A secure, service priority-based incentive scheme for delay tolerant networks

Delay tolerant networks are resource-constrained networks, where nodes are required to cooperate with each other to relay messages (bundles) in a store-carry-forward fashion. Because of the constrained resources, some selfish nodes are reluctant to relay bundles for other nodes in order to save their own resources. Previous studies focus on one kind of credit-based incentive schemes in which a source pays credits (virtual coins) to intermediates to compensate for their resources consumption. Although these schemes can restrain selfish behaviors to a certain extent, they may cause an undesirable effect on some honest nodes, especially on boundary nodes and inactive nodes. To mitigate this issue, first we propose a service priority-based incentive scheme (SIS) where a relaying (viewed as a service) priority, instead of credits, is used as an incentive metric to stimulate nodes to fairly cooperate. In the SIS, a node which relayed more bundles is granted a higher service priority, and it will obtain a higher bundle delivery ratio correspondingly. Then, to deal with the potential attacks against the SIS, we also present three security solutions including the signature chain, cooperation frequency statistics, and combination clearance. We evaluate the proposed scheme on the opportunistic network environment simulator. The extensive results show that the SIS is able to improve the bundle delivery ratio of honest nodes and efficiently inhibits the selfish behaviors in comparison with credit-based incentive schemes. Copyright (C) 2015 John Wiley & Sons, Ltd.