Internet of Underwater Things (IoUTs) has been proposed to autonomously monitor and collect data from aquatic environments. In these networks, the acoustic channel is currently considered as the most viable technology for underwater wireless communication among the nodes. By using acoustic modems, underwater sensor nodes are able to autonomously and collaboratively sense the area of interest and report collected data to a monitoring center through multi-hop underwater wireless communication. However, underwater wireless communication through acoustic channels is daunting, due to the limited bandwidth, multipath propagation, shadowing zones, high and variable delay, noisy environment and high energy cost. These characteristics impair data collection and shorten the IoUT lifetime. In this paper, we propose a novel power controlbased opportunistic (PCR) routing protocol for IoUTs. The proposed protocol considers the neighborhood density, link quality, distance, packet advancement, and energy waste to select the suitable transmission power level at each sensor node. Accordingly, each neighboring node eligible to continue forwarding the data packet is considered as a next-hop forwarder node if its inclusion in the next-hop nodes candidate set does not increase the energy waste in the considered hop. Numerical results showed that the proposed protocol improves data delivery rate while maintaining the energy cost at levels comparable to the related work.

Introduction

Oceans cover more than 2/3 of Earth’s surface and they play a fundamental role to support life on our planet. Oceans have absorbed more than 1/4 of carbon dioxide (CO2) produced by humans since 1800 and 2/3 of the heating produced by human activities since 1995 [1]. Moreover, they are one of the main sources of food and mineral resources and they serve as a transportation medium for people and goods. Despite all benefits, it is estimated that no more than 5% of the oceans’ volume has been seen by human eyes [2]. The critical challenge, therefore, is how we can change this worrying reality. Overall, ship missions for ocean monitoring are expensive and might jeopardize humans life, due to extreme weather conditions, for instance. Hence, there is a growing demand for the development of aquatic monitoring technologies that can autonomously collect data from oceans and events beneath them. In this regard, Internet of Underwater Things (IoUTs) [3], as an evolution of underwater wireless sensor networks (UWSNs) [4, 5], emerges as a cost-effective solution for increasing maritime awareness through the large-scale and real-time monitoring of aquatic environments. IoUTs will be composed of intelligent sensor nodes (floats) that will collaboratively sense the area and events of interest and them report collected data to a cloud computing system [6]. To do so, the underwater sensor nodes will be equipped with acoustic modems that will enable underwater wireless communication among them.