8. 单径瑞利信道中的四发四收V-BLAST：
(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16QAM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)　　计算所设计方案的频谱效率是多少，单位为bit/Hz/s。(8. Four transmit four receive v-blast in single-path Rayleigh channel:
(1) please design a specific navigation-assisted channel estimation method and conduct simulation with Simulink to measure the bit error rate performance of 16QAM modulation.The relation curve between the bit signal-noise ratio and the mean square error of channel estimation is drawn, and the relation curve between the bit signal-noise ratio and the bit error rate is drawn.
(2) calculate the spectral efficiency of the designed scheme in bit/Hz/s.)