Abstract: To solve the problem of low delivery ratio caused by intermittent network, DTN adopt multiple-copy routing to ensure the efficiency of message delivery. But in real situation, because the buffer of the node is limited, the network is congested when the number of message in network is larger than the sum of the buffer of the nodes. To deal with the congestion of the network, this paper drops the messages reasonably by defining the priority of message, and the priority is determined by the quality of the messages in the buffer of the node. The results show that this congestion control strategy can improve the network performance in congestion environment.

Key words: Delay Tolerant Networks（DTN）, epidemic routing, congestion control, quality of message

摘要： 为了解决受限网络环境所带来的低的递交率的问题，DTN（Delay Tolerant Networks）通常采用多拷贝路由（multiple-copy routing）机制来实现报文的有效递交。但在实际情况下，网络中节点的缓存是受限的，当网络中的总报文数大于所有节点的缓存容量和时，网络就发生了拥塞。针对网络拥塞，通过计算节点缓存中的报文质量（Quality of Message）以确定报文丢弃的优先级，合理地丢弃报文控制拥塞。仿真结果显示与其他拥塞控制策略相比，该路由策略能得到更好的网络性能。

关键词: 时延容忍网络（DTN）, 蔓延路由, 拥塞控制, 报文质量