Sensors to Increase the Security of Underwater Communication Cables: A Review of Underwater Monitoring Sensors

Abstract

Underwater communication cables transport large amounts of sensitive information between countries. This fact converts these cables into a critical infrastructure that must be protected. Monitoring the underwater cable environment is rare and any intervention is usually driven by cable faults. In the last few years, several reports raised issues about possible future malicious attacks on such cables. The main objective of this operational research and analysis (ORA) paper is to present an overview of different commercial and already available marine sensor technologies (acoustic, optic, magnetic and oceanographic) that could be used for autonomous monitoring of the underwater cable environment. These sensors could be mounted on different autonomous platforms, such as unmanned surface vehicles (USVs) or autonomous underwater vehicles (AUVs). This paper analyses a multi-threat sabotage scenario where surveying a transatlantic cable of 13,000 km, (reaching water depths up to 4000 m) is necessary. The potential underwater threats identified for such a scenario are: divers, anchors, fishing trawls, submarines, remotely operated vehicles (ROVs) and AUVs. The paper discusses the capabilities of the identified sensors to detect such identified threats for the scenario under study. It also presents ideas on the construction of periodic and permanent surveillance networks. Research study and results are focused on providing useful information to decision-makers in charge of designing surveillance capabilities to secure underwater communication cables.

Remote Sensing Systems for Ocean: A Review (Part 2: Active Systems)

“…Considering the limited applications of electromagnetic-based imaging systems (e.g., optical and LiDAR) in the underwater environment, the SONAR system has been the preferred solution to study bathymetry, morphology, and structure of ocean floor [278]- [282]. SONAR systems are mainly designed to detect and/or transmit the acoustic propagation between a target and a receiver for underwater applications.…”

“…In fact, passive SONAR systems use the frequency and variation of the received echoes over time to detect a target. On the other hand, active SONAR systems emit the acoustic wave using a transmitter and, then, measures the echoes bounced back from objects in oceans [278], [285]. This study only considers the active SONAR systems because they have been the mostly systems used in oceans [278], [282], [289]- [292].…”

“…Most of the available bathymetry data have been so far collected with the aid of different types of single-beam SONAR systems [285]. Although single-beam SONAR systems provide acceptable spatial resolution for underwater applications, their coverage is limited [278].…”

“…Although complex data are collected by the synthetic aperture SONAR systems, the main processing step is usually reducing the original complex image into a pure intensity image [299]. Synthetic aperture SONAR systems are capable of capturing SONAR images with the resolution of several centimeters over a range of up to several hundred meters [278]. This makes synthetic aperture SONAR systems efficient tools for various underwater applications, such as small object search, wreckage imaging, pipeline inspection, and underwater archaeology.…”

Legal regime regulating the laying and protection of submarine cables in the Republic of Croatia

“…Various sensor-based technologies are already available on the market that can be used for cable installation as well as for monitoring the marine environment. [2], [5], [6], [10], [11], [25] The laying of cables is preceded by a number of activities of both technical and legal nature. Based on the telecommunications network operators' or owners' business decisions, landing points are determined, where the submarine cables are then connected to the terrestrial cable network.…”