3. 瑞利信道中的调制解调、信道估计：
(1)　　请推导出单径瑞利信道中的BPSK相干解调的理论误码率性能，并画出比特信噪比与误码率的关系曲线。
(2)　　在单径瑞利信道中，请设计一种时分的导引辅助的信道估计方法，用Simulink进行仿真，测量BPSK的误码率性能，画出比特信噪比与误码率的关系曲线，并与理论误码率曲线进行对比。(3. Modulation demodulation and channel estimation in Rayleigh channel:
(1) deduce the theoretical bit error rate performance of BPSK coherent demodulation in single-path Rayleigh channel, and draw the relationship curve between bit signal-to-noise ratio and bit error rate.
(2) in single-path Rayleigh channel, please design a time-division guidance assisted channel estimation method, Simulink simulation, measure the bit error rate performance of BPSK, draw the relationship curve between bit SNR and bit error rate, and compare with the theoretical bit error rate curve.)