OFDM盲载波间干扰抑制与同步算法研究

Research on Blind Inter-Carrier Interference Cancellation and Synchronization Method in OFDM Systems

针对载波频偏引起的子载波间干扰问题,提出一种基于独立分量分析的OFDM(orthogonal frequency division multiplexing)载波频率同步算法。本算法直接实现载波频率同步,可以避免基于导频机制的频偏估计和由频偏估计误差带来的频谱效率降低与性能损失。首先建立含频偏OFDM独立分量分析模型,然后从最大似然原则得到分离的代价函数,结合自然梯度优化得到OFDM源信号实现载波频率同步。理论分析表明,提出的算法不仅具有基于最大似然的频偏补偿性能而且提高了系统的输出信噪比。最后,仿真分析证明了算法的有效性。

With regard to the inter-carrier interference（ ICI） problem of（ OFDM） systems due to the carrier frequency offset（ CFO）,Independent component analysis（ ICA） based carrier frequency synchronization method is proposed. This algorithm achieves carrier synchronization directly. The CFO estimation based on pilot sequence and the performance loss due to imperfect CFO estimation can be avoided. In this paper,we first build an analogous ICA model for OFDM systems with the CFO. Then the cost function is obtained from the maximum likelihood（ ML） principle. Next,the source symbol recovery is acquired by nature gradient for the purpose of carrier frequency synchronization. Theoretical analysis shows that the ICA-based carrier frequency synchronization method not only has maximum likelihood（ ML） based CFO compensation source recovery ability,but also can improve signal to noise ratio（ SNR） of OFDM systems. At last,simulation analysis verifies the effectiveness of the proposed algorithm.