说明：  程序仿真了瑞利信道，分析和大量实测表明，多径效应使接收信号包络变化接近瑞利分布。在典型移动通信中，衰落深度达30dB左右，衰落速率约30~40次/秒。
(Rayleigh channel simulation procedures, analysis and extensive test shows that the received signal multipath effect changes in the envelope close to the Rayleigh distribution. In a typical mobile communication, fading depth of about 30dB, the decline rate of about 30 to 40 times/sec.)