The Delay-Tolerant network(DTN) is a wireless network, in which links between nodes may be disconnected frequently. In DTNs, packets are mainly delivered in a “store-carry-forward” manner, which is different from the “store-and-forward” method used in conventional networks. However, due to the short contact duration between nodes in network and the limited buffer size of the nodes,the packets in the forwarding path may be easily lost without considering an effective buffer schedule policy. For the above characteristics of the network itself, in this paper we propose a buffer schedule algorithm to forward data in the nodal buffer in order of the average contact frequency between the current node's neighbor nodes and the corresponding packet's destination node combined with the epidemic routing protocol. And the performance of the proposed algorithm is evaluated on the NS-2 simulation platform. Final simulation results show that its performance metrics, including the increase in data delivery rate, decrease in end-to-end delay and reduction of network overhead, are improved significantly with limited network resources.
