说明：  SM系统matlab程序，传输天线、接收天线数量可调，信号调制方式可调，循环次数可调。最后生成BER性能曲线，并将不同SNR下的BER数据存储到mat文件中。
(SM system matlab program, the number of transmission antennas, a receiving antenna is adjustable, adjustable signal modulation scheme, the number of cycles is adjustable. Last generate BER performance curve, and store data in different SNR BER under the mat file.)