Rician衰落通道用于对视线（LOS）进行建模，其中因子K被定义为LOS的平均功率与非视线（NLOS）的平均功率的比值。 修改b）中的代码，分别实现K = -40 dB和15 dB的Rician衰落。(A Rician fading channel is used to model the channel with line of sight (LOS), where a factor K is defined as the ratio of the mean power of the LOS to the mean power of the non-line of sight (NLOS). Modify the code in b) to implement Rician fading with K=-40 dB and 15 dB, respectively.)