Abstract
The research in this letter focuses on geographic routing in Delay/Disruption Tolerant Networks (DTNs), by considering sparse network density. We explore the Delegation Forwarding (DF) approach to overcome the limitation of the geometric metric which requires mobile node moving towards destination, with the Delegation Geographic Routing (DGR) proposed. Besides, we handle the local maximum problem of DGR, by considering nodal mobility and message lifetime. Analysis and evaluation results show that DGR overcomes the limitation of the algorithm based on the given geometric metric. By overcoming the limited routing decision and handling the local maximum problem, DGR is reliable for delivering messages before expiration lifetime. Meanwhile, the efficiency of DGR regarding low overhead ratio is contributed by utilizing DF.