基于对称扩展DFT变换的OFDM系统信道估计方法

针对OFDM系统提出一种基于对称扩展DFT变换的信道估计方法.所提方法通过对初始最小二乘估计进行对称扩展DFT变换,并在变换域进行MMSE滤波以获得更为精准的信道估计.与传统DFT变换相比,对称扩展DFT变换可以降低信号边界上的不连续性,具有更好的能量集中特性和更低的频谱泄露.仿真结果及复杂度分析表明,所提方法可以在不明显增加计算复杂度的同时,有效改善实际OFDM系统中虚载波引起的频谱泄漏问题,提高边缘子载波信道估计的性能.与传统DFT变换信道估计方法相比,只需扩展较少的点数,即可获得2dB左右的性能增益,且随扩展点数的增加,所提方法的性能逐渐逼近DCT信道估计性能.

Symmetric extension DFT-based channel estimation for OFDM systems

A novel channel estimation method based on symmetric extension discrete Fourier transformation(DFT) for orthogonal frequency division multiplexing(OFDM) systems is proposed in this paper.More accurate channel estimation is achieved by the proposed method through calculating symmetric extension DFT of the least square(LS) estimation and then applying a minimum mean square error(MMSE) filter in the transform domain.The signal discontinuity problem in conventional DFT is alleviated through symmetric extension DFT,therefore a better power concentration and a lower spectrum leakage can be obtained.Simulation results and complexity analysis show that with an ignorable increase of computational complexity,the proposed method can effectively reduce the aliasing error caused by virtual subcarriers and significantly improve the performance of the channel estimation on the edge subcarriers.Compared with the conventional DFT based method,a performance gain around 2 dB is acquired by the proposed method when only a few points are extended symmetrically.And the performance of discrete cosine transformation(DCT) based channel estimation can be approached with the increasing of symmetric extension points.