Hybrid blind equalizing method for APSK signals
XU Fen · Journal of Chongqing University of Posts and Telecommunications · 2013
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.