Self-deployment of sensors for maximized coverage in underwater acoustic sensor networks

While self-deployment/reconfiguration of terrestrial wireless sensor networks (WSNs) has been studied extensively, such selforganization has just started to receive attention for Underwater Acoustic Sensor Networks (UWSNs). Particularly, self-deployment of sensor nodes in UWSNs is challenging due to certain characteristics of UWSNs such as three dimensional (3-D) environment, restrictions on node movement and longer delays in communication. Given these characteristics, self-deployment of sensor nodes should not only ensure the necessary coverage but also guarantee the connectivity for data transmission as in the case of terrestrial WSNs. In this paper, we propose a distributed node deployment scheme which can increase the initial network coverage in an iterative basis. Assuming that the nodes are initially deployed at the bottom of the water and can only move in vertical direction in 3-D space, the idea is to relocate the nodes at different depths based on a local agreement in order to reduce the sensing overlaps among the neighboring nodes. The nodes continue to adjust their depths until there is no room for improving their coverage. We tune the parameters of the algorithm to also provide connectivity of the network with a surface station. We compared the coverage and connectivity performance of this distributed scheme with distributed/semi-distributed baseline schemes and centralized schemes which can provide optimal coverage/connectivity. We also provide several observations regarding the coverage/connectivity performance and message/travel/time complexity of the proposed approach.