适用于高阶QAM信号的水声信道修正盲均衡算法

针对水声信道的相位旋转问题，提出了适用于高阶QAM(quadrature amplitude modulation)信号的改进的修正常数模算法（improved modified constant modulus algorithm, IMCMA）。在不增大计算量的前提下，对修正常数模算法（MCMA）的权值迭代函数进行修改，从而修正误差控制函数，改善相位补偿能力。在具有多普勒相位旋转的典型两径水声信道环境中进行计算机仿真。结果表明，IMCMA算法相比MCMA算法加快了收敛速度，改善了稳态误差性能；同时又具有和LMS(least mean square)算法相当的相位补偿能力和收敛性能。IMCMA算法可为高速水声通信提供一种非常实用的均衡方法。

Improved blind equalization algorithm suitable for high-order QAM signals used in underwater acoustic channels

An improved blind equalization algorithm(Improved MCMA)suitable for high-order QAM signals is proposed, in order to overcome the problem of the phase rotation in underwater acoustic communication system. Weight iterative function of modified constant modulus algorithm(MCMA)is modified on the premise of not increasing computational quantity, accordingly, error control function is modified and phase compensation ability is increased. The computer simulations of new algorithm about convergence and carrier recovery ability are carried out under typical two-path underwater acoustic channel with dopple frequency shift.The simulation results demonstrate that the mean square error and convergence rate of the proposed algorithm have been improved to some extend compared with MCMA algorithm, and its phase compensation and convergence ability is close to least square error algorithm(LMS). The proposed algorithm may be a good practical equalization method in high-rate underwater acoustic communication.