【作者】 王伟伟；

【导师】 王静；

【作者基本信息】 大连海事大学 ， 通信与信息系统， 2006， 硕士

【摘要】 对于高速无线通信系统来说,正交频分复用(OFDM)是一种值得关注的调制技术,因为它具有较高的频谱利用率和良好的抗多径干扰能力。在OFDM系统中,整个系统的带宽被分成许多子载波,各个子载波相互正交使得系统的频谱利用率提高。而且,循环前缀的引入消除了符号间干扰(ISI),避免了信道间干扰(ICI)。 然而,OFDM的这些优点只有在各个子载波保持正交性时才能体现出来。如果这种正交性遭到破坏,ICI就会使系统的性能严重退化。而产生ISI和ICI的主要原因是在OFDM系统接收端产生的符号定时偏差和载波频率偏差。因此同步是OFDM系统研究的一个主要课题,意义重大。 目前,估计载波频率偏差和符号定时偏差的算法主要有数据辅助的方法和非数据辅助的方法以及基于循环前缀的算法。本文主要是研究、分析、比较使用上述方法估计载波频率偏差和符号定时偏差的一些算法。同时将这些算法进行Matlab仿真。通过仿真结果来验证算法的性能。本文旨在分析比较各种算法,找出各算法的优点,使物尽其用。更多还原

【Abstract】 OFDM (orthogonal frequency division multiplexing) is an appealing modulation technique for high-speed wireless communication system owing to its spectral efficiency and robustness against multipath fading. In the OFDM system, the whole system bandwidth is divided into many sub-channel with narrow bandwidth and bandwidth efficiency is increased by allowing overlapping of the sub-channels. Moreover, serious ISI (Inter-Symbol Interference) and ICI (Inter-Carrier Interference) can be readily circumvented by introducing CP (Cyclic Prefix) .However, these advantages of the OFDM systems can be only guaranteed when the orthogonality between sub-carrier is maintained. If this orthogonality is destroyed, serious deterioration of system performance may occur due to ICI between sub-carrier. The most critical causes yielding the ISI as well as ICI are symbol timing and carrier frequency offset which are occurred in the OFDM receiver. Hence, synchronization has been a major research topic in OFDM systems for they are sensitive to symbol timing error and carrier frequency offset.Various existing synchronization algorithm to estimate symbol timing offset and carrier frequency offset can be classified into blind and pilot-aided methods and algorithm based on cyclic prefix. This paper mainly studies, analysis and compares some synchronization algorithms using these methods. At the same time, simulations of this algorithms are taken by Matlab. The performance of each synchronization algorithm are shown by simulation result. The main purpose of this paper is to analysis and compare some existing synchronization algorithms and find out their advantage and their best application fields.更多还原