说明：  在三条径的瑞利信道中，对于直接序列扩频： (1)设计DS-CDMA一种具体的码分导引辅助的信道估计方法，接收机分别采用等均益合并、最大比合并。 (2)设频率已经同步，设计DS-CDMA一种具体的单停顿滑动相关时间同步方法。 (3)设时间已经同步，设计DS-CDMA一种具体的频率同步方法，画出比特信噪比与频率同步误差的关系曲线。
(In the three path Rayleigh channel, for direct sequence spread spectrum: (1) A specific channel estimation method aided by code division and guidance is designed for DS-CDMA. The receiver adopts equal average combining and maximum ratio combining respectively. (2) Assuming that the frequency has been synchronized, a specific single pause sliding correlation time synchronization method for DS-CDMA is designed. (3) Assuming that time has been synchronized, a specific frequency synchronization method of DS-CDMA is designed, and the relationship curve between bit signal-to-noise ratio and frequency synchronization error is drawn.)