基于快时变信道的LTE系统信道估计技术研究

发布时间：2018-04-11 09:40

本文选题：高速铁路 + 无线宽带接入　；参考：《西南交通大学》2014年硕士论文

【摘要】：近年来,我国的高铁事业发展得如火如荼,高铁时速的不断提升给高速铁路通信提出了更高的要求,配合当下第四代公众通信网络(4G)的普及,应用于高速铁路车地通信的高速无线宽带通信系统的研究成为当下的热点。在由列车高速运动导致的快时变信道条件下,准确的信道估计技术将变得更为重要,特别是以MIMO-OFDM为核心的LTE通信系统。本设计主要研究移动台高速移动环境下基于导频的信道估计技术。论文首先介绍了无线移动通信系统的信道特性以及信道的时间色散和频率色散参数,并介绍了基于这两种参数的快慢衰落和频率选择性衰落的划分依据。分析了高速铁路环境下移动通信系统面临的挑战和发展机遇,介绍了作为LTE核心技术的OFMD和MIMO技术的基本原理。接下来依据3GPP链路层协议的部分内容搭建了下行链路MIMO-OFDM系统,仿真验证了2发2收天线STBC-OFDM系统相比SISO-OFDM的性能提升。在此基础上研究了导频信号的序列与插入方式,实现了基于gold序列和Zadoff-Chou序列的导频图案性能对比。重点研究了当前主流的几种信道估计方法,包括LS、LMMSE以及SVD-LMMSE算法,并讨论了接收端SNR估计误差对信道估计性能的影响。研究了数据位置的插值算法,包括线性插值算法、二阶多项式插值算法和三次样条插值算法,并在此基础上进行了性能仿真,重点比较了在不同时延下的信道中,不同插值算法在一个LTE子帧中的误码性能。在快时变的信道估计中采用了BEM算法来进行时域信道拟合,首先介绍了常见的几种BEM算法,讨论并仿真了多普勒频移和BEM阶数对不同BEM算法信道拟合性能的影响。分析了在快时变信道下的子载波干扰的产生以及分簇导频的使用并在仿真中实现,在此基础上分析了基于BEM算法的信道估计原理,并给出了基于MIMO-OFDM系统的CE-BEM和DPS-BEM信道估计性能仿真分析。
[Abstract]:In recent years, the high-speed rail industry in our country has been developing in full swing, and the constant increase in the speed of high-speed rail has put forward higher requirements for high-speed railway communications, in line with the popularization of the current fourth-generation public communications network (4G).The research of high-speed wireless broadband communication system for high-speed railway vehicle-ground communication has become a hot spot.Under the condition of fast time-varying channel caused by the high speed movement of train, the accurate channel estimation technology will become more important, especially the LTE communication system with MIMO-OFDM as the core.This design mainly studies the channel estimation technology based on pilot in mobile station high speed mobile environment.This paper first introduces the channel characteristics of wireless mobile communication system and the time dispersion and frequency dispersion parameters of the channel, and introduces the dividing basis of fast and slow fading and frequency selective fading based on these two parameters.This paper analyzes the challenges and development opportunities of mobile communication system in high-speed railway environment, and introduces the basic principles of OFMD and MIMO technology, which are the core technologies of LTE.Then the downlink MIMO-OFDM system is built according to the part of the 3GPP link layer protocol. The simulation results show that the performance of the 2 transmit and 2 receive antenna STBC-OFDM system is better than that of the SISO-OFDM system.On this basis, the pilot signal sequence and insertion mode are studied, and the performance comparison of pilot pattern based on gold sequence and Zadoff-Chou sequence is realized.Several popular channel estimation methods, including LSS-LMMSE and SVD-LMMSE algorithm, are studied in detail, and the influence of receiver SNR estimation error on channel estimation performance is discussed.The interpolation algorithms of data location, including linear interpolation algorithm, second-order polynomial interpolation algorithm and cubic spline interpolation algorithm, are studied.Error performance of different interpolation algorithms in a LTE subframe.In the fast time-varying channel estimation, BEM algorithm is used for channel fitting in time domain. Firstly, several common BEM algorithms are introduced, and the effects of Doppler shift and BEM order on channel fitting performance of different BEM algorithms are discussed and simulated.The generation of subcarrier interference and the use of cluster pilots in fast time-varying channels are analyzed and implemented in simulation. Based on this, the principle of channel estimation based on BEM algorithm is analyzed.Simulation analysis of CE-BEM and DPS-BEM channel estimation performance based on MIMO-OFDM system is given.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN929.5

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