说明：  6. 在三条径的瑞利信道中，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，测量BPSK调制时的误码率性能。画出比特信噪比与信道估计均方误差的关系曲线，画出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。
(。 6 In the three path Rayleigh channel for OFDM: (1) Please design a specific guide-assisted channel estimation method, the Simulink simulation, BPSK modulation measuring the bit error rate performance. Draw-bit signal to noise ratio and channel estimation mean square error curve, draw-bit signal to noise ratio and bit error rate curve. (2) set the frequency has been synchronized, the design of a specific OFDM cyclic prefix used for time synchronization method, the Simulink simulation, draw-bit signal to noise ratio and capture probability curve. (3) set time has been synchronized, the design of a specific OFDM cyclic prefix used for frequency synchronization method, the Simulink simulation, draw-bit signal to noise ratio and frequency synchronization error curves.)