A Survey on Deployment Algorithms in Underwater Acoustic Sensor Networks

Node deployment is one of the fundamental tasks for underwater acoustic sensor networks (UASNs) where the deployment strategy supports many fundamental network services, such as network topology control, routing, and boundary detection. Due to the complex deployment environment in three-dimensional (3D) space and unique characteristics of underwater acoustic channel, many factors need to be considered specifically during the deployment of UASNs. Thus, deployment issues in UASNs are significantly different from those of wireless sensor networks (WSNs). Node deployment for UASNs is an attractive research topic upon which a large number of algorithms have been proposed recently. This paper seeks to provide an overview of the most recent advances of deployment algorithms in UASNs while pointing out the open issues. In this paper, the deployment algorithms are classified into three categories based on the mobility of sensor nodes, namely, (I) static deployment, (II) self-adjustment deployment, and (III) movement-assisted deployment. The differences of the representative algorithms in aspects of sensor node types, computation complexity, energy consumption, deployment objectives, and so forth, are discussed and investigated in detail. 1. Introduction Recently, advances in wireless sensor networks (WSNs) have motivated the development of underwater acoustic sensor networks (UASNs), which have become a compelling technology to enable and enhance applications such as environment monitoring, resource exploration, disaster prevention, pollution detection, and military surveillance [1]. UASNs are composed of different kinds of sensor nodes (i.e., surface sink, underwater sensor nodes, etc.) to collaboratively perform monitoring tasks over a three-dimensional (3D) space. A three-dimensional UASN architecture is shown in Figure 1. UASNs consist of static sensor nodes which are deployed both on the water surface and underwater and automatic mobile sensor nodes to perform collaborative monitoring tasks over a given monitored space. Static sensor nodes usually consist of a sensing device, a microcontroller, and an acoustic transceiver with a limited amount of energy. Automatic mobile sensor nodes such as autonomous underwater vehicles (AUVs), unmanned underwater vehicles (UUVs), and low-power gliders typically have plenty of energy which can be supplemented when needed. According to the application requirements, different kinds of sensor nodes can be deployed in UASNs, that is, surface sinks, underwater nodes, bottom nodes, and automatic mobile nodes. Surface sinks are