, the future visible light communication will move towards ultra-wideband, ultra-high speed and large throughput. Large coverage and high reliability development, including mobile big data and high-definition video and other high performance requirements for multimedia services, so we must look for a high throughput. This paper mainly studies the application of LDPC code in visible light communication. The structure of visible light communication system and the model of visible light channel are deeply analyzed, and the characteristics of visible light channel are theoretically analyzed. Then, the key parameters such as channel impulse response are simulated and analyzed. The approximate mathematical model of visible light channel is obtained. At the same time, the theory of light source layout is analyzed, and the principle of optimal light source layout is put forward through the experiment simulation of different rooms. It is proved that the signal receiving quality is improved obviously under the optimal light source layout. After that, the advantages and disadvantages of IEEE802.15.7 standard RS code are analyzed. The construction principle of error-correcting code for visible light communication is expounded. A kind of QC-LDPC code suitable for visible light communication is constructed by deeply studying the IEEE802.16e standard LDPC code. The fast coding method is found, and the four-ring test is carried out. The simulation results show that there are no four rings in the check matrix. Then, various decoding methods of LDPC codes are studied. An improved decoding algorithm based on BP algorithm and MS algorithm is proposed and applied to the simulation model of visible light communication system. The channel with the worst channel condition is found through the grid processing of the communication platform. On this basis, the effects of multiplicative factors and iterations on the error performance of the system are studied. According to the simulation results, the iterative times and the best multiplicative factor of the improved decoding algorithm are determined. Finally, the error performance of each decoding algorithm of LDPC codes is simulated, and the complexity of each decoding algorithm is calculated. The results show that the improved decoding algorithm achieves a better compromise in terms of algorithm complexity and error rate performance, and realizes reliable communication at any point in the room under the optimal light source layout. It is proved that this code can meet the construction principle of channel coding for visible light communication and is a channel coding suitable for visible light communication.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN929.1;TN911.22

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