I also found something wrong with the multipath channel module in simulink. I seth the number of path to be 1, but failed to achieve the theoretical BER of BPSK. I used the simple BPSK modulation. I have to do the work by using matlab where the multipath fading channel is written by us. I hope to trans. my matlab .m files to be simulink module, but I did not know how to use .m file to do this. Anybody can give a hand. Thanks in advance.