这部分代码实现了用ofdm的方法对于发送端进行调制的过程，其中包括了对于结果时域和频域的分析以及升采样后的波形。其中所用的载波数是12个。-This part of the code to achieve the OFDM method of transmitting side for modulating the process, including the analysis of the results of the time domain and frequency domain, as