说明：  程序实现了OFDM通信系统的仿真，包括QPSK调制、串并转化、IFFT、并串转化、插入保护间隔AWGN信道传输以及逆过程
(The program realizes the simulation of OFDM communication system, including QPSK modulation, serial-parallel conversion, IFFT, parallel-serial conversion, insertion protection interval AWGN channel transmission and inverse process.)