Visible light communication (VLC) using light-emitting diodes (LEDs) is being developed to overcome spectrum congestion issues with the proliferation of internet-connected devices using radio frequency (RF) signals. VLC uses the visible light spectrum, which has 10,000 times more capacity than the RF spectrum. Li-Fi, demonstrated in 2011, transmits data through visible light modulation at speeds up to 10 Gbps. VLC allows for high-speed secure data transfer over short ranges using existing LED lights and additional photodiodes in devices. It has potential applications for device-to-device communication and high-security authentication through instant data transfer.

2.  Smart devices everywhere – 26 billion
devices will be in IoT by 2020.
 RF spectrum is congested and new
devices will cause more interference
Cisco mobile data forecast
1𝐸𝐵 = 10006 bytes

3.  To overcome this spectrum issue, Visible
Light Communication (VLC) is being
developed.
 The spectrum of Visible light is 10,000 times
more than the spectrum of RF.
 The data transfer rate of VLC is very high.
 Li Fi – an VLC technology demonstrated by
Dr. Harald Haas in 2011

4. Visible Light Spectrum 430 THz to 790 THz
RF spectrum 3 KHz to 300GHz

5.  Transmits data using light. LED is used as
transmitter.
 High data rates achieved with DC biased
Optical (DCO) OFDM and Spatial Modulation
techniques.
 Intensity of light modulated at high rate.
 10 Gbps Li Fi prototype tested by Sisoft in
2014

6.  Fujitsu Laboratories developed a model to
replace QR code scanning with Li Fi
technology.
 Philips successfully used Li Fi to create
shopping assistant.
In both cases, Fixed LEDs transmits data.
Smart phone camera used as receiver. So low
bit rate data transfer.

8. One Smart device to another data transfer
- all devices will have both transmitter and
receiver. LED flash in device can be transmitter.
Photodiode has to be added additionally
- photo diode & High data rate LED will make
short range high data transfer.(up to 200 Mbps)
Flash transfer- make use of LED flash to
transmit huge data unidirectional.

9. Transmitter – Commercial Phosphor
based white LED
Receiver- low cost photodiode; single
photodiode with 1.2Gbps used in OFC.
Customized diode for VLC economically
Signal Processing module
Almost analogous to 4G LTE.
Therefore, with latest technology chip size
in Nano meters

11.  Large bandwidth – around 100 MHz here
 High Data rate
 Secure connection – user can see the range &
light won’t penetrate wall
 No delay for connection as there will be no
need for authentication
 No harmful radiation

12.  Almost Line of Sight transmission
 Short distance – up to 1 m since the use of
single low power LED
 Two way Li Fi connection is not viable – at an
instant device can either send or receive data
simplex transmission

13.  High speed wireless device to device data
transfer
 It can transmit large information instantly. So
it can be used as high security pass - a set of
(can be billion) security codes.
This type of authentication can be used at
 ATM
 Secured Places and
 Secured internet connection/ computer

14. Future role of Light
Under Internet of Everything, VLC will play
a vital role. LED lighting is being increased due
to its efficiency.
Our proposed idea will be available in all
smart devices in a decade.
Already Optical communication is backbone
in the form of OFC. Like our proposed short
range communications may create all optical
network.