适用于高阶QAM信号的分数间隔混合盲均衡算法

A Hybrid Blind Equalization Algorithm Based on Fractionally Spaced Sampling for High-order QAM Signals

为了提高高阶QAM信号的盲均衡性能,提出一种分数间隔混合盲均衡算法。该算法将恒模盲均衡算法(CMA)与判决引导算法相结合,并充分利用了分数间隔均衡结构在收敛速度、稳态误差方面的优势。均衡器系数更新首先进行时域解相关,为了消除恒模盲均衡算法的相位不敏感特性,在实现上构造载波同步与盲均衡的大环路。仿真结果表明,对方形星座图的高阶QAM信号,该算法可以提供更快的收敛速度和更小的稳态误差。

For improving the equalization performance of high-order QAM signals,a hybrid blind equalization algorithm based onfractionally spaced sampling is proposed. The algorithm is proposed by joining the Constant Modulus Algorithm （ CMA） with the decision directed algorithm. It takes full advantage of the fractional interval structure,providing faster convergence speed and better steady state performance. Decorrelation in time domain is employed for input signals firstly, and then the signals can be used for updating the coefficients of the equalizer. The CMA algorithm has little correlation of phase, so a loop which realizes carrier synchronization and equalization simultaneity is presented. Simulation results demonstrate that the proposed algorithm provides superior performance by increasing the convergence rate and decreasing the steady-state mean square error for square-shape high-order QAM signals of square QAM constellation.