Li-fi is a way of transmitting data – including the internet – to devices such as smart phones using visible light from LEDs pulsed at high frequency.
The new luminaire – developed by Scottish start-up pureLiFi and French light fitting manufacturer Lucibel – places all the necessary Li-Fi components in a black ring that lies flat against the ceiling and is designed to circle an LED light. It is able to support between eight to 16 users at once, and deliver data at rates of 45 megabits per second.
How does it work?
It's bi-directional, unlike so-called visual light communication, or VLC, in which information is broadcast in one direction to devices.
The lights are pulsed at extremely high frequencies which is undetectable to the human eye. It operates at many hundreds of times faster than high-frequency lighting power supplies or ballasts which are used today.
Devices can download information in two ways:
It can use the forward-facing camera on your smart phone or laptop. In truth, the components required to deploy this technology are much simpler than Wi-fi or Bluetooth. Think about how many devices already have some sort of light-sensing capability to enable functions such as automatic screen dimming.
Alternatively, a plug-in dongle with built-in photo-receptor receives the information.
The luminaire transmitting the data still needs to connect to the internet or network. This could be with an Ethernet connection or using power-line communication, which is basically data sent over conventional mains wiring. Li-fi engineers say the best solution is to have the whole installation as a Power over Ethernet installation, where both power and data is sent along Cat 5 or Cat 6 cables.