多载波与可见光通信系统的研究

发布时间：2018-07-05 13:46

本文选题：多载波 + 信噪比　；参考：《北京邮电大学》2015年硕士论文

【摘要】：随着信息化的不断深入,人类对网络的需求不断增加,通信业务呈现爆炸式增长。不断增加的设备数量、更多的互联网用户、更快的宽带速度、更多视频导致了IP流量的暴增,这些因素加大了对骨干网传输容量和传输速率的要求。为了提高传输容量及效率,传输系统在发送端大多采用多个激光器,然而由于各个激光器指标不能做到完全一致,使实验系统稳定性受到影响；而且大量激光器的使用,也不利于传输系统的商用化。因此使用稳定的多载波光源做发射机成为了研究热点。在众多产生多载波光源的方案中,基于循环频移结构的方案产生的多载波光源具有稳定、平坦度高的优点,且产生子载波数量多,非常适合太比特传输系统,成为主要研究方案；但是由于其循环结构特性,造成噪声累积,降低了产生多载波光源的信噪比,影响多载波光源的质量。因此如何进一步提高信噪比以适用于高速传输系统成为了重点研究方向。由于全球互联网用户激增及用户使用无线接入技术的普及,现有无线接入技术在速率、容量、安全性、复用性等诸多方面将遭遇严重挑战。可见光通信技术作为一种新兴的无线接入技术,由于其通信与能量复用的特点,拥有广阔的应用前景；与此同时兼具波段免费、方便安全的特性,越来越受到学者们重视。当前可见光通信系统中主要利用LED作为发射机,完成通信与照明功能;接收端采用光电检测器接收光信号,仅仅完成通信功能。这种是一种功能不对称的系统结构,在造成能量的浪费同时又难以实用化,限制了可见光通信系统研究的发展。为解决以上问题,设计易于商用化的新型可见光通信系统结构,成为了重要研究方向根据以上问题,本论文将从多载波和可见光通信系统两部分展开研究工作。主要工作分为以下几个方面： 1.从有线和无线两方面阐述光通信的发展现状和研究意义。 2.分析基于循环频移结构产生多载波光源方案的原理及系统结构,同时从激光器线宽和ASE噪声累积两个方面研究了噪声累积对多载波光源性能的影响。 3.对时延干涉仪的基本原理进行研究,进而提出了产生多载波光源的改进型方案。依次从理论分析、仿真验证、实验搭建完成对改进型结构功能实现的验证工作。 4.研究可见光通信基础理论及以太网和串口通信协议。仿真验证基于FPGA的MAC控制器开发和基于FPGA的串口通信开发,并将串口通信协议应用于可见光通信系统中。 5.分析太阳能电池工作原理,由此提出了功能对称的可见光通信系统,进而搭建实验平台验证系统方案可行。综上所述,本论文将分别研究多载波和可见光通信系统两部分。多载波方面主要研究了基于循环频移结构产生多载波光源的方案原理,噪声累积对所产生多载波性能的影响及影响噪声累积的主要因素；通过分析研究时延干涉仪特性,提出了一种改进型多载波产生方案,有效提高了多载波光源质量。可见光通信系统方面研究了系统基础理论及相关通信协议,完成了基础可见光通信系统搭建；进而研究太阳能电池原理并将其应用于可见光通信系统中,实现收发两端均能够达到通信和能量复用功能,实验验证了提出的功能对称的可见光通信系统方案可行性。
[Abstract]:With the deepening of the information technology , the demand of human to the network is constantly increasing , and the communication service presents explosive growth . The increasing number of devices , more Internet users , faster broadband speed , and more video result in an increase in IP traffic . These factors increase the demand for the transmission capacity and transmission rate of the backbone network .

in ord to improve that transmission capacity and efficiency , a plurality of lasers are adopt at the transmitting end of the transmission system , but the stability of the experimental system is influenced due to the fact that the indexes of each laser cannot be completely consistent ;
in the scheme of generating the multi - carrier light source , the multi - carrier light source generated by the scheme based on the cyclic frequency shift structure has the advantages of stable and flatness and large number of sub - carriers , is very suitable for the terahertz transmission system and becomes the main research scheme ;
However , due to its cyclic structure characteristics , noise accumulation is reduced , the signal - to - noise ratio of multi - carrier light source is reduced , and the quality of multi - carrier light source is affected . Therefore , it is important to improve the signal - to - noise ratio so as to be suitable for high - speed transmission system .

Due to the proliferation of global Internet users and the popularization of wireless access technologies by users , the existing wireless access technology will encounter serious challenges in many aspects , such as rate , capacity , security and reusability . Visible light communication technology is a new wireless access technology . Due to its characteristics of communication and energy reuse , it has a wide application prospect .
At the same time , it has the characteristics of free , convenient and safe band , and more and more scholars pay more attention .

In the current visible light communication system , the LED is mainly used as a transmitter to finish the communication and lighting function , and the receiving end adopts a photoelectric detector to receive the optical signal , and only completes the communication function .

According to the above problems , the thesis will carry out research work from two parts of multi - carrier and visible light communication system . The main work is divided into the following aspects :

1 . The development status and significance of optical communication are discussed from both wired and wireless aspects .

2 . The principle and system structure of multi - carrier light source scheme are analyzed based on the cyclic frequency shift structure , and the influence of noise accumulation on the performance of multi - carrier light source is studied from two aspects of laser linewidth and ASE noise accumulation .

3 . The basic principle of the time delay interferometer is studied , and the improved scheme for generating the multi - carrier light source is put forward . From the theoretical analysis , the simulation verification and the experiment , the verification of the function of the improved structure is completed .

4 . Research the basic theory of visible light communication and the communication protocol of Ethernet and serial port . Simulation verifies the development of MAC controller based on FPGA and serial communication development based on FPGA , and applies serial communication protocol to visible light communication system .

5 . The working principle of the solar cell is analyzed , and the function - symmetrical visible - light communication system is put forward , and then the scheme of the experiment platform verification system is feasible .

In conclusion , this thesis will study two parts of multi - carrier and visible - light communication systems , which mainly study the scheme principle of multi - carrier light source based on cyclic frequency shift structure , the influence of noise accumulation on multi - carrier performance and the main factors affecting noise accumulation .
By analyzing the characteristics of delay interferometer , an improved multi - carrier generation scheme is proposed , which improves the quality of multi - carrier light source effectively .
In this paper , the principle of solar cell and its application in the visible light communication system are studied . The communication and energy multiplexing function can be realized at both ends of the transceiver , and the feasibility of the proposed scheme is verified .
【学位授予单位】：北京邮电大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN929.1

【参考文献】