面向数据分组传输的OFDM时频同步系统研究

【作者】 毛勇；

【导师】 谢仁宏；

【作者基本信息】 南京理工大学 ， 通信与信息系统， 2004， 硕士

【摘要】 本文研究OFDM分组传输系统的符号同步与频偏估计算法。在分析信道特性和总结已有算法的基础上，对一种基于前导的定时同步算法在多径信道下出现较大定时误判的缺点做了改进。同时针对利用循环前缀的非数据辅助类估计算法在多径信道下定时估计不准确、频偏估计范围受限的缺点，提出使用改进型循环前缀相关估计来获得更准确的粗定时估计；利用OFDM分组传输系统载波结构上的特点进行整数频偏估计；利用有限的导频信号进行信道延迟估计从而获得准确的符号同步。结合几点改进提出了一种面向分组传输的无前导时频同步体系，并给出了信道估计算法以及载波和抽样频率的跟踪算法。随后使用MATLAB仿真验证了算法性能并提出了进一步研究的方向。这种同步方案适合于分组传输中的快速同步，具有复杂度低，数据利用率高的优点。更多还原

【Abstract】 This paper investigated the timing and frequency offset estimation algorithm of OFDM burst transmission systems. An improvement to Minn’s preamble based synchronization method is proposed to overcome the severe timing error in multipath environments. A new frame and frequency synchronization scheme without using preamble is presented for burst transmission. Based on modified OFDM cyclic prefix, the new method can achieve a more reliable coarse timing. The integer frequency offset, which cannot be acquired in cyclic prefix based algorithm, is achieved through post-FFT virtual sub-carriers. Channel delay estimation via pilot sub-carriers is used to provide accurate frame synchronization in multipath channels. Besides, the channel estimation method, carrier frequency and sampling clock offset tracking algorithms are also discussed in this paper. It is demonstrated through simulation that this scheme can provide a robust synchronization for OFDM burst transmission systems in Reyleigh fading channel with low complexity and high data rate. Finally the further research direction is suggested.更多还原