中文说明：
瑞利信道中，对于OFDM：
(1) 请设计一种具体的导引辅助的信道估计方法，用Simulink进行仿真。画出比特信噪比与信道估计均方误差的关系曲线和比特信噪比与误码率的关系曲线。
(2) 设频率已同步，请设计OFDM一种具体的采用循环前缀进行时间同步方法，用Simulink进行仿真，画出比特信噪比与捕获概率的关系曲线。
(3) 设时间已同步，请设计OFDM一种具体的采用循环前缀进行频率同步方法，用Simulink进行仿真，画出比特信噪比与频率同步误差的关系曲线。
English Description：
Rayleigh channel, for OFDM: (1) _, please design a specific guidance aided channel estimation method, using Simulink simulation.Draw a bit signal-to-noise ratio and the curve of channel estimation mean square error (mse) and bit SNR and bit error rate curve.(2) _ has a frequency synchronization, OFDM, please design a specific method of using cyclic prefix to time synchronization, using Simulink simulation, draw a bit SNR and the relationship between capture probability curve.(3) _ time has been synchronization, OFDM, please design a specific frequency synchronization method using cyclic prefix, using Simulink simulation, draw a bit signal-to-noise ratio and the curve of frequency synchronization error.