说明：  一个基于空时分组编码的MIMO_OFDM通信系统的仿真设计。此系统包括QPSK调制解调，IFFT调制，空时编解码，基于训 练符号的信道估计等通信模块。
(A space-time block coding based on the MIMO_OFDM communication system simulation design. This system consists of QPSK modulation and demodulation, IFFT modulation, space-time coding and decoding, based on training symbols such as communication channel estimation module.)