Modified constant modulus algorithm based on new soft decision-directed scheme for both square-QAM system and cross-QAM system

In this paper, an improved constant modulus equalization algorithm called MCMA+MSDD is proposed based on CMA+SDD. The proposed CMA introduces variable step-size and modifies SDD method by dividing rectangular decision region S_xy dynamically. The MCMA+MSDD algorithm can be used not only in square-QAM system but also in cross-QAM system. The simulation results show that the proposed algorithm has better performance both in convergence speed and steady-state mean square error compared with the CMA+SDD and CMA+DD algorithm.