Abstract: Delay Tolerant Network（DTN） is a kind of restricted network. Due to the unstable delivery paths and high delivery latency in DTN, the congestion control methods applied in traditional networks are not suitable here. This paper proposes an Adaptive Congestion Control mechanism based on Node State（ACC-NS）. To satisfy different kinds of quality requirements, messages are classified into special messages and general messages. The special messages ask for higher delivery ratio. Nodes are classified into three levels according to their congestion state. Each node decides reception action based on its congestion state and current buffer usage ratio. To delete the redundant message copies, VACCINE and message encounter based countering method are combined. Compared with the other two existing routing protocols, simulation results show that ACC-NS achieves better performance.

Key words: delay tolerant networks, congestion control, Quality of Service（QoS）, congestion detection

摘要： 由于延迟容忍网络（DTN）的不稳定连接和高延时特性，传统的拥塞控制方法并不适用于DTN。提出一种基于节点状态的自适应拥塞控制机制（ACC-NS）。为满足不同的服务质量需求，将网络中的消息分为普通消息和特殊消息，其中特殊消息要求更高的传输率。根据节点的拥塞程度将节点状态分为三个等级，每个节点根据自己所处的拥塞状态和当前缓存空间使用率自主决策消息的接收行为。将VACCINE和基于消息相遇计数方法进行结合，以清除冗余消息副本。将ACC-NS和另两种经典的路由协议进行对比，ACC-NS实现了更好的性能。

关键词: 延迟容忍网络, 拥塞控制, 服务质量, 拥塞检测