摘要
传统的DFT信道估计算法性能比LS算法好,且复杂度也较低,但是这种算法经存在着三点问题:基于导频的DFT变换域的信道估计算法只有当多径信道的时延扩展为采样间隔的整数倍时,才能提高所估计信道响应的准确性。其次,DFT具有隐含周期性,如果原始数据序列首尾两端不连续,直接进行DFT必然会产生额外的高阶分量。最后,DFT信道估计只去除循环前缀以外的噪声,对循环前缀内部的噪声并没有进行任何抑制。针对这些问题,本文提到了一种加窗型DCT信道估计算法,并且在算法中在DCT逆变换之前设置门限阈值,进行对循环前缀的噪声进行去噪。最后的仿真结果很好地解决了DFT信道估计的不足。
Traditional DFT-based channel estimator for OFDM systems has better performance than LS channel estimators, and it also has low computational complexity.But three fanlts.First, it can increase the accuracy of estimates channel response only when all the paths of the delay are integer times as sampling interval.Second, DFT has the quality of implicit periodic.If the beginning and the end of the sequence of the original data are discontinuous, DFT transform will make it generate additional higher-order weight.The last, the traditional DFT-based channel estimator removes only the noise in the channel impulse response （CIR） beyond the length of the cyclic prefix （CP） , while the noise within the length of CP is not suppressed at all.Based on analysis of channel estimation algorithm using traditional DFT transform domain, new channel estimation is proposed based on windowed DCT transform Windowed.By introducing a decision threshold into the length of CP, the influence of the noise could be further removed by threshold processing.Simulation results show that the improved algorithm is superior to the original algorithm.
出处
《电子世界》
2011年第12期38-39,45,共3页
Electronics World
