正交频分复用（Orthogonal Frequency Divisio

Orthogonal Frequency Division Multiplexing (Orthogonal Frequency Division Multiplexing), abbreviated as OFDM, is one of the multi-carrier modulation methods. This technology requires that the sub-channel bandwidth be included in the original channel bandwidth and be smaller than the original bandwidth. This is done to ensure that the channel can be better balanced. <br>OFDM has become the main core technology used in the third-generation mobile communication technology and the fourth-generation mobile communication technology. At present, due to the popularity of 5G and the 5G technology's higher spectral efficiency requirements for high-speed data, we have to Focusing on the existing technology is also due to the advantages of OFDM technology, so we need to introduce new waveforms on the basis of OFDM, so that it can better meet the further needs of 5G communications. But in fact OFDM is the largest The advantage is that it can make the orthogonality of the subcarriers reasonably satisfied. If the orthogonality is not satisfied, there will be mutual interference, which further leads to the advantage of the spectrum resource utilization of the OFDM system cannot be reflected, so the accurate CFO carrier frequency offset Estimates have important practical research significance. <br>The main direction of this paper is based on several typical carrier frequency offset estimation algorithms that have been proposed by others a long time ago, including: (1) the basic principles of OFDM system and the salient features of the system, (2) detailed analysis DFT implementation method in OFDM system, serial-to-parallel conversion, guard interval and cyclic prefix. (3) Introduces how the carrier frequency deviation will affect the OFDM system, and also includes the causes of frequency offset, etc. (4) Introduces the knowledge about the time variability of the wireless channel multipath effect and channel model. (5) Introduces the related principles and algorithms of frequency domain estimation technology proposed by Moose, as well as the related principles and algorithms of time domain estimation technology based on cyclic prefix CP and carrier frequency offset estimation of OFDM system based on Classen frequency domain carrier frequency offset The relevant principles and algorithm description of the estimation calculation and the simulation experiments of the three algorithms were analyzed and compared.

正交频分复用（Orthogonal Frequency Division Multiplexing），缩写表达成OFDM，它是多载波调制的方式之一。这种技术要求子信道带宽要包括在原来信道带宽内，要比原带宽小，这样做是为了保证能够更好地均衡信道。<br>OFDM成为用于第三代移动通讯技术和第四代移动通讯技术中的主要核心技术，目前，由于5G的普及，再加上5G技术对高速率数据的频谱效率要求更高，使得我们不得不把目光聚集在已有的技术中，也是由于OFDM技术的优势性，使我们需要在OFDM的基础上推出新的波形，使其更好地满足5G通讯的进一步的需求.但实际上OFDM最大的优势就是它可以使子载波正交性得到合理满足,如果不能满足正交性，就会有相互干扰，从而进一步导致OFDM系统的频谱资源利用率的优势则无法体现，所以准确的CFO载波频偏估计具有重要的现实研究意义。<br>本论文主攻方向是基于几个很久以前就被别人提出来过的很典型的载波频偏估计算法，包括了：（1）OFDM系统的基本原理及其系统的显著特征，（2）详尽分析了OFDM系统中的DFT实现方法，串并变换，保护间隔和循环前缀。（3）介绍了载波频率偏差会对OFDM系统带来怎样的影响，同时也包括频偏产生的原因等（4）介绍了无线信道多径效应时变性和信道模型等相关知识。（5）介绍了Moose提出的频域估计技术的相关原理和算法，以及基于循环前缀CP的时域估计技术的相关原理和算法和OFDM系统的载波频偏估计算基于Classen频域的载波频偏估计算的相关原理及算法描述并进行了三种算法的仿真实验，并对其进行了分析和比较。

Orthogonal frequency division multiplexing, abbreviated as OFDM, is one of the methods of multicarrier modulation. This technology requires that the subchannel bandwidth should be included in the original channel bandwidth, which is smaller than the original bandwidth, so as to ensure better channel equalization.<br>OFDM has become the main core technology used in the third generation mobile communication technology and the fourth generation mobile communication technology. At present, due to the popularity of 5g technology, coupled with the higher requirements of 5g technology on the spectral efficiency of high-speed data, we have to focus on the existing technology. Also because of the advantages of OFDM technology, we need to introduce new waveforms on the basis of OFDM It can better meet the further needs of 5g communication. But in fact, the biggest advantage of OFDM is that it can reasonably meet the orthogonality of subcarriers. If it can not meet the orthogonality, there will be mutual interference, which further leads to the advantage of spectrum resource utilization of OFDM system can not be reflected, so accurate estimation of CFO carrier frequency offset has important practical research significance.<br>The main research direction of this paper is based on several typical carrier frequency offset estimation algorithms which have been proposed by others for a long time, including: (1) the basic principle of OFDM system and its remarkable characteristics; (2) the DFT implementation method, serial parallel conversion, protection interval and cyclic prefix in OFDM system are analyzed in detail. (3) This paper introduces the impact of carrier frequency offset on OFDM system, including the causes of frequency offset and so on. (4) it introduces the related knowledge of wireless channel multipath effect time-varying and channel model. (5) This paper introduces the related principle and algorithm of frequency-domain estimation technology proposed by moose, the related principle and algorithm of time-domain estimation technology based on cyclic prefix CP and the related principle and algorithm description of carrier frequency offset estimation calculation based on Classen frequency-domain in OFDM system, and carries out the simulation experiment of three algorithms, and analyzes and compares them.