ISSUES WITH RF COMMUNICATION
VISIBLE LIGHT COMMUNICATION
PRINCIPLE OF LI-FI TECHNOLOGY
WORKING OF Li-Fi
COMPARISON BETWEEN LI-FI AND WI-FI
“It is a visible light communication system that uses light from light
emitting diodes (LEDs) as a medium to deliver wireless data to PC’s
and mobiles at high-speed in a similar manner as WI-FI”
Radio Spectrum is congested but the demand for wireless data extending
very fastly. Every thing, it seems require wireless data but the capacity is
1.4 Million 5 Billion
• Radio waves.
• cost and expensive.
• Less Bandwidth compared to other spectrums.
• Insufficient Spectrum for increasing data.
• Millions of base stations consume huge energy for
1. Transmitting the radio waves.
2. To cool the base station cabins.
• 5% Efficiency
• Available within the range of Base stations
• Limited availability
• Unavailable in air crafts
• Less Secure (Data can Pass through walls)
WHY VLC ?
• Gama rays,X-rays,Ultraviolet rays are harmful for the human body.
• Infrared rays are also dangerous, due to eye safety regulation, and
can only be used with low power.
• Radio waves are expensive and they are less secure.
• Hence we are left with only the visible - light spectrum which is
not harmful for humans .
X-rays Gama Rays
Principle of LI-FI technology
Heart of Li-Fi technology is high brightness LED’s.
The LED bulb will hold a micro-chip that will do the job of processing the data.
The on/off activity of LEDs enables data transmission using binary codes.
Switching on an LED is a logical ‘1’; switching it off is a logical ‘0’.
A light sensitive device (photo detector) receives the signal
and converts it back into original data.
How Li-Fi Works ?
Li-Fi is implemented using white LED light bulbs at downlink transmitter.
By fast variations of the current, optical output can be made to vary at extremely
An overhead lamp fitted with an LED with signal processing microchip streams
data embedded in its beam at ultra high speeds to the photodiodes.
A receiver dongle then converts the tiny changes in amplitude into an electrical
signal, which is then converted back into a data stream & transmitted to a
computer or mobile device
COMPARISON BETWEEN LI-FI AND WIFI
Sl.No Parameters Light Fidelity Wireless Fidelity
1 Speed for data transfer Faster transfer speed (>1 Gbps) DataTransfer speed (150
2 Medium through which
data transfers occurs
Used Light as a carrier Used Radio spectrum
3 Spectrum Range Visible light spectrum has 10,000
time broad spectrum in
comparison to radio frequency
Radio frequency spectrum
range is less than visible
4 Cost Cheaper thanWi-Fi because free
band doesn’t need license and it
Expensive in comparison to
Li-Fi because its uses radio
5 Network topology Point to point Point to point
6 Operating frequency Hundreds ofTera Hz (THz) 2.4 GHz
• Visible Light is more safe than RF, hence it can be used in
places where RF can't be used such as petrochemical plants.
• Airways communication are performed on the basis of radio waves.
Using communication causes interference between the two systems. To
overcomes this drawback on radio waves , li-fi is introduced.
• Li-Fi emits no electromagnetic interference and so does not interfere with
medical instruments, nor is it interfered with by MRI scanners.
HOSPITAL & HEALTHCARE:
UNDER WATER COMMUNICATION
• Due to strong signal absorption in water, RF use is impractical. Acoustic
waves have extremely low bandwidth and disturb marine life. Li-Fi provides
a solution for short-range communications.
• Street lamps can be used as a source of Li-Fi hotspots
ADVANTAGES OF LI-FI:
Li-Fi removes the limitations that have been put on the user by the Wi-Fi.
Visible light has 10000 times wider bandwidth than radio waves . So, Li-Fi has
got better capacity and also the equipment's are already available.
Data transmission using Li-Fi is very cheap. LED lights consume less energy
and are highly efficient.
There are billions of light bulbs worldwide, they just need to be replaced with
LED’s for proper transmission of data.
Light waves do not penetrate through walls. So, they can‘t be intercepted and misused.
• Interference from external light sources like sun light in the path of transmission
will cause interruption in the communication.
• The light waves cannot penetrate walls.
• This technology was demonstrated and it was detectable up to a distance of 10
• Installation cost of VLC systems are high
• It is easily blocked by somebody simply walking in front of LED source.
As a growing number of people and their many devices access wireless internet,
making it more and more difficult to get a reliable, high-speed signal.
This may solve issues such as the shortage of radio-frequency bandwidth
Every light source in homes and offices could potentially be a “Li-Fi” hotspots
within 20 years.
When this technology becomes feasible like the Wi-Fi, then our life will be
awesome on earth.
“Forget wireless ,get faster internet through light bulbs..!”