Research On Incentive Scheme For Routing Protocol In Delay Tolerant Networks

Delay Tolerant Network (DTN) is a class of networks characterized by lack of guaranteed connectivity, low frequency of encounters between DTN nodes and long transmission delay within the network and limited resource. As a result, the message transmission process in DTN follows a store-carry-forward manner, and the in-transit bundle messages can be opportunistically routed. The existing routing protocols all assume that all nodes in the DTN are ready to forward packets for others. However, some nodes are reluctant to serve as the bundle relays to save their precious wireless resource. This will decrease the throughout of the entire network and degrade the performance of the network. The existing DTN incentive schemes focus on credit-based incentive scheme in which a sender pays forwarders credits for their assistance. However, these schemes have negative impact on inactive nodes and edge nodes, and will eventually result in degrade in the network throughput and delivery ratio. Furthermore, as the sender only pays credits to the nodes which have successfully forwarded messages, these schemes will also impair the fairness of the network.To solve the aforementioned problems, we propose a service-based reputation incentive scheme (SBRI) in which the service priority and reputation are used as incentive metrics to stimulate nodes to cooperate. In this scheme, the more packets a node forwards, the higher service priority and reputation the node obtains. As a result, the nodes with higher priority can get better network service. On the other hand, the nodes with lower priority only get poor service. In this scheme, the reputation of the node will decrease with the time if the node doesn’t forward bundle for other nodes. When the reputation of a node drops below the threshold, other nodes won’t forward messages for the node. Because in the actual applications of DTN, the mobile model of nodes usually base on social mobile model, we propose a social-based reputation incentive scheme which enhances the propagate ratio of the reputation and data via the node self-check and social-check reputation.We evaluate the scheme on opportunistic network environment (ONE) simulator, the results show that SBRI can balance the utilization rate of network resources among nodes by inhibiting the selfish behavior, improve the fairness of the network and increase the delivery ratio of honest nodes in comparison with credit-based incentive schemes. The stimulation results show that the proposed social-based reputation scheme can stimulate selfish nodes to forward packets and increase the delivery ratio of data.