多径回波信道条件下回波抵消技术研究

Study on Echo Cancellation Technology of Multipath Channel

主要研究移动通信数字同频直放站的回拨抵消技术。通过对基于最小均方误差原理的自适应滤波器的收敛条件进行分析,发现即使在外信道为单径信道或只考虑多径信道的主径回波信道时,现有利用时延去相关的自适应滤波算法,在原理上存在着不能保证满足收敛条件的问题。针对这一问题,本文提出了将发送信号进行延时后再送入自适应估计器的改进措施,有条件地改善了回波抵消效果,并进一步提出了消除多径回波的新型技术原理。

In this paper, we study the echo cancellation technology of the on-frequency digital repeater. By analyzing the convergence condition of adaptive filter based on least mean square （LMS） principle, we find that existing adaptive filtering algorithm using delay to eliminate the relevance is not able to guarantee the convergence condition being satisfied in principle, even when the outer channel is a single-path or a main path of mulfipath channel.We propose a novel algorithm sending the signal into the adaptive estimator after a delaying time to solve the problem. The novel algorithm conditionally improves the effect of echo cancellation. Further more, this oaoer oroooses three new orinciDles to eliminate the multiDath echo.