Engineering the World's First Underwater WiFi

The problem with underwater communication

With our current technology, divers use hand signals, radio, or acoustic or digital light signals to communicate. While these allow fairly effective communication, they have their limitations. 

Acoustic signals support long distances, but with a very limited data rate. Visible light can travel far and carry lots of data, the problem is that the narrow light beams require a clear line of sight between transmitters and receivers. Radio, meanwhile, can only carry data through short distances underwater. At the moment, wirelessly streaming video from under the sea simply isn't possible. 

That's a shame because video streaming provides a huge opportunity for scientific observation. "People from both academia and industry want to monitor and explore underwater environments in detail," lead author Basem Shihada explained in a press release. 

Submerged WiFi

In order to help provide a solution, Shihada's team, from King Abdullah University of Science and Technology in Saudi Arabia, built an underwater wireless system that they've dubbed 'Aqua-Fi.'

Aqua-Fi supports internet services, such as multimedia message sending via either LEDs or lasers. The LEDs provide a low-energy short-distance communication option, while lasers need more power but can carry data further.

The researchers built an Aqua-Fi prototype — detailed in their study published in IEE Explore — using green LEDs and a 520-nanometer laser. Both of these were used to send data from a small, simple computer to a light detector connected to another computer. 

The first computer converted photos and videos into a series of 1s and 0s, which were then transferred via a light beam that turns on and off at very high speeds to transmit the signal. The light detector senses the variation in the light speed and translates it back into the computer language of 1s and 0s. This, in turn, is converted by the receiving computer into the streamed footage or other multimedia.

In the real world, Aqua-Fi would use radio waves to send data from a diver's smartphone to a "gateway" device attached to their gear. Much in the same way that a WiFi booster works, this gateway sends the data via a light beam to a computer at the surface that is connected to the internet via satellite.

Obstacles to overcome

During their tests, the team was able to record a maximum data transfer speed of 2.11 megabytes per second and an average delay of 1.00 millisecond for a round trip. "This is the first time anyone has used the internet underwater completely wirelessly," says Shihada.

While that is impressive, there are several obstacles the researchers still need to overcome. "We hope to improve the link quality and the transmission range with faster electronic components," explains Shihada. What's more, the light beam has to remain perfectly aligned with the receiver in moving waters, so the team is considering a spherical receiver that can capture light from all angles.

"We have created a relatively cheap and flexible way to connect underwater environments to the global internet," says Shihada. "We hope that one day, Aqua-Fi will be as widely used underwater as WiFi is above water."

Seeing as underwater WiFi will have 5G to catch up with, that would be quite an achievement.