Coordinating replication decisions in multi-copy routing for opportunistic networks

One of the dominant approaches in coping with the intermittent connectivity of opportunistic networks is packet replication. However, the need for a distributed operation forces the nodes carrying a message copy to make replication decisions without taking into account the replication state of other nodes. This strategy can lead to the creation of an excessive number of replicas thus exhausting the limited node resources such as energy and storage capacity. In this paper, we propose a simple yet efficient method which, without incurring any additional cost, allows nodes to share information about the replication process in order to avoid unnecessary replication. Our approach significantly reduces the routing cost without sacrificing delivery rate. Furthermore, it is generic in the sense that it can be implemented regardless of the utility metric used for making the replication decision. We validate the performance gains of our algorithm through analysis as well as extensive simulations.