Li-FiLi-Fi

Light FidelityLight Fidelity

Post WiFi technology using Visual Light Communication

SRUJAN A,BT10CSE004

What is Li Fi?

● LiFi is an alternative to WiFi that transmits data using Visible Light Communication rather instead of radio frequency waves.

● It is a complement of RF Communication and it solves RF Bandwith limitations.

● In Layman's terms,Li-Fi is transmitting data using actual light bulbs. We can use internet on our device just when the light bulb in our room is switched on.

Life of Li Fi● Professor Harald Haas coined the term Li Fi and is the founder

of this technology, in 2011 TED global talk.

● The promotion of idea through TED helped to start a company pureLiFi.

● PureLiFi, formerly pureVLC, is an original equipment manufacturer firm set up to commercialize Li-Fi products for integration with existing LED-lighting systems.

● In Oct'11, few companies and industry groups formed Li-Fi Consortium to promote this high-speed optical wireless systems.

● LiFi is verified experimentally and also is used in few places already.

LiFi vs WiFi● Both Wi-Fi and Li-Fi transmit data over the electromagnetic

spectrum, but whereas Wi-Fi utilises radio waves, Li-Fi uses visible light. This is a distinct advantage in that the visible light is far more plentiful than the radio spectrum (10,000 times more in fact) and can achieve far greater data density.

● Data receiver using Li-Fi would have to be in sight of the transmitter-bulb as visible light does not penetrate solid materials, which is not the case of Wi Fi.

● Li-Fi is more secure than Wi-Fi with hackers unable to access unsecured internet connections from out of sight of the transmitter.

LiFi vs WiFi

Are Radio waves not fine?

● Capacity: 3G,4G making us running out of spectrum and hence, radio waves are costly. Radio waves are also limited.

● Efficiency: 1.4 million cellular radio base stations each with efficiency of just 5%. Most of the energy is used for cooling down the base station rather than for transmission.

● Security: Radio waves can be transmitted through obstacles and hence viable for security breach. So far, several successful attempts were made in hacking.

● Availability: We cannot use our mobile phones which work with the help of radio waves everywhere. Ex. To be switched off in aircrafts.

Why only Visible Light?

● Gamma rays are dangerous for communication.

● X-rays can't be used for communication as they are to be used in controlled environment and is costly.

● Ultravoilet rays are useful for skin to some extent but when used for communication for long time, they are dangerous.

● Infrared rays are to be used at low power levels as their effects on human eye.

● Radio waves shortcomings have been discussed earlier.

● Visible light has no above mentioned issues,is safe for human and is faster.

How does LiFi work?

● On one end all the data on the internet will be streamed to a lamp driver.

● When the LED is turned on the microchip converts this digital data in the form of light.

● On the other end this light is detected by photo sensitive devices.

● Next this light is amplified and processed and then fed to the device.

● The heart of this technology is a new generation high brightness led’s.

● These led’s varies in intensity (that is gets on and off) so fast that a human eye cannot detect it.

● If led is on , then we transmit a digital signal 1,and if the led is off , then we transmit a digital signal 0.

● A controller is connected at the back side of these led bulbs to code data to these leds.

Li Fi construction

The LiFi product consists of 4 primary sub-assemblies:

1. The high concentration of energy in the electric field vaporizes the contents of the BULB to a plasma state at the bulb’s center; this controlled plasma generates an intense source of light.

2. The Printed Circuit Board (PCB) controls the electrical inputs and outputs of the lamp and houses the microcontroller used to manage different lamp functions.

3. An RF (radio-frequency) signal is generated by the solid-state PA and is guided into an electric field about the bulb.

4. All of these sub-assemblies are contained in an aluminum enclosure.

Illustration

Is it just theoritical?● No, Herald had successfully demonstrated it using a table lamp.

● The first Li-Fi smartphone prototype was presented at the Consumer Electronics Show in Las Vegas from January 7–10 in 2014. The phone uses CONNECT, a technique that converts light waves into usable energy, making the phone capable of receiving and decoding signals without drawing on its battery.A clear thin layer of crystal glass can be added to small screens like watches and smartphones that make them solar powered. Smartphones could gain 15% more battery life during a typical day. This first smartphones using this technology should arrive in 2015. This screen can also work to receive Li-Fi signals and so can the smartphone camera.The cost of these screens per smartphone is between $2 and $3, much cheaper than most new technologies.

● Philips lighting company has developed a Li-Fi system for shoppers at stores. They have to download an app on their smartphone and then their smartphone works with the LEDs in the store. The LEDs can pinpoint where they are at in the store and give them corresponding coupons and information based on where aisle they are on and what they are looking at.

● The technology is ready right now. It's being installed in museums and businesses across France, and is being embraced by EDF, one of the nation's largest utilities.

Where can it be used?

● Everywhere in every field as we use Visible light extensively including hospitals,aircrafts,etc without bothering about any harm.

● It can be used in home, office, businesses, museums, etc which can be used as light, security and data transmission as well.

● It can be used in traffic control (pic demonstrated.)

● Having them on street lights takes the internet usage to a higher level.

Traffic Control

Limitations

● There should be line of sight between sender and receiver (This has been proved to be not necessary experimentally but yet to verify in daily life)

● Visible light cannot penetrate through solid objects

● Interference with other electromagnetic waves makes the transmitting data to distort.

● Light cannot approach the range of radio waves

● A major challenge facing Li-Fi is how the receiving device will transmit back to transmitter.

● Interferences from external light sources like sun light, normal bulbs, and opaque materials in the path of transmission will cause interruption in the communication.

Open for Questions & Discussion