Underwater Wi-Fi would benefit divers

Aquatic internet that sends data through light beams could enable divers to instantly transmit footage from under the sea to the surface, according to a study conducted by King Abdullah University of Science and Technology (KAUST) researchers and published in IEEE Communications Magazine.

Underwater communication is currently possible with radio, acoustic and visible light signals. However, radio can only carry data over short distances, while acoustic signals support long distances, but with a very limited data rate. Visible light can travel far and carry lots of data, but the narrow light beams require a clear line of sight between the transmitters and receivers.

Now KAUST researchers have built an underwater wireless system, Aqua-Fi, that supports internet services, such as sending multimedia messages using either LEDs or lasers. LEDs provide a low-energy option for short-distance communication, while lasers can carry data further but need more power.

The Aqua-Fi prototype used green LEDs or a 520 nm laser to send data from a small, simple computer to a light detector connected to another computer. The first computer converts photos and videos into a series of 1s and 0s, which are translated into light beams turning on and off at very high speeds. The light detector senses this variation and turns it back into 1s and 0s, which the receiving computer converts back into the original footage.

The researchers tested the system by simultaneously uploading and downloading multimedia between two computers set a few metres apart in static water. They recorded a maximum data transfer speed of 2.11 MBps and an average delay of 1 ms for a round trip. According to first author Basem Shihada, “This is the first time anyone has used the internet underwater completely wirelessly.”

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. Then, much like a booster that extends the Wi-Fi range of a household internet router, this gateway sends the data via a light beam to a computer at the surface that is connected to the internet via satellite.

Aqua-Fi will not be available until the researchers overcome several obstacles, with Shihada noting, “We hope to improve the link quality and the transmission range with faster electronic components.” The light beam must also remain perfectly aligned with the receiver in moving waters, and 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,” Shihada concluded. “We hope that one day Aqua-Fi will be as widely used underwater as Wi-Fi is above water.”

Image caption: Scuba divers could send sea life shots in real time using an aquatic internet service. Image ©2020 KAUST/Xavier Pita.

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