说明：  OFDM信道估计仿真，运行时需要手动输入其循环前缀长度、最大多径时延扩展、最大多径时延扩展系数和信噪比
(Simulation of OFDM channel estimation, the need to manually enter the cyclic prefix length, maximum multipath time delay, the maximum multipath delay spread coefficient and signal-to-noise ratio operation)