基于前向平均和时域滤波的OFDM信道估计算法

A Channel Estimation Method for OFDM Based on Forward Averaging and Time Domain Filtering

为减少系统中噪声对信道估计的影响，提出了一种基于抑制噪声的信道估计方法。首先对几个连续OFDM信号相同导频位置的信道频率响应前向平均后线性插值，得到所有子载波的信道估计值；然后在时域利用滑行相关系数估计出的时延进行时域滤波。该方法通过在频域和时域的两次减噪，提高了信道估计的精确性，尤其是所提出的前向平均法适用于快衰落信道。仿真结果表明，该方法可将OFDM系统的误码率性能提高4～5dB。

In order to reduce the impact of system noise on the channel estimation, a new method based on noise suppression is presented. Firstly, the channel frequency response is averaged at the same pilot positions in several OFDM symbols, then all the channel coefficients are obtained by linear interpolation. Secondly, maximum delay spread is estimated from the sliding correlation coefficients for time domain filtering. After the two processes of noise reduction, the estimate accuracy is improved , especially the forward averaging method is suitable to the fast - fading channel environment. Simulation results demonstrate that the proposed approach improves the BER performance by 4- 5dB after equalization.