Square contour decision-based super-exponential iteration blind equalization for QAM signals
Duan Li · Shengxue jishu · 2013
A modified super-exponential iteration decision feedback blind equalization algorithm based on square contour decision(SDMSEI-DFE-2DPLL) is proposed,in order to solve the problem about the ill convergence performance of super-exponential iteration decision feedback algorithm in underwater acoustic communication system.Firstly,based on modified super-exponential iteration algorithm,equalization of the in-phase and quadrature components of output signals are implemented by square contour decision to improve phase compensation ability.At the same time,a second order digital phase-locked loop is introduced in order to track and compensate phase rotation.Experiments are carried out by using 16QAM modulation signals in anechoic tank to verify the performance of algorithms in terms of bit error rate(BER) by comparing the influences caused by filter weight vector length,step size and Q matrix size.The results show that the BER of the proposed algorithm is better than that of the MSEI-DFE algorithm by two magnitudes,and the phase rotation can be compensated and the carrier recovery ability is improved very well.