基于DFT的短波OFDM系统信道估计改进算法

Improved Channel Estimation Algorithm Based on DFT for Shortwave OFDM System

传统的DFT算法利用信道估计冲击响应的长度小于循环前缀长度的原理,滤除了循环前缀码长度以外的噪声,循环前缀内的估计值仍存在噪声,结合传统DFT信道估计算法,提出了一种短波OFDM系统的基于DFT的改进信道估计算法,此算法首先进行传统的DFT信道估计算法,滤除部分噪声信号。再根据信道脉冲响应的幅值选取幅值最大的Ng/2个信号作为有用信号,然后用DFT得到的估计值的平均值替换其余Ng/2个信号,最后得到基于DFT改进算法的信道估计信号。仿真结果表明该算法性能有很大提高。

Utilizing the theory that the length of impulse response is shorter than that of cyclic prefix,the conventional DFT channel estimation algorithm filters out the noises out of the cyclic prefix length.However,the estimated value still has noises within the cyclic prefix.Combining with the conventional DFT channel estimation algorithm,an improved DFT channel estimation algorithm is proposed for shortwave OFDM system.The algorithm uses the conventional DFT channel estimation algorithm to filter out part of the noises,and then selects the largest channel impulse response signal as useful signal according to the magnitude of the amplitude. It then uses the average value of the estimated values to replace the remaining signals,and finally obtains a signal based on the improved DFT estimated channel algorithm.The simulation results show that the channel estimation performance of this algorithm is greatly improved.