When it comes to communicating under the seas, humans have long struggled to find suitable tools. Radio and sonar systems are typically used but they suffer from a variety of downsides. Researchers at the King Abdullah University of Science and Technology in Thuwal, Saudi Arabia, put their heads together and came up with a new solution: Aqua-Fi.
A team of scientists at the university recently developed a system that was able to place a brief Skype call while underwater—a breakthrough in a field that had only been able to send small snippets of data in the past. Aqua-Fi leverages a combination of lasers and off-the-shelf components, such as a Raspberry Pi computer as the modem, to create a bidirectional wireless connection for underwater devices that can easily connect to and function as part of the broader internet.
“In 2019, we talked about connecting everything with everything and we put together a vision on how to connect the underwater devices with the Internet. Aqua-Fi will be the main element for the futuristic internet of underwater things network, where it will connect underwater stations, divers, autonomous vehicles, etc. with the terrestrial networks,” said Bassem Shihada, associate professor of computer science at the university.
“The future of Aqua-Fi based network will be a scalable, flexible, and efficient communication solution for and with the underwater environment.”
The team at King Abdullah University of Science and Technology took waterproofed smartphones and used a regular Wi-Fi signal to connect the devices to the underwater Raspberry Pi.
According to the researchers, the Raspberry Pi was able to convert the wireless signal to an optical laser signal that was subsequently beamed to a receiver that was attached to a surface buoy.
Shihada and an electrical engineering professor, Mohamed Slim-Alouini, said in an email interview that they initially wanted to leverage the use of Wi-Fi underwater for short distances of about one meter or less.
Once they did that, their nine-person team boosted the connectivity to longer distances using either high-power LEDs for up to 10 meters or lasers for beyond 10 meters. After more than a year of work, Aqua-Fi was officially born in late 2019 with a successful demo.
Slim-Alouini explained that in 2015, he was fascinated by underwater wireless optical communications as an alternative solution for short-range marine communication links. By 2017, their team was able to transmit a 1.2-gigabit file underwater using a blue laser.
He first started work on optical underwater wireless communication systems by focusing on the characterization and modeling of the underwater optical channel. Slim-Alouini then collaborated with fellow professor Boon Ooi to design, develop, and test the system.
“More than 70% of Earth is covered with water and just 5% of Earth’s oceans have been explored and mapped. So clearly there is a great potential and need for underwater engineering in general. There is also a greater need for reliable high-speed underwater communication and networking for scientific data collection, underwater resources exploration and underwater infrastructure monitoring,” Slim-Alouini said.
“In this context, by delivering internet in an underwater environment with Wi-Fi-like quality, Aqua-Fi helps divers and diving robots achieve these goals.”
Shihada said they were able to demonstrate the Aqua-Fi by holding a conversation through a Skype call held over Aqua-Fi.
In order for the Aqua-Fi to hold a connection, the lasers have to stay aligned and the power banks have to hold their energy. The alignment of the lasers is one of the main challenges the professors are facing in producing versions that could work in the real world, according to Shihada, because strong waves are enough to knock the lasers off alignment.
“Aqua-Fi can go as deep as the laser can propagate in the water. The range and the data rates are related. With longer range, the data rate is reduced. This often can be solved using relays and there are several ongoing research projects about underwater relay deployment for underwater internet and underwater sensors,” Shihada said, adding that they are looking at a number of potential solutions to the problem, including low-power guide lasers that could scan for receptors if the connection is broken.
“Lasers, both green and blue ones, can propagate in water environments with high data rates. The selection of lasers was essential to facilitate enough connectivity depth. We can use acoustic-based communication technologies, however these technologies are extremely complicated, require special hardware, and gain a very limited throughput that is insufficient for today’s bandwidth hungry internet applications.”
Potential use cases
Right now, it is difficult to use Wi-Fi underwater and current systems can really only transmit signals for up to one meter. The potential applications of this new Aqua-Fi technology are endless, particularly as dozens of companies like Microsoft consider how data centers could be installed and operated under water.
Shihada admitted that wide commercial application of the technology is a little ways off, but said the team is making great strides toward their goal of deploying the idea with underwater data centers as well as for sea conservation efforts around coral reefs.
Aqua-Fi would be useful for intelligent monitoring under water for industries like oil and gas exploration, operation or transportation as well as environmental and pollution monitoring, the professors said. It would also help with scientific studies of ocean temperature and studies of marine life, natural disasters and natural resources, Shihada noted.
“Since Aqua-Fi is Wi-Fi-based, it can also transfer the GPS coordinates of the devices underwater. Without Aqua-Fi, GPS signals can not propagate in sea water! Therefore, underwater devices can somehow know their location from above,” Shihada theorized.
He added that it could be used to help with the maintenance of preinstalled pipelines and cables. There are also more fun applications like remote live snorkeling or fishing as well as underwater sports.
Slim-Alouini noted that Aqua-Fi would also be helpful for underwater search and rescue operations. He also said the team is looking to develop and test a practical underwater Pointing, Acquisition, and Tracking scheme that allows the undersea laser link to remain aligned and achieve line-of-sight communication under all kinds of mobility conditions.