一种适用于高阶QAM信号的双模式多模盲均衡算法

Dual-mode Multi-modulus Blind Equalization Algorithm for High-order QAM Signals

为了克服常数模算法(CMA)收敛速度慢、稳态误差大的缺点,利用QAM信号信道利用率高及高阶QAM信号模值不为常数的特点,提出了一种适用于高阶QAM信号的双模式多模盲均衡算法(DMMA)。该算法以常规的CMA为基础模式,以多模算法(MMA)为第二模式,用该模式对于处在不同模值上的信号,以相对应的模值为参数分别进行均衡。另外,两种模式是同时对信号进行均衡的,并且在第二模式中,利用判决条件对均衡器的输出信号进行判决,使得模值能自动进行切换。利用水声信道对DMMA和CMA进行仿真实验,结果表明,与CMA相比,DMMA能针对性地对位于不同模值上的信号分别进行均衡,且收敛速度快、稳态误差小。

In order to overcome the slow convergence rate and large state error of the CMA, based on the high utilization efficiency of QAM signal to the limited bandwidth channel and the feature of high-order QAM signals with different modulus, a Dual-Mode Multi-modulus blind equalization Algorithm （DMMA） for high-order QAM signals was proposed. This proposed algorithm used the CMA as the first mode whereas it employed the Multi-Modulus Algorithm （MMA） as the second mode, which could equalize for the higher order QAM signals with the different modulus. Furthermore, in the DMMA, the two modes operated concurrently, and in second mode, based on the decision of the equalizer＇s output, the iteration process of the MMA alternated automatically among different modulus. The efficiency of the DMMA was proved by computer simulations in underwater acoustic channels.