中文摘要：

水下网络使用水声信道进行通信,但水声信道低带宽和高传播时延的特点使介质访问控制协议的设计存在较多难点。为此,对冲突避免多址接入（MACA）协议进行改进,提出PE-MACA协议。根据优先权原则使节点同时与多个邻居节点通信,在数据传输时使用高响应比优先算法,并利用半争用算法进行信道切换。仿真结果表明,与MACA协议相比,PE-MACA可有效提高信道利用率和网络吞吐率。

英文摘要：

Underwater networks use the acoustic channel to communicate with each other. However,there are many difficulties in designing the Media Access Control（ MAC） protocol due to low bandwidth and high propagation delay of the acoustic channel. In order to solve these problems,this paper improves Multiple Access with Collision Avoidance（ MACA） protocol and proposes PE-MACA protocol. In this improved protocol,nodes can communicate with multiple neighbor nodes according to the priority principle. The Highest Response Ratio Next（ HRN） algorithm is used to transfer data and the half-contention algorithm is used to switch the channels. Simulations result shows that,compared with MACA protocol,PE-MACA can improve channel utilization rate and network throughput effectively.