说明：  衰落信道参数包括多径扩展和多普勒扩展。时不变的多径扩展相当于一个延时抽头滤波器，而多普勒扩展要注意多普勒功率谱密度，通常使用Jakes功率谱、高斯、均匀功率谱。
( The fading channel parameters include multipath spreading and Doppler spreading. The time-invariant multipath extension is equivalent to a delay-tap filter, while the Doppler spread should pay attention to Doppler power spectral density, usually using Jakes power spectrum, Gaussian, and uniform power spectrum.)