基于DFT的OFDM无线通信系统信道估计算法研究

Research on channel estimation algorithm of OFDM wireless communication system based on DFT

在OFDM系统中,针对LS信道估计忽略噪声的问题,提出了一种基于DFT的信道估计改进算法。该算法在时域和频域上分别进行降噪处理,提高信道估计性能。在时域上,对信道冲击响应进行截断补零,减少带外噪声的影响,通过阈值加窗减少带内噪声的影响。在频域上,采用了相邻信道的联合估计,使得噪声能量降低3 dB。仿真结果表明,在高斯信道下,系统误码率为10^(-4)时,改进的DFT估计算法比传统DFT估计算法性能提高1.5 dB;在COST207乡村模型多径信道下,系统误码率为10^(-2)时,改进的DFT估计算法比传统DFT估计算法性能提高2 dB。

In OFDM systems,an improved channel estimation algorithm based on DFT is proposed to solve the problem of ignoring noise in LS channel estimation.The algorithm reduces noise in time domain and frequency domain respectively to improve the performance of channel estimation.In the time domain,the channel impulse response is truncated and zero⁃filled to reduce the influence of out⁃of⁃band noise,and the influence of in⁃band noise is reduced by thresholding and windowing.In the frequency domain,the joint estimation of adjacent channels is adopted to reduce the noise energy by 3 dB.Simulation results show that the performance of the improved DFT estimation algorithm is 1.5 dB better than that of the traditional DFT estimation algorithm when the system bit error rate is 10^(-4) in gaussian channel.In the COST207 rural model multipath channel,the performance of the improved DFT estimation algorithm is improved by 2 dB compared with the traditional DFT estimation algorithm when the system bit error rate is 10^(-2).