对有3条固定路径的AWGN多径信道中的QPSK系统进行BER性能仿真，并与在理想的AWGN信道（没有多径）中同样系统地BER性能进行比较-to have three fixed path over the AWGN Channel QPSK BER performance system simulation, and with the ideal AWGN channel (multi-path) to the same system BER performance comparison