一种新的变步长盲恒模信道均衡算法

A New Variable Step Size CMA Algorithm for Blind Channel Equalization

无线数字通信中,由于电磁干扰和多径效应的影响,使通信质量下降,进而产生码间干扰(inter-symbol interference,ISI),ISI的存在会大大降低系统性能,影响码速率的提高。信道均衡技术是解决该问题的一种重要手段,但剩余误差偏大。以信道盲均衡算法中的恒模(CMA)算法为研究背景,提出了一种新的变步长CMA算法,新算法利用QAM信号分布于几个已知圆上的特点,根据均衡器输出信号的模估计理想输出的模。计算机仿真结果表明这种算法能有效地减小剩余误差,是一种很实用的信道均衡算法。

In wireless digital communications, the communication quality drops and brings the inter-symbol interference （ISI） because of the multi- path transmission of electromagnetic waves and electromagnetic interference. The existence of ISI may dramatically degrade the performance of wireless communication system and block the raise of communications rate. A channel equalization technology is an important instrument to solve the problem, but its residual error is big. An arithmetic based on a blind channel equalization is proposed. It utilizes the characteristic of QAM signal distributing on several foregone circularities. The arithmetic estimates ideal modulus based on the oatput＇s modulus of the equalizer. Computer simulation results show that the new algorithm can efficiently reduce residual errors by adaptively changing step sizes and is a practical algorithm.