中文摘要：

水声信道的时变和频变特性是影响通信性能的重要因素,基于此,对水声信道的时变特性进行研究.使用一阶自回归（A R ）模型对水声信道进行建模,通过信号多径比（SMR）来衡量时变信道的多径衰落程度,提出一种衡量时变信道下Rake接收机性能的标准和D S S S系统下的等效SMR, 并研究时变信道对Rake接收机的影响和直接序列扩频（DSSS）对时变多径信道的改善,以期为时变信道仿真提供一些有益的参考.

英文摘要：

The time varying and frequency varying characteristics of underwater acoustic （UWA） channel play a vitalpart in communication. Based on this, this paper focused on time varying characteristic of UWA channel with one orderauto regressive （A R） mode and signal multi-path ratio （SMR） to depict UWA channel and measure the multipathfading degree of time varying channel, a standard to evaluate Rake receiver over time varying channel and anequivalent SMR of DSSS system were proposed. The effect of time varying channel to Rake receiver and the improvementof time varying multi-path channel for direct sequence spread spectrum （DSSS） were explored, in order to providesome instrumental reference to time varying channel simulation.