说明：  在理想信道条件下、在高斯白噪声信道条件下和在先经过瑞利衰落信道再通过AWGN信道条件下的QPSK仿真（基带输入波形及其功率谱、QPSK调制信号及其功率谱、QPSK信号星座图、误码性能等）
(In an ideal channel conditions, in white Gaussian noise channel conditions and earlier through Rayleigh fading channels through QPSK simulation AWGN channel conditions (baseband input waveform and its power spectrum, QPSK modulation signal and its power spectrum, QPSK signal constellation Figure, error performance, etc.))