QPSK在加性高斯白噪声环境下，信噪比和误码率的仿真。

先产生一个四组符号的序列，再将该序列映射到对应的相位上。用相应的函数产生均值为零、方差为δ2的加性高斯噪声。

-QPSK the additive white Gaussian noise environment, and the signal-to-noise ratio of the simulation. First group have a four symbols of sequence, then this sequence mapped to the corresponding phase on. With the corresponding function have zero mean and variance of 未2 additive white Gaussian noise.