Wi-Fi is heading towards Li-Fi. And the armed forces are waiting on the road

What is Li-Fi?

Today we live in a world of Wi-Fi (Wireless Fidelity). Some very popular terminals, such as cell phones, as well as other devices use wireless networks to reach various services or facilitate communications. Despite all this, we must recognize that Wi-Fi is starting to be limited for what we, the users, or communications service providers desire.

Li-Fi (Light Fidelity) technology is one of the options proposed as a new form of data transmission. But what is Li-Fi? The term “Li-Fi” was used for the first time in 2011 by engineer Harald Hass, during a TED conference at the University of Edinburgh. The technology consists of a data transmission technique which makes use of visible light, as well as ultraviolet and infrared lights to achieve communication. More specifically, if we think of the popular LED lights, it is estimated that they could be switched on an off approximately 10 billion times per second (which people could not be able to perceive). With this capacity, “on and off” could be translated into binary language, and could thus be capable of reaching speeds of 10 Gbps.

The connection is made through two LEDs, like in the case of TV remote controls. One of the LEDs will send light signal which cannot be perceived by the human eye, while the other will receive them. This means that all the electronic devices capable of Li-Fi connection will have to be adapted in order to be capable of “translating” luminous impulses, as is the case with Wi-Fi technology. Taking into account the fact that the signal transmitter can be adapted for infrared lighting, the connections will be achievable in the dark, without that spectrum being observable in the absence of special equipment.

The characteristics of Li-Fi technology

This new technology has, according to specialists, both advantages and disadvantages. We called them characteristics, because some of the disadvantages mentioned could become advantages I the technology will be used in the field of defence or security:

• The first characteristic refers to reaching a superior data transmission speed when compared with Wi-Fi. As we have already mentioned, the transmission speed could move in the 10-20 Gbps interval, and maybe even more (some tests reaching up to 224 Gbps);
• Energy consumption could be reduced with the help of already available LED illumination. Data transmission requires a negligible amount of additional power, which makes this technology very cost and energy efficient;
• Li-Fi connections could be achieved in places sensible to electromagnetic zones, such as aircrafts, hospitals where the use of Wi-Fi technology is either not accepted or accepted in a limited capacity;
• Availability is another characteristic, as light sources are present almost anywhere, in houses, bureaus, stores, on the streets. Li-Fi can be used wherever a lighting sources exists;
• While the electromagnetic spectrum used by Wi-Fi technology risks reaching its saturation point, the visible light spectrum (10,000 times larger) offers multiple possibilities;
• Light bandwidths are relatively small, which means that the connection will be limited by the distance between transmitter and receiver. In the case of Li-Fi, the distance between a transmitter and a receiver is way smaller than in the case of Wi-Fi;
• Li-Fi can be generated in the visible light spectrum, as well as in the one invisible to the human eye;
• Light cannot travel through opaque obstacles. For this reason, the use of this technology is limited to the rooms where the light signal is directly transmitted;
• Direct visibility between the transmitter and receiver is required. Even if walls can reflect light, the connection’s speed would drop significantly. We can say that Li-Fi works better in enclosed areas, which could eliminate the need to secure the network or to use log-in passwords;
• Light travels through non-opaque obstacles (such as windows). This raises a question: will we need to cover our windows every time we use the connection in order to avoid our neighbour from connecting? This will be answered by the technology’s future developments.
• Sunlight could affect the network. At the same time, another source could disturb connections achieved with this technology.

The military use of Light Fidelity

The main advantage of using Li-Fi technology is the capacity to ensure data and operations security, because light cannot travel through walls and other opaque surfaces.

In June 2018, the French Army held a contest, through the Army’s Technical Section, destined for developing Li-Fi equipment. French LED illumination and innovation company Lucibel won the competition, and was invited to collaborate to the project and take part to the Defence Sector Innovation Forum in November 2018. During the event, the said company presented its “Lucibel Li-Fi Solution”.

In July 2018, British Telecommunications (BT) Defense worked with PureLifi in order to test Li-Fi in a park (open area) and discovered that they could apply several layers of security for users or groups of users, achieving a virtual delimitation of a geographical area – or geofencing.

In November 2018, the US Army’s Research, Development and Engineering Command made a study on the use of Li-Fi in an operational command point. The study researched the ways in which commercial technology can be used in a tactical environment to achieve wired or wireless connections. Frank Murphy, an engineer in the EMSD’s Projects and Development team, stated that a “command point, regardless of its size, is a place where information is processed”. Following the study, it was concluded that the use of Li-Fi in a command post ensures data security, because opponents cannot passively listen to Li-Fi as is possible with radio frequencies, and can neither scramble nor alter radar information. Li-Fi also ensures the capacity for long-distance communications, such as those between command points or ships.

The study also showed the following aspects:

• Li-Fi technology can be used for conferences or classified briefings, held in a video or audio-conference system;
• The time necessary to set up computers in the command point network is significantly lower, due to the use of pre-set USB type receptors. This facility also increases the install-uninstall speed, as well the tactical manoeuvring of a command point;
• It allows communications in environments with increased risks of explosions, because it does not use the electromagnetic field;
• It reduces the electromagnetic print of command points;
• It can be used in environments where Wi-Fi cannot transmit, such as within bunker walls or the metallic structure of warships.

Conclusions… which anticipate solutions

For the moment, test results are not up to expectations, for researchers in the field are tirelessly working to improve this technology. Phillips can boast with the fact that it developed this type of connection, but cannot boast with the speed of its internet. In the office where it was tested, Li-Fi ensured an internet connection of only 30 Mbps.

Despite all this, as the necessity for faster and more secure communications increases, Li-Fi could be seen as one of the solutions. Obviously, there is a multitude of possibilities to use the Li-Fi technology in the military field, but this technology is still very new at the moment, and has numerous problems to overcome before it gains the interest of major defence industry developers.

The recent demonstrations made by Astronics in October 2018 and at the Air France Expo in June 2019 show some progresses and promising investments, but it is unlikely that this technology will be used on a large scale in the near future. However, the armed forces in developed states maintain their interest for the development of this technology, which could bring them an operational advantage within the following 10 or 15 years.

Translated by Ionut Preda