OFDM系统中一种新型盲载波频偏估计

摘要

The combination of orthogonal frequency division multiplexing ( OFDM) is known as an efficient technique to combat frequency selective channels. Significant performance degradation can result from carrier frequency offset , which caused Inter Carrier Interference (ICI). Based on the analysis of the effect of frequency offset, a new blind frequency offset estimation algorithm which associates with the decoder is proposed. This algorithm need only one OFDM symbol. The hard-decision information provided by BICM is regarded as virtual training sequence. Using of the correlation between the feedback signals and received signals, the frequency offset can be estimate. The precision will be improve by the feedback information that provided by iterative decoder of BICM. The simulation results show that , the proposed algorithm efficiently estimates frequency offset after three iterations.%正交频分复用(OFDM)是一种能够有效地抗频率选择性衰落的技术.由于载波频偏的存在会引起载波间干扰,导致系统性能的严重下降.在分析载波频偏对系统影响的基础上,提出了一种联合译码的新型盲频偏估计算法.该算法只需要一个OFDM符号,将BICM译码的硬判决反馈信息作为虚拟训练序列,利用该反馈信号与接收信号的相关性进行频偏估计.通过BICM迭代译码,更新译码反馈信息,提高频偏估计精度.仿真结果表明,提出的算法经过3次迭代,可以有效地进行频偏估计.