This paper focuses on the influence of soft decision decoding on multilevel coding (MLC) schemes with different mapping strategies over Rayleigh fading channels.Based on Capacity Rule

8ASK MLC systems are constructed using punctured convolutional codes.The formulations for computing the soft decision metrics with Channel State Information (CSI) are presented for multistage decoding (MSD) and the performance comparisons are made for soft- and hard-decision.The error propagation resulted from the lower level is also discussed.The results can present some references for the optimal design of MLC in fading channels.