中文说明：本文讨论了QPSK在Rayleigh信道中的误码率性能，包括理论Rayleigh模型和AWGN（Additive White Gaussian Noise）下的误码率，并与仿真结果进行了比较。模拟信号通过瑞利信道进行调制并添加AWGN。然后对Rayleigh信道进行分频解调，并对误差进行统计，得到QPSK的误码率性能
English Description：
This code is about BER performance of QPSK in Rayleigh channel. It also contains theoretical Rayleigh model and also ber for AWGN(Additive White Gaussian Noise) and comparing with the simulated result. The simulated signal is modulated through the Rayleigh channel and added AWGN. Then demodulated by dividing Rayleigh channel and counted the error to get the BER performance for QPSK