Problems with Wi-Fi? Turn on the… light!
Not to get a good idea, but because, in the future, a simple LED will be enough to connect to the web with computers, tablets, and smartphones: it is the revolution promised by Li-Fi.
What is Li-Fi?
Li-Fi stands for Light Fidelity and is a term first introduced by Harald Haas in a speech at TED Global in 2011, referring to the optical Wi-Fi (Wireless Fidelity).
In this connection system, the frequencies occupied for the exchange of communications belong to the spectrum of visible light, with interesting advantages compared to radio transmissions.
We can, therefore, define Li-Fi as a light Wi-Fi that will allow the fast transmission of large amounts of data, while at the same time guaranteeing greater protection of communications. The operation of the Li-Fi is explained to us by Michele D’Amico, professor of Wireless and Mobile Propagation at the Politecnico di Milano, in the new video post of #IlPOLIMIrisponde: “Both Li-Fi and Wi-Fi use electromagnetic waves for transmitting data at high speed: while Wi-Fi uses radio waves, the Li-Fi uses electromagnetic waves in the visible band” of light, therefore.
For the connection, an LED lamp is all we need: “Unlike traditional incandescent or fluorescent lamps,” continues D’Amico “the LED lamp has a brightness that can be changed extremely quickly and imperceptibly to the human eye”.
The visible light modulated at very high speed, therefore, is able to transmit data to the user’s terminal, equipped with a photodetector, aka a photodiode that transforms the brightness variations of the LED into electrical signals.
The advantages of Li-Fi
Thanks to the Li-Fi there will be no conflict with the radio transmission, in the event of interference due to the occupation of the same frequency. So, the absence of radio interference makes it suitable for use in hospitals and airplanes, eliminating the related safety problems.
Furthermore, as the signal is limited to the optical range, the interception of communications will be more difficult and it will be possible to create large transmitters with much higher energy efficiency than radio stations.
Harald Haas himself, again on the occasion of the presentation at TED, demonstrated how to modulate the frequencies used by the LEDs of a normal light bulb to transmit a video in high definition.
The limits of this new connection technology
Among the limitations of this new technology, unfortunately, there is precisely the optical range: “The Li-Fi does not overcome opaque obstacles and walls and it is, therefore, necessary to install a terminal in every environment that you want to connect to the network.” D’Amico said, “It also requires that the lights must always stay on, even during the day”.
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