Cooperative transmission in delay tolerant network

The delay tolerant network (DTN) is an emerging concept, which is used to describe the network, where the communication link may disrupt frequently. To cope with this problem, the DTN uses the store-carry-forward (SCF) transmission mode. With this policy, the messages in the DTN are transmitted based on the nodes' cooperation. However, the nodes may be selfish, so the source has to pay certain rewards for others to get their help. This paper studies the optimal incentive policy to maximize the source's final utility. First, it models the message spreading process as several ordinary differential equations (ODEs) based on the mean-field approximation. Then, it mathematically gets the optimal policy and explores the structure of the policy. Finally, it checks the accuracy of the ODEs model and shows the advantages of the optimal policy through simulation and theoretical results respectively.