延迟容忍网络中一种基于概率接纳和丢弃的拥塞控制算法

链路的间歇性连通以及稳定的端到端路径的缺乏使得延迟容忍网络（delay tolerant network）中经常采用“存储〖CD*2〗携带〖CD*2〗转发”的方式来保证消息传输的到达率。然而由于网络资源受限，该转发方式下产生的大量的消息副本将造成巨大的资源消耗，最终导致网络拥塞。提出一种基于概率接纳和丢弃（probabilistic acceptance and drop, PAD）的拥塞控制算法PAD。该算法结合了队列长度和输入/输出速率来检测拥塞，各个节点根据当前的拥塞状态来确定接收和丢弃消息的概率，从而实现较小的开销和较高的消息到达率。此外,基于生灭模型构造了消息副本数的连续时间马尔可夫链，并对消息到达率进行了理论分析。理论分析和仿真结果证明，与其他算法相比，PAD算法在保证较小的网络开销和较短的端到端延迟的同时，消息到达率显著地提高了130%以上。

A congestion control algorithm based on probabilistic acceptance and drop in delay tolerant network

Because of the intermittent connectivity and absence of stable end-to-end paths in delay tolerant networks, a store-carry forwarding protocol is often used to improve the delivery ratio. However, message replication may easily incur huge resource consumption and finally result i- network congestion. A probabilistic acceptance and drop (PAD) algorithm is proposed, which adaptively controls congestion for delay tolerant networks. In this algorithm, the queue length and input/output rate are combined to detect congestion. Based on the congestion state, each node determines the probability of accepting or dropping message to obtain a good trade-off between high delivery ratio and low overhead. Furthermore, based on the birth-death model, the continuous time Markov chain of message copies is constructed to analyze the delivery ratio of message. Theory analysis and simulation results how that, compared with other algorithms, the PAD algorithm increases the delivery ratio by more than 130 percent with shorter average end-to-end delay and less overhead.