目前，世界范围内的高铁速度已普遍达到250km/h，有的甚至已经超过了350km/h。高铁运行速度的加快给高铁移动通信带来一系列的影响，其中影响最大的是多普勒效应，若不采取有效的措施抑制多普勒效应，则会严重影响通信系统的性能。因此研究高铁环境下LTE系统的频偏估计与补偿技术，具有重要的意义。本文主要做了以下几方面工作： 首先，在无线信道传输特性的基础上结合高铁环境的特殊性，研究和分析了高铁信道模型，并搭建了LTE系统仿真平台。 其次，本文分析和比较了数据辅助类频偏估计算法和非数据辅助类频偏估计算法。鉴于基于导频的数据辅助类算法具有捕获速度快、精度高等优点，本文对基于导频的两种算法进行了进一步研究，分别是子帧间不相关算法和子帧间相关算法。仿真结果表明子帧间相关算法的频偏估计范围大，比较适用于高铁环境。但是当高铁通信链路质量较差时，频偏过大，采用子帧间相关算法无法对上行接收数据的频偏进行实时跟踪校正。尤其是当多普勒频偏发生正负跳变时，子帧间相关算法估计精度严重降低。 最后，为了适应高铁移动通信中大多普勒频偏的快速变化，解决高铁正负频偏跳变的问题，本文在子帧间相关算法的基础上，提出一种改进的频偏估计方法，即先采用基于单导频的频偏估计算法捕捉频偏范围，得到用于预校正的频偏初值后，再利用子帧间相关算法来锁定频偏值。获得频偏估计值后进行符号间频偏补偿和符号内频偏补偿。仿真结果表明改进算法估计精度高，能够实时跟踪校正频偏，极大地改善了LTE系统的整体性能，使系统具有误码率低，吞吐量大等优点。

Currently, the speed of high-speed railway generally have reached 250km/h, and some even have exceeded 350km/h. The accelerated pace of the speed of high-speed railway brings a range of effects to high-speed railway communication system, and the most influential factor is Doppler effect. If measures are not taken to restrain Doppler, system performance will be very poor. So it is very important to research on the frequency offset estimation and compensation algorithm of LTE system in high-speed railway scene. The paper mainly does the following works: Firstly, based on the transmission characteristics of wireless channel and the characteristics of high-speed railway environment, the high-speed railway channel model is studied and the simulation platform of LTE system is built. Secondly, a comparison of data-aided frequency offset algorithm and non-data-aided frequency offset algorithm is made in the paper. Since the data-aided algorithm based on pilot has the advantages of fast acquisition and high precision, the paper makes a further research on two kinds of the algorithm, sub-frame non correlation algorithm and sub-frame correlation algorithm. The results show that the frequency offset estimation range of sub-frame correlation algorithm is larger, so it is more suitable for high-speed environment. However, when the high-speed railway communication link quality is poor, the frequency offset will be too large and too hard to track and correct in real time by sub-frame correlation algorithm. Especially, when Doppler frequency offset changes between the biggest positive value and the biggest negative value, the estimation accuracy will be seriously reduced. Finally, in order to adapt to rapid change of large Doppler frequency offset and solve the frequency hopping problem, an improved frequency offset estimation method based on the sub-frame correlation algorithm is proposed. Using frequency offset estimation algorithm based on single pilot to capture the range of initial value of frequency offset for pre-correction, and determining the frequency offset value by sub-frame correlation algorithm. According to the estimated frequency offset value to compensate between inter-symbol and intra-symbol. The simulation results show that the algorithm has high estimation precision and can track and correct the change of frequency offset in real time, which greatly improves the overall performance of LTE system and makes LTE has the advantages of lower error rate and larger throughput.