实现16QAM完整的调制解调系统，包括基带信号串并转换，星座图映射，升抽样成形滤波，升采样半带滤波，数字上变频，功放的多项式非线性效应，加性高斯白噪声信道，接收端下变频，降采样，匹配滤波，绘制接收端星座图。-16QAM modulation and demodulation realize the complete system, including the baseband signal string and conversion, constellation mapping, samplin