一种面向机会网络路由的最优停止决策方法

投递延迟是机会网络的一个重要指标，给定节点缓存和消息副本数目限制，如何选择合适的节点复制消息成为一个关键问题.提出一种基于最优停止理论的路由决策方法（OSDR）.OSDR 将每个时隙上所遇节点和目标节点的平均相遇时间看做一个随机变量，根据该随机变量的统计特性得到一个停止观察、复制消息的规则，该规则呈现简单的阈值结构，即当某个时隙上所遇节点和目标节点的平均相遇时间小于给定阈值时即复制消息. OSDR 可以在较小的相遇间隔和等待成本之间进行折衷，实现数学期望意义上的最小消息投递延迟.介绍了OSDR 的网络模型、最优停止规则的存在性证明过程以及计算方法.模拟实验结果表明，OSDR 相对其他方法，在投递成功率、投递延迟等方面具有明显优势.

Optimal Stopping Decision Method for Routing of Opportunistic Networks

Delivery delay is an important performance metric in opportunistic networks. With given buffer size and copy numbers, how to select appropriate nodes to replicate message is the key to minimizing delivery delay. To solve this problem, this paper proposes an optimal stopping decision method for routing opportunistic networks (OSDR). With OSDR, the average meeting time between a node and the destination is regarded as the forwarding utility of the node. A node carrying a message observes the random forwarding utilities of the nodes it meets, and replicates messages according to the optimal stopping rule, which turns out to be threshold-based. By making tradeoffs between the forwarding utility and waiting cost, OSDR achieves the minimum delivery delay expectation. This paper introduces the OSDR network model and existence proof and calculation of optimal stopping rule in detail. Simulation results show that OSDR outperforms other protocols in delivery delay and delivery rate.