可见光通信系统的定时同步技术研究

发布时间：2018-04-27 10:40

本文选题：可见光通信 + OFDM　；参考：《哈尔滨理工大学》2017年硕士论文

【摘要】：随着互联网技术的快速发展,人们对数据的传输速率和传输质量有了更高的要求。但是,在目前的射频通信领域中,因为数据信息传输需求迅速增加,让有限的频谱资源更加短缺。因此,一种利用LED闪烁信号来进行传输数据信息的通信方式被提出,其兼具照明和通信双重功能,我们称之为可见光通信,它具有无需频带资源、对人体没有伤害以及保密性强等优点。同步技术会直接影响可见光通信系统的整体性能。若是同步估计不够准确,不仅不能可靠的进行传输信息,而且也不能在系统的接收端恢复出所需要的信息,故可见光通信系统要想正常的工作,同步是其基础。本文主要研究定时同步技术。本文在分析了可见光通信的特点和现状后建立了其系统模型。其中,在LED阵列的驱动模块,设计的电源系统具有低耗、稳定、高效以及使用寿命长等优点,其可以认为是一种驱动LED阵列的理想电源;采用的调制方式是16QAM-OFDM,其易于抑制多径效应,不仅可以减少同步算法的设计复杂程度,而且还可以增加频带的利用率。在分析了定时同步的经典算法SC算法、Minn算法以及Park算法之后,再结合目前此领域的大量文献,发现经典算法存在“相关峰平台”现象以及次峰干扰影响符号精确定位等,目前研究成果存在实时性不佳以及抗扰性弱等缺陷。本文针对它们的不足之处,提出了一种定时同步的改进算法。最后,将SC算法、Minn算法、Park算法和改进算法应用到可见光通信系统模型中,进行定时估计的仿真测试。采用定时度量函数和字符串的定时估计均方差曲线对比以及数据分析,图片的视觉差异,检验改进算法的可行性。对仿真结果分析后证明,相比于上述经典算法,无论在AWGN还是RMF信道中,本文提出的改进算法能够精准定位且能保持良好的实时性和抗扰性。尤其在低信噪比的条件下,改进算法的定时估计均方差接近0(为0.041),而基础算法的均方差远大于改进算法。本文的研究成果,在可见光通信领域中具有良好的应用前景。
[Abstract]:With the rapid development of Internet technology, people have higher requirements for data transmission rate and transmission quality. However, in the field of radio frequency communication, the demand for data transmission is increasing rapidly, which makes the limited spectrum resources more scarce. Therefore, a communication mode using LED flicker signals to transmit data information is proposed. It has both lighting and communication functions, which we call visible light communication, and it has no frequency band resources. No harm to the human body and strong confidentiality and other advantages. Synchronization technology will directly affect the overall performance of visible light communication systems. If the synchronization estimation is not accurate enough, not only can't transmit the information reliably, but also can't restore the needed information in the receiver of the system, so synchronization is the basis of the visible light communication system if it wants to work normally. This paper mainly studies timing synchronization technology. After analyzing the characteristics and present situation of visible light communication, the system model is established in this paper. In the driving module of LED array, the designed power supply system has the advantages of low consumption, stability, high efficiency and long service life, which can be considered as an ideal power supply for driving LED array. The modulation mode is 16QAM-OFDM, which is easy to suppress the multipath effect, which not only reduces the design complexity of the synchronization algorithm, but also increases the utilization rate of the frequency band. After analyzing the classical algorithm of timing synchronization, SC algorithm and Park algorithm, and combining with a large number of literatures in this field, it is found that the classical algorithm has the phenomenon of "correlation peak platform" and the influence of sub-peak interference on the accurate location of symbol, and so on. At present, the research results have some defects, such as poor real-time performance and weak immunity. In this paper, an improved timing synchronization algorithm is proposed for their shortcomings. Finally, the SC algorithm, Minn algorithm, Park algorithm and the improved algorithm are applied to the visible light communication system model, and the simulation test of timing estimation is carried out. Using timing measure function and string timing estimation mean square error curve contrast and data analysis, image visual difference, to test the feasibility of the improved algorithm. After analyzing the simulation results, it is proved that the proposed improved algorithm can locate accurately and maintain good real-time and immunity in both AWGN and RMF channels, compared with the classical algorithms mentioned above. Especially under the condition of low signal-to-noise ratio, the RMS of the improved algorithm is close to 0 (0.041), while the RMS of the basic algorithm is much larger than that of the improved algorithm. The research results of this paper have a good application prospect in the field of visible light communication.
【学位授予单位】：哈尔滨理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN929.1

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