estimate the BER of BPSK over 1x2 Rayleigh channel as a function of the correlation between the channels.

产生QPSK信号，根据仿真的数据估计差错概率-Produce QPSK signal and estimate the data according to the error probability

本程序给出了OFDM信道的仿真，直接运行主函数OFDM_test即可，给出了信道BER随SNR的关系。-This procedure gives a simulation of OFDM channel and run directly the main function OFDM_test can, given the relationship between the channel BER with SNR.