Internet of Buoys: An Internet of Things Implementation at Sea

TL;DR

This paper investigates sea-based IoT applications by measuring path loss for low-height antennas, comparing models, and exploring connectivity options like NB-IoT and Sigfox for maritime monitoring.

Contribution

It evaluates the accuracy of existing sea path loss models at low antenna heights and assesses the feasibility of NB-IoT and Sigfox for maritime IoT deployments.

Findings

Round earth loss model is inaccurate at low antenna heights.

ITU-R P.2001-3 and Bullington models better match measurements.

NB-IoT and Sigfox are viable for sea IoT applications.

Abstract

Internet of Things (IoT) applications are emerging in many different areas, including maritime environments. One of the applications in this area is the monitoring of buoys at sea. To realize wireless tracking of buoys, an accurate prediction of the path loss in an open-sea environment is essential. So far, channel measurements at sea have mainly been conducted with antennas placed a couple of meters above the sea surface, which is higher than the buoys themselves. Therefore, we investigated the validity of the published channel models at sea by means of path loss measurements using a LoRa link with a transmitter antenna height of 0.35 m and a base station antenna height of 2.65 m and 5.2 m. Our results show that the round earth loss model is not accurate at these antenna heights. The ITU-R P.2001-3 model and a model by Bullington show a better agreement with our measurements. However, the difference between our two measurement campaigns shows that more investigation is needed on the dependence of the path loss on the sea state. Additionally, the availability of Sigfox, Narrowband Internet of Things (NB-IoT), and The Things Network at sea has been explored. We found that NB-IoT and Sigfox can be used for IoT applications in the tested area at low antenna heights.