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LiFi Explained in 2 Minutes !!

posted Sep 2, 2017, 2:09 AM by Rohit Bhaskar   [ updated Sep 2, 2017, 2:14 AM ]

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Every imagined yourself returning home after a tedious work day (maybe from office or after attending 6-7 hours lectures in college, assignment submissions, labs and what not…) and then switching on your room’s light and Boom!! You get connected to an extremely high speed internet connection. (no, we aren’t talking about magic ;P)

Think of yourself using an internet connection, which is 100x times faster than what the existing Wi-Fi system offers (I hope that you must have used Wi-Fi at your home/office/college or at least at your friend’s house) 


... Umm… seems impossible....right? 


No! It’s definitely possible and the technology that turns this into reality is Li-Fi (Light Fidelity). The term Li-Fi refers to light based communications technology that delivers a high-speed, bidirectional, networked and mobile communications in a similar manner as Wi-Fi.


Prof. Harald Haas, coined the term "Li-Fi" at his 2011 TED Global Talk where he introduced the idea of "Wireless data from every light". Li-Fi uses visible light to transmit signals wirelessly and is an emerging technology poised to compete with Wi-Fi. It is 100x times faster than the Wi-Fi (mentioned it twice because even I didn’t believe it at first). 


So How Does Li-Fi Work? 


Li-Fi is a Visible Light Communications (VLC) system for data transmission. A simple VLC system has two main components: 

At least one device with a photodiode (photo detector) which is able to receive light signals.

A light source equipped with a signal processing unit (Lamp Driver).

A VLC light source could comprise of a fluorescent or light emitting diode (LED) bulb. Since a robust Li-Fi system requires extremely high rates of light output, LED bulbs are most ideal for implementing Li-Fi. LED is a semiconductor light source, which implies that LED light bulbs can amplify light intensity and switch on/off rapidly. Therefore, LED cells can modulate thousands of signals per second without the human eye ever noticing. In turn, the changes in light intensity from the LED light source are interpreted and converted as electrical current by the receiving photodiode device. Once the electronic signal is demodulated, it is converted into a continuous stream of binary data comprising of audio, video, web, and application information to be consumed by any Internet-enabled device.

You can find video of its working  below. (Do watch it…)




What’s the difference between Li-Fi and Wi-Fi?

So the basic difference lies in the way the data is being transmitted. To be technical, Wi-Fi uses the Radio wave bandwidth of the electromagnetic spectrum whereas Li-Fi uses the visible wave bandwidth of the electromagnetic spectrum to transfer data. The frequency range for Radio wave is 3kHz - 300 GHz and for the visible light it is 400 THz - 800 THz. The frequency spectrum of these two waves reveal the fact that visible light frequency (in THz) is 1000 times more than the radio wave frequency (in GHz) and hence the reason to achieve high speed data transmission rates.

The transmission of data in case of Li-Fi is done through rapid switching on/off of LEDs i.e. changing the intensity of light (human eye cannot see the rapid switching phenomenon), whereas in case of Wi-Fi, the data is transmitted via modulation of data signals on to radio signals and then demodulating it at the receiver’s end.


Advantages of Li-Fi technology:

Efficiency: Li-Fi works on visible light technology. Since homes and offices already have LED bulbs for lighting purposes, the same source of light can be used to transmit data. Hence, it is very efficient in terms of costs as well as energy. Light must be on to transmit data, so when there is no need for light, it can be reduced to a point where it appears off to human eye, but is actually still on and working.

Availability: Wherever there is a light source, there can be Internet. Light bulbs are present everywhere – in homes, offices, shops, malls and even planes, meaning that high-speed data transmission could be available everywhere.

Security: One main advantage of Li-Fi is security. Since light cannot pass through opaque structures, Li-Fi Internet is available only to the users within a room and cannot be breached by users in other rooms or buildings. (So, now you won’t have to share password with your friends. @@)


Disadvantages of Li-Fi technology:

Internet cannot be used without a light source. This could limit the locations and situations in which Li-Fi could be used.

Because it uses visible light, and light cannot penetrate walls, the signal's range is limited by physical barriers.

Other sources of light may interfere with the signal. One of the biggest potential drawbacks is the interception of signals outdoors. Sunlight will interfere the signals, resulting in interrupted Internet.

A whole new infrastructure for Li-Fi would need to be constructed.


But it's not all doom and gloom! Due to its impressive speeds, Li-Fi could make a huge impact on the internet of things too, with data transferred at much higher levels with even more devices able to connect to one another.

Recent experiments carried out have showed impressive results of achieving 100 Gbps with laser LEDs. 

The Li-Fi products are already out in the market. You can find more information about Li-Fi technology and its products online.

I know it was reeeally long post, but that’s all for today!! Hope you understood what LiFi is :)



- Rajneesh Katkam
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