【作者】 张京梅；

【导师】 刘岚；

【作者基本信息】 武汉理工大学 ， 通信与信息系统， 2008， 硕士

【摘要】 随着无线移动通信的发展,人们对于无线通信系统的传输速率和系统容量提出了越来越高的要求;然而有限的频谱资源成为制约移动通信发展的瓶颈,因此在保证可靠传输的前提下,如何提高频谱效率成为当今无线通信领域研究的重点课题;在此领域,OFDM技术和MIMO技术引起了专家学者的广泛关注;多天线发送多天线接收(MIMO)和正交频分复用(OFDM)两种技术的结合被认为是未来无线宽带通信最有效的传输技术之一,既可以很好的解决未来宽带无线通信系统中信道的多径衰落和带宽效率这两个最严峻的挑战,又能够提高系统容量和传输可靠性,所以MIMO-OFDM成为4G核心技术首选方案,而定时同步和频率同步是影响MIMO-OFDM系统性能的关键因素。本论文对SISO/MIMO-OFDM系统定时同步和频率同步作了深入且较全面的研究,主要工作如下:1)分析了SISO-OFDM系统基本原理,推导了SISO-OFDM系统定时同步和频率同步偏差。2)详细研究了SISO-OFDM系统基于训练序列和基于循环前缀的定时同步典型算法,并提出基于循环前缀的改进算法,还指出了各种算法的优缺点,通过实验仿真说明了各种算法的性能。3)研究了SISO-OFDM系统基于训练序列、基于循环前缀和基于频域导频的几种频率同步算法,并进行了仿真实验和性能分析。4)给出了MIMO-OFDM系统结构和信号模型,分析了MIMO-OFDM系统同步误差模型和前导结构,对几种典型的MIMO-OFDM系统的前导结构进行了详细的讨论。5)提出了一种基于IEEE 802.11a的MIMO-OFDM前导结构和基于相关的优化同步方案,对这种同步方案进行了详细的介绍,并进行了性能仿真。更多还原

【Abstract】 With the development of wireless mobile communications,People made ever-increasing demands for the transfer rate and system capacity of wireless communications system,However,the limited spectrum resource constraints become a bottleneck in the development of mobile communications,Therefore,to ensure the premise of reliable transmission,how to improve spectrum efficiency in the field of wireless communications become the focus of the study subjects.In this area,OFDM technology and MIMO technology has aroused extensive attention from experts and scholars.The combination of MIMO and OFDM techniques is regarded as one of the best transmission method in the future wireless broadband communication.It not only solves the problems of multi-path fading channel and bandwidth efficiency well,but also enlarges the system capacity and achieves highly reliable transmission.Therefore, MIMO-OFDM has become the first choice of core program in 4G technology, however,timing synchronization and frequency synchronization are the key effects which influence the performance of OFDM system.This paper introduces the synchronization algorithms in SISO/MIMO-OFDM systems thoroughly and comprehensively,the main contents of the dissertation are expressed as follows:Firstly,the basic theory of SISO-OFDM system is introduced,and the errors of timing synchronization and frequency synchronization are deducted.Secondly,the typical timing synchronization algorithms based on training sequence and cyclic prefix are detailed and compared,some improved algorithms based on cyclic prefix are also presented,simulations results illustrate the performance of algorithms.Thirdly,the frequency synchronization algorithms based on training sequence, cyclic prefix and pilots in frequency domain are detailed,some simulation results illustrate the performance of algorithms.Fourthly,MIMO-OFDM system structure and signal model are introduced, synchronization error model and preamble configuration are discussed.Several typical synchronization schemes in MIMO-OFDM systems are detailed.Finally,a new MIMO-OFDM preamble configuration based on IEEE 802.11a and an optimized synchronization schemes based on correlation are presented,some simulation resulted are also presented.更多还原