一种适用于高阶QAM信号的抗扰动水声信道盲均衡算法研究

Research on a robust blind equalization algorithm suitable for high order QAM signals used in underwater acoustic channels

水声信道存在有大量的脉冲噪声,这些噪声会对均衡算法的稳健性造成影响,严重时还会使算法崩溃。从提高均衡算法稳健性的角度出发,采用均衡滤波器系数变化量的Euclid范数作为代价函数,提出了一种双模式归一化修正常模盲均衡算法,并针对算法收敛速度慢的问题,利用判决正方形方法进行了改进。仿真、试验结果表明,在高阶QAM通信系统中,新的盲均衡算法在收敛能力、收敛速度以及稳健性方面都较传统的双模式MCMA/DD算法更有优势。

There are a lot of impulse noises in the underwater acoustic channels, which will not only deteriorate the robustness of equalization algorithm, but also destroy the algorithm if the level of impulse noises is strong. To improve the robustness of equalization algorithm, this paper presents a new normalized modified constant modulus algorithm operating under the ＂dual mode＂, which takes Euclid norm of changes in equalization filter as the cost function, and then introduces the square decision technique to achieve better convergence speed. The results of simulation show that this new equalization algorithm performs better than traditional MCMA/DD algorithm not only in the ability and speed of convergence, but also the robustness of algorithm in high order QAM communication systems.