In this paper

a Scaled Max-Log-MAP(SMLM) iterative equalization algorithm is proposed

and its sensitivity to SNR mismatch is also studied.The results show that SMLM algorithm performs much better than MLM

in addition to insensitivity to SNR errors

especially over low-loss channels.Then taking account of the possible hard-ckcision errors after first a few iterations using MLM algorithm

an improved switching turbo equalization algorithm between MLM and IM is presented

by which the performanse is improved dramatically compared to that without SNR correction.Finally

based on the fact of insensitivity of SMLM algorithm to SNR mismatch

a new switching equalization algorithm between SMLM and LM is also given.The simulation results show that this new algorithm can further not only improve the system performance

but reduce the complexity of systems

although it does not need any pilot symbols as well.