NEC has been developing underwater acoustic equipment including defense sonar for over 90 years.
Currently, they are focusing on developing marine business using underwater acoustic equipment, and as part of this effort, they are demonstrating stable two-way, long-distance communication underwater using an underwater acoustic communication module. A communication module is installed in an experimental underwater unmanned vehicle to remotely control the underwater unmanned vehicle as it navigates at 2-3 knots in an ocean area 2.5 kilometers away, and to receive data collected by the underwater unmanned vehicle. Confirmed the use case for communication between the two parties.

This communication module was realized by combining the company’s sonar-related technology, including transducer technology and underwater equipment manufacturing technology, with NTT’s space-time equalization technology.
Toshiro Yamauchi of NEC’s Maritime Security Division said, “Our ultrasonic transducer technology is a world-class technology that can receive high-output, minute sounds.Also, it has been used in simulations to understand how sound waves travel underwater. They have high technical capabilities and are making use of these technologies”.

In underwater communication, sound has the longest distance, so it has an advantage over light and radio waves. However, there are also issues unique to sound.
One is reflection. Sound can reflect off the ocean floor or ocean surface, resulting in several waves overlapping at the receiving and transmitting destinations.
The other is the Doppler effect. The frequency changes when the source of the sound wave moves or when the receiver moves. Unless this is resolved, proper communication will not be possible.
“Underwater communication has been around for a long time, and communication in the depth direction is relatively easy, but in order to deploy multiple underwater drones, communication technology in the horizontal direction is essential. NTT’s spatio-temporal equalization technology “We conducted demonstration experiments using this technology and combining it with NEC’s ultrasonic transducer technology and watertight technology.” (Mr. Yamauchi)
Previously, underwater devices such as underwater drones were connected by cables and could only capture a portion of the ocean, but with underwater acoustic communication modules, underwater devices can now move freely and capture more detailed underwater images. You will be able to understand it.

Examples include inspections of offshore equipment such as offshore wind power generators, calculations of CO2 absorption by “blue carbon,” carbon derived from carbon dioxide absorbed from the atmosphere into the sea by the action of marine organisms, and fisheries and aquaculture. It is expected that marine businesses such as water quality data monitoring, resource exploration, and topographic surveys will expand.
“According to overseas research companies, Japan’s underwater acoustic communications market is expected to expand at an annual rate of more than 10%.Currently, various innovations are occurring, so we expect the market to expand even further,” says Yamauchi.
Regarding underwater acoustic communication modules, we will focus on research and development and demonstration experiments this fiscal year and next, aiming for commercialization in fiscal 2024.

In the future, they will also consider underwater solution integration.
NEC’s policy is to combine its various technologies to create a single system. As a key technology, we are aiming to commercialize an underwater acoustic communication module.
Mr. Yamauchi states, “We believe that it would be difficult for our company to cover everything on our own, so we plan to create an ecosystem and develop the ocean business by collaborating with a variety of partners.” .
Ultimately, we aim to create a society that can communicate everywhere, from the ocean floor to outer space.
“How do we bring the information acquired under the sea to the ground? For example, we are thinking of floating a buoy in the sea as a relay point. By connecting it to satellite communication, we can collect information from everywhere under the sea. “We also want to use mobile communications such as 5G and 6G and optical networks to cover every corner of the earth,” Yamauchi said.