APSK信号的混合盲均衡方法

针对幅度相移键控(amplitude phase shift keying,APSK)信号,为在载波相位恢复之前进行均衡,以减小码间干扰(inter-symbol interference,ISI)对载波恢复的影响,提出一种将恒模算法(constant modulus algorithm,CMA)和半径指导的均衡(radius directed equalization,RDE)方法相结合的盲均衡算法,该算法的代价函数是CMA代价函数和RDE代价函数的加权和。利用径向分散度的概念,该算法可以根据当前均衡程度自动地调整两种代价函数的权重,实现从CMA到RDE的软切换,从而自动适应不同均衡阶段和不同信噪比的情况。与单纯CMA均衡相比,该算法的收敛速度更快,而且稳态性能也更好,仿真结果验证了该方法的有效性。

Hybrid blind equalizing method for APSK signals

In order to equalize amplitude phase shift keying (APSK) signals before carrier phase recovery, sequentially mitigate the harmful effect of inter-symbol interference (ISI) on carrier synchronization, a hybrid blind equalizing method is proposed combining constant modulus algorithm (CMA) and radius directed equalization (RDE). The cost function of this algorithm is a weighted sum of CMA''s cost function and RDE''s. Using the concept of radial dispersion degree, this algorithm can automatically adjust the weights of the two cost functions, realizing a kind of soft switching from CMA to RDE, thereby adapts itself to different equalization phases or different signal to noise ratios (SNR). Compared with sole CMA equalization, the proposed algorithm can achieve faster convergence as well as better steady-state performance. Simulation results confirm the effectiveness of the proposed method.