Without light, nothing would exist; literally. Light is the thing that makes life possible and it is the thing that enables us to be able to see and interpret the world around us. Light has also been a key way that humans have sent messages, going as far back as the Ancient Greeks, who used a coded system of signalling with torches.

Modern communication is the result of humans learning how to utilise radio waves, an invisible form of light, to transmit data. Now however, scientists and technologists are wanting to use physical lights to help provide a low cost alternative to Wi-Fi.

First developed by a team led by Harold Haas, light fidelity (Li-Fi) is a ‘bi-directional, high speed and fully networked wireless communication system’ that uses LED bulbs to transmit data. The technology works by pulsing LED lights, imperceptible to the human eye, to enable data transfer.

Earlier this year, researchers from the University of Oxford used Li-Fi to achieve speeds of 224 Gbps. According to the researchers, this would enable 18 movies of 1.5GB to be downloaded in a single second.

Part of the idea behind Li-Fi, as an alternative to Wi-Fi, is the fact that we have 14 billion light bulbs across the world and that as a result, the infrastructure is largely there. Admittedly, for it to become a reality would require for 14 billion Li-Fi bulbs to be deployed.

According to Haas, Li-Fi is also meant to be more secure than traditional Wi-Fi networks; as the light needs to be directly visible. For example, unless your phone was in the room where the Li-Fi bulbs are and out on a desk or in a hand, it wouldn’t be able to connect to the data.

Li-Fi builds on a similar use of light for high-speed data transfer, free space optics. First developed by NASA during the Apollo programme, free space optics uses lasers to provide network communications. Still used today to provide a secure link between buildings in cities and at military bases, free space optic systems are capable of delivering speeds of around 10Gbps.

Last year, Philips introduced a system using LED lights in a retail store to deliver a beacon like experience to mobile users. The system, which uses a downloadable app and the smartphone front camera to detect Visual Light Communications (VLC) to transmit data.

Unlike beacons, where the app is able to listen in the background, using VLC would require users to have their phones out to be able to take advantage of the connected retail lighting system. This has some clear benefits when it comes to user opt in and user privacy; though could also raise privacy concerns about the front camera being active.

We’re still a long way away from Li-Fi becoming a reality or even understanding whether it is commercially viable. The most likely scenario is that Li-Fi will be used for the smart home or smart office applications, where security is more important to securely connect with things.

At the end of the day, all of this technology is building on the same principles of using the light spectrum to transmit data — which is precisely how mobile data, Wi-Fi and Bluetooth works already. Understanding how light, and the light spectrum, works is what makes the modern world possible. As we continue to hone it and use it to our advantage, we’re able to push the boundaries of speed and open up new ways to innovate with technology.

Light Fidelity

source: Wikipedia

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