On Using Contact Expectation for Routing in Delay Tolerant Networks

Conventional routing algorithms rely on the existence of persistent end-to-end paths for the delivery of a message to its destination via a predesigned path. However, in a delay tolerant network (DTN), nodes are intermittently connected, and thus the network topology is dynamic in nature, which makes the routing become one of the most challenging problems. A promising solution is to predict the nodes´ future contacts based on their contact histories. In this paper, we first propose an expected encounter based routing protocol (EER)which distributes multiple replicas of a message proportionally between two encounters according to their expected encounter values. In case of single replica of a message, EER makes the routing decision by comparing the minimum expected meeting delay to the destination. We further propose a community based routing protocol(CR) which takes advantages of the high contact frequency property of the community. The simulations demonstrate the effectiveness of our proposed routing protocols under different network parameters.