Although the dual mode blind equalization algorithm based on constant modulus and decision directed (DD) criterion can significantly improve the performance of equalization

the dual mode blind equalization algorithms at present need to set up the switching parameters which lack of theoretical basis.To solve the problem that the switching parameters are difficult to be determined in the dual mode blind equalization algorithm

a new dual mode blind equalization algorithm with combination cost function is proposed.The combination cost function is obtained by using the weighted constant modulus and DD cost function

and the weight is adaptively adjusted during the blind equalizer update process to switch from constant modulus algorithm (CMA) to DD algorithm

which avoids the design of the switching parameters in the dual mode algorithm

and the generalization performance can be improved.To overcome the shortcoming of phase blindness of CMA

the proposed algorithm is optimized based on modified CMA (MCMA)

which can further improve the convergence performance.The simulation results show that the proposed dual mode blind equalization algorithm can take full advantages of CMA and DD algorithm

which has faster convergence rate and lower steady state error.