白光LED可见光通信的若干关键技术研究

发布时间：2018-05-20 09:47

本文选题：正交频分复用技术 + 循环前缀　；参考：《华北水利水电大学》2016年硕士论文

【摘要】：随着“智能”的提出,可见光通信成了当今社会的主题,许多人在想:在飞机上如何打发时间?在飞机上又如何能处理紧急的公务?在医院如何能在没有电磁干扰的情况下做手术?在矿井下如何能在不使用电磁信号的情况下,进行通信?为了解决这些问题,人们想了很多办法,可见光通信应运而生。在光通信时,由于没有电磁的产生,人们无需担心由于电磁的干扰影响飞机的正常运行;也无需担心在医院影响手术;还无需担心由于电磁的作用产生火花,使人们遭遇矿难。由于种种的原因,可见光通信的优势更能凸显出来,所以可见光通信成为通信研究热点。目前在可见光中调制方式有多种,例如:频移键控调制、幅移键控调制、相移键控调制、正交频分复用(OFDM)调制等等。OFDM调制技术的提出解决了许多调制解决不了的问题。比如:由于其正交性节省了带宽;在OFDM中加入循环前缀之后解决了码间干扰与符号间干扰的问题。本文在前人的基础之上,对通信做出进一步的研究,通过进一步的学习在各种调制之中,选择了以OFDM调制方式来进行调制解调。在可见光通信中,基于OFDM调制存在符号间的干扰(ISI),为了去除信号中符号间的干扰,在OFDM系统中加入了循环前缀(CP),在循环前缀中利用同步算法,并对其进行进一步分析研究,此文的算法为最大似然估计算法,之后对判决反馈时域均衡算法做了研究。加上时域均衡的循环前缀,由于属于非线性的均衡器,而非线性的误码率比线性的误码率小。而判决反馈均衡器在循环前缀中的应用,可以减少因多径衰落与信道内的不平稳所带来的码间干扰。在文中主要以MATLAB为仿真手段,在simulink中建立模块,仿真得出OFDM的调制解调仿真图。通过仿真分析得知:当信噪比小时,加性高斯白噪声的加入会严重影响信号的传输;当信噪比较大时,信道间的干扰会严重影响信号的传输。
[Abstract]:With the introduction of "intelligence", visible light communication has become the theme of today's society, many people are thinking: how to spend time on the plane? How can I handle urgent business on the plane? How can I operate in a hospital without electromagnetic interference? How can I communicate under a mine without using electromagnetic signals? In order to solve these problems, people have come up with a lot of methods, visible light communication came into being. In optical communication, because there is no electromagnetic generation, people do not have to worry about the normal operation of aircraft due to electromagnetic interference, nor do they have to worry about the operation in hospital. Due to various reasons, the advantages of visible light communication are more prominent, so visible light communication has become a research hotspot. At present, there are many modulation methods in visible light, such as frequency shift keying modulation, amplitude shift keying modulation, phase shift keying modulation, quadrature frequency division multiplexing OFDM modulation and so on. For example, because of its orthogonality, bandwidth is saved, and the problem of inter-symbol interference and inter-symbol interference is solved by adding cyclic prefix to OFDM. On the basis of previous studies, this paper makes further research on communication. Through further learning, we choose OFDM modulation to modulate and demodulate. In the visible light communication, in order to remove the intersymbol interference in the signal, the cyclic prefix is added to the OFDM system based on the OFDM modulation, and the synchronization algorithm is used in the cyclic prefix, which is further analyzed and studied. The algorithm in this paper is the maximum likelihood estimation algorithm, and then the decision feedback time domain equalization algorithm is studied. With the cyclic prefix of time domain equalization, the nonlinear bit error rate is smaller than the linear one because of the nonlinear equalizer. The application of decision feedback equalizer in cyclic prefix can reduce the inter-symbol interference (ISI) caused by multipath fading and unsteadiness in the channel. In this paper, MATLAB is used as the simulation method, the module is built in simulink, and the simulation diagram of OFDM modulation and demodulation is obtained by simulation. The simulation results show that the additive Gao Si white noise will seriously affect the signal transmission when the SNR is small, and the inter-channel interference will seriously affect the signal transmission when the signal-to-noise ratio is large.
【学位授予单位】：华北水利水电大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TN929.1

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