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Li-Fi Technology in the U.S. Navy

Does the Newest Transmitting Tool Have a Place in our Fleet?

by Mass Communication Specialist 2nd Class Taylor Stinson, Defense Media Activity
09 January 2019 Whether Sailors are aviation maintenance administrationmen documenting maintenance before an inspection or machinist mates looking up standard operating procedures for preventative maintenance on equipment in the main engine, a common problem they face aboard ships is the lack of access to a computer during crunch time.
VIRIN: 190108-N-TP976-001

But what if it were possible to look up information or exchange maintenance documents and data within the ship's network without actually needing to use a desktop or laptop? Li-Fi (“light fidelity”) technology could make it possible for any Sailor to complete his or her daily tasks via a tablet or hand-held device, without waiting in the queue for the next desktop machine.

Li-Fi is a light-based communication technology that uses light instead of radio waves to deliver data. It is a high-speed network communication protocol that is similar to Wi-Fi, but is capable of speeds up to 10 times faster. Li-Fi uses a signal-processing element to convert data into binary light signals and a photo-detector to receive signals. In other words, data is converted to light signals and transmitted by an LED light bulb that sends the data at rapid speeds to the photo-detector. The signal is then converted back into a binary data stream that would be recognized as web, video and audio applications running on Wi-Fi enabled devices.

In theory, this would provide the U.S. Navy with the ability to have an internal wireless broadcast network that could be used with personal tablet devices. Sailors would be able to use the tablets for everyday functions, such as connecting to maintenance servers or uploading paperwork without actually having to rely upon a desktop computer.

Besides transmitting data at faster speeds, Li-Fi is also superior in terms of security. Since Li-Fi accomplishes its wireless data exchange by using signals in the visible light spectrum, its data signals cannot be intercepted by receiving devices outside the skin of the ship because light cannot travel through walls — especially steel bulkheads. This is different from Wi-Fi, based on radio-frequency radiation, which penetrates solid objects and is therefore at risk of interception from outside the ship.

The Office of Naval Research is also working with firms to develop the Tactical Line-of-Sight Optical Network (TALON), which would use Li-Fi for ship-to-ship and ship-to-shore communication. The system has the potential to fill gaps in the U.S. Navy's communication infrastructure, specifically with the transfer of intelligence, surveillance and reconnaissance (ISR) data. However, the new technology still faces some limitations.

“The overall limitation is that it's short-ranged,” said Carlton Harris, chief of cyber technologies and experimentation at the Defense Information Systems Agency (DISA). “It only communicates as far as 10 meters, whereas Wi-Fi can communicate up to about 30 meters away. In my view, interference is another potential limitation. For example, if someone can block the light, then the communication will stop. ... Lastly, although it has the potential to be cheaper, to convert [from older technologies] and implement this [new] technology will initially be at a high cost.”

Space and Naval Warfare Systems Command (SPAWAR) has also recently worked with the John Hopkins University Applied Physics Laboratory (APL) to evaluate Li-Fi. The capability was tested aboard USS Carl Vinson (CVN 70), in coordination with more than 20 other Navy platforms, during Trident Warrior 2018 in August.

“The Navy wanted to see what the effects of shock and vibration would be on the wireless link and the equipment,” explained APL communications engineer Ryan Mennecke, who, along with APL's Eddie Holzinger, led the Li-Fi experiments. “We designed and manufactured custom mounts to install commercial Li-Fi equipment with the library of the aircraft carrier, which is located underneath catapult three. The test included setting up a standalone network to stream live video and collect test data off the optical link. ... The system performed flawlessly.”

While it may take a long time before Sailors begin to see Li-Fi capabilities aboard ships, the possibilities for the future are very real.