Abstract
Advances in sensing and wireless communication technologies have enabled a wide spectrum of Outdoor Wireless Sensor Network (OWSN) applications. Some applications require the existence of a communication backbone federating different OWSN sectors, in order to collaborate in achieving more sophisticated missions. Federating (connecting) these sectors is an intricate task due to the huge distances between them, and due to the harsh operational conditions. A natural choice in this case is to have multiple Relay Nodes (RNs) that provide vast coverage and sustain the network connectivity in harsh environments. However, these RNs are not cheap and, thus, a constraint on their count holds. That being said and considering the harsh conditions in outdoor environments, placement of the RNs becomes crucial and has to be in a way that tolerates failures in communication links and deployed nodes. In this paper, we propose a novel approach in optimizing the RNs placement, called ST-DT approach, with the objective of federating different OWSNs with the maximum connectivity under a cost constraint on the RNs count to be deployed. The performance of the proposed approach is validated and assessed through extensive simulations and comparisons assuming practical considerations in large-scale outdoor environments.