OFDM中基于DFT信道估计的改进算法

在正交频分复用(OFDM)系统的估计算法中,基于离散傅里叶变换(DFT)的信道估计因其算法实现简单,性能又优于最小二乘法(LS),常常用于实际OFDM系统中.传统的DFT算法中通常只抑制了信号中循环前缀(CP)外的噪声,并没有消除循环前缀内的噪声.提出了一种改进型算法,该算法通过加窗降低系统中频谱泄露现象,并对噪声进行估计修正,考虑到CP范围内外的噪声分布情况,设置了一个新的阈值点来抑制样本内的噪声.仿真结果表明:该算法较传统的DFT估计算法性能更好,更进一步地改善了系统误码率,能获取准确的信道信息.

An Improved Algorithm Based on DFT Channel Estimation in OFDM

In the estimation algorithm of orthogonal frequency division multiplexing (OFDM) system,the channel estimation based on discrete Fourier transform (DFT) is often used in practical OFDM system due to its simple algorithm,and performance is better than the Least Squares (LS).The traditional DFT algorithm usually only suppresses noise outside the cyclic prefix (CP) in the signal,and does not eliminate noise inside the cyclic prefix.An improved algorithm is proposed in this paper,which firstly reduces the frequency spectrum leakage in the system through windowing and estimates and corrects the noise.Secondly,considering the noise distribution inside and outside of the CP range it suppresses the noise in the sample by setting a new threshold.The simulation results show that the proposed algorithm performs better than the traditional DFT estimation algorithm and can further improve the system BER and obtain accurate channel information.