说明：  瑞利衰落信道（Rayleigh fading channel）是一种无线电信号传播环境的统计模型。这种模型假设信号通过无线信道之后，其信号幅度是随机的，即“衰落”，并且其包络服从瑞利分布。
(Rayleigh fading channel (Rayleigh fading channel) is a radio signal propagation environment, the statistical model. The model assumed that after the signal through the wireless channel, the signal amplitude is random, that is, " fading" and subject to its Rayleigh distribution envelope.)