OFDM系统中基于改进阈值的DFT信道估计算法

在正交频分复用(Orthogonal Frequency Division Multiplexing,OFDM)系统中,传统的离散傅里叶变换(Discrete Fourier Transform,DFT)信道估计算法对循环前缀之内的噪声没有得到抑制,只是抑制了循环前缀之外的噪声.以循环前缀之外的噪声点的能量值来设置阈值对于循环前缀之内噪声的滤除不是很理想,为此本文通过将循环前缀内外的样本点分别排序,分别选取其中一部分样本能量值的平均值,并乘以适当系数,以两部分和作为一种新的时域阈值来抑制噪声.仿真结果表明,本文改进的算法能很好地抑制循环前缀之内的噪声,保留了有效的信号,误码率和均方误差均比得到进一步的降低.

DFT Channel Estimation Algorithm Based on Improved Threshold in OFDM System

In the OFDM system, traditional DFT-based channel estimation algorithm can not suppress noise inside the cyclic prefix, which can only suppress noise outside the cyclic prefix. Setting the threshold of the noise points outside the cyclic prefix is not ideal for filtering the noise in the cyclic prefix. To solve the problem, this paper proposes a new threshold. It takes average energies of two middle part of the sample points,and then multiply the appropriate factors. Simulation results show that the improved algorithm can effectively suppress the noise in the cyclic prefix, and retain the effective signal. The bit error rate and mean square error can be further reduced .