More than two-thirds of the world’s surface is covered by water. It plays an important role in our economic existence, including in major verticals such as oil and gas, shipping and tourism.
As the Internet of Things proliferates, questions arise as to how IoT will manifest itself underwater given that radio waves degrade over distance in seawater, and underwater acoustic communication (which does actually work okay) is easily eavesdropped on and isn’t stealthy.
To make the underwater Internet of Things happen, light is the answer, some say. Researchers at King Abdullah University of Science and Technology (KAUST) in Thuwal, Saudi Arabia, are proposing underwater optical communications. They’re investigating simultaneous lightwave information and power transfer (SLIPT) configurations, which they’re using to transmit energy and data to underwater electronic devices. Recently, the researchers announced a breakthrough experiment in which they were able to achieve an underwater, two-way transmission of data and power over 1.5 yards between a solar panel-equipped sensor and a receiver.
The SLIPT system will be more usable than wires strung. And in the case of human underwater equipment inspections, for example, SLIPT will be less prone to error than hand signals and less prone to audible confusion than ultrasound voice-based communicators. Remarkably, to this day, hand signals are still a common form of communication between divers.
“SLIPT can help charge devices in inaccessible locations where continuous powering is costly or not possible,” said Jose Filho, a PhD student at KAUST, in an article on the school’s web site.
Filho, who has been involved in developing the laser project, envisages ships or boats on the water’s surface beaming optical communications to underwater vehicles or IoT sensors on the ocean floor. The lasers would simultaneously communicate with and power underwater robots and devices. Return data is relayed to the surface vessel, which then communicates to land bases or data centers via RF (radio).
Surface buoys – or even unmanned aerial vehicles (drones) flying well above turbulent waves – could be used to inject power down to the seabed surface and, at the same time, receive data, researchers believe.
The school explains that there’s still much development that needs to be performed before SLIPT is operational, but it sees potential. “Underwater optical communication provides an enormous bandwidth and is useful for reliably transmitting information over several meters,” co-first author Abderrahmen Trichili said in the article.
KAUST, located on the Red Sea coast, has been involved in this area of technical exploration for some years. It was involved in developing some early, record-breaking underwater data communications. In 2015 it ran a 4.8 gigabit per second, 16-QAM-OFDM transmission with a 450-nanometer laser. OFDM, or Orthogonal Frequency Division Multiplexing, splits single data streams into multiple channels to reduce interference.
Interestingly, seas and oceans are becoming increasingly important to data centers. Large swaths of the world’s population are found on or near coasts, rather than inland, and we’re seeing a shift towards edge-style computing that positions resources closer to sources of data. There’s also a need for compute cooling, which ocean water can provide. Even wave energy as a method of powering servers means sea and data are becoming intertwined.
Microsoft launched an undersea water-cooling data center 117 feet below the water surface in 2018. Additionally, garden-hose-sized cables carry almost all global, public Internet traffic underwater, across oceans and between continents. It’s not done through satellite, as many imagine.
So, this is not a brand-new synergy. Apart from the eco-monitoring drivers, one of the likeliest and most important reasons that ocean-based computing is being explored keenly is that there isn’t any rent payable or jurisdictional ownership on the high seas.
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