A Game-Theoretic Approach to Supporting Fair Cooperation in Delay Tolerant Networks

Delay Tolerant Networks (DTN) comprise nodes with small and limited resources, such as power and storage space. The constraint of resources, together with the mobility and sparsity of DTN nodes, trigger an intermittent connection among the nodes and require delay tolerance of their applications. In such a challenging environment, decentralized routing protocols are implemented with the main concern of maximizing data delivery and minimizing resource usage. These protocols rely on the participation of the network nodes in receiving and storing data packets, collecting and processing information about the network topology to find the next best-hop, and replicating and spreading packets of each other. From a network perspective, all nodes are required to participate in delivering packets of each other. From a node perspective, minimizing resource consumption is the most important. We define fair cooperation as the degree of cooperation where all nodes are satisfied with their participation in the network routing services. We propose a distributed game theoretic approach that computes a node utility function to achieve fair cooperation. We implemented the method into several DTN routing protocols and compared their performance. Results show that by tuning the parameters of the utility function, fairness among the nodes is improved, and delivery cost is reduced, which motivates the nodes to cooperate.