News of Kongsberg Discovery’s milestone in its autonomous underwater vehicle (AUV), HUGIN Endurance, was big news, because 10 hours into a dive the AUV was able to complete the rest of the mission autonomously. Although work to improve AUVs’ operational efficiency and the autonomy in their name is ongoing, this milestone shows the serious time and investment companies operating this space put into the Internet of Underwater Things, AKA IoUT.
What is IoUT?
The Internet of Things takes many forms, and the Internet of Underwater Things (IoUT) is one of them. The emergence of IoUT is expected to impact marine research, oceanography and exploration, using sensor networks, autonomous vehicles and communication systems to improve our understanding and knowledge of the oceans.
IoUT refers to a network of smart sensors, devices, autonomous underwater vehicles (AUVs) and communications systems that facilitate the exchange of data wirelessly while underwater. AUVs, capable of operating autonomously or in collaboration with one another, are used to monitor different parameters such as temperature, salinity, pH levels and marine life behaviour.
One of the greatest advantages offered by IoUT is its potential to provide continuous, real-time data. In contrast with traditional oceanographic research, which relies on manually deployed instruments that collect data over limited time periods, IoUT-enabled systems can remain operational for extended durations. These systems can gather long-term datasets, which are valuable for improving our understanding of processes like ocean circulation, climate change, and biodiversity shifts.
For marine biology, IoUT-enabled sensors can track the movements of marine animals, monitor their behaviour, and observe how environmental changes affect their habitats. This information could be influential in establishing more effective conservation strategies.
In deep-sea exploration, IoUT is particularly valuable. The harsh conditions of the deep ocean – immense pressure, near-freezing temperatures, and complete darkness – make human exploration almost impossible. However, IoUT-equipped AUVs and remotely operated vehicles (ROVs) can venture into these regions, capturing high-resolution images, collecting samples, and relaying data to surface stations.
Challenges for IoUT communication systems
The deployment of IoUT technologies is not without its challenges. One of the most significant challenges is to establish reliable communication systems in underwater environments. Unlike on land, where wireless communication relies primarily on radio frequency (RF) signals, the propagation of RF signals underwater is limited due to absorption by water.
News earlier this year of WSense and Alcatel Submarine Networks (ASN) signing a MoU to create wireless communication systems shows that this remains a hurdle. Wireless infrastructure on land is well established; underwater, it’s not. The MoU will see both companies working towards developing underwater Wi-Fi and “creating something ground breaking,” as Chiara Petrioli, CEO of WSense.
Three types of communication technologies have emerged as potential solutions: acoustic, optical, and RF systems. Each of these has its own advantages and challenges in the context of IoUT.
Acoustic communication:
Acoustic communication is arguably the most widely used method for underwater communication, particularly in deep-sea applications. Acoustic signals travel relatively well in water, especially over long distances, making them well-suited for applications such as oceanographic data collection and submarine communication. However, acoustic communication comes with several drawbacks.
One major challenge is the limited bandwidth available for acoustic signals, which restricts the amount of data that can be transmitted at any given time. Acoustic signals are also prone to interference from environmental noise, such as waves, marine life, and human activity. This can degrade signal quality and reduce the reliability of data transmission.
Another issue is the latency associated with acoustic communication. Sound waves travel significantly slower in water than electromagnetic waves do in air, leading to delays in data transmission, particularly over long distances. For real-time monitoring applications, this latency can pose challenges in achieving instantaneous data transfer.
Optical communication:
Optical communication, which uses light to transmit data, offers higher bandwidth compared with acoustic systems, which allows for faster data transmission rates. This makes optical communication an attractive option for applications that require the transmission of high-resolution video or large amounts of sensor data.
However, optical signals are limited by the high absorption and scattering of light in water. As a result, the range of optical communication is typically restricted to short distances, often less than 100 metres. Additionally, water turbidity, which can vary depending on location and environmental conditions, can be a hindrance to the effectiveness of optical systems.
Despite these limitations, optical communication is increasingly being explored for specific IoUT applications, particularly in shallow waters or where high-speed data transfer is critical.
Radio Frequency (RF) communication:
Although RF signals are severely attenuated underwater, they can still be used for short-range communication, particularly in applications close to the surface or in shallow waters. Recent research has focused on developing RF communication systems that are optimised for underwater environments, using low-frequency signals that experience less attenuation.
While RF systems have the advantage of enabling wireless communication between underwater and surface devices, their limited range and high energy consumption are still barriers. RF systems may not be suitable for deep-sea applications, where acoustic communication remains the more viable option.
To address these communication challenges, researchers are exploring hybrid systems that combine multiple communication methods. For example, a hybrid system could use acoustic communication for long-distance data transmission and optical communication for short-range, high-bandwidth applications. Such systems would leverage the strengths of each communication method while mitigating their respective weaknesses.
Additionally, advances in signal processing, modulation techniques, and error correction algorithms are helping to improve the reliability and efficiency of underwater communication systems. These developments are aiding the large-scale deployment of IoUT networks, particularly for ocean exploration and remote monitoring applications.
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