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LiFi- Light Fidelity


What does LiFi mean?

Light Fidelity (LiFi) is a wireless optical networking technology that uses visible light from LED for data transmission. Unlike infrared-based systems, Visible Light Communication involves transmitting data using light visible to the human eye.

LiFi has been designed to use LED light bulbs similar to those currently in use in many energy-conscious homes and offices. However, LiFi bulbs are outfitted with a chip that modulates the light imperceptibly for optical data transmission. LiFi data is transmitted by the LED bulbs and received by photoreceptors.


Benefits of LiFi:-

  • Higher speeds than Wi-Fi.

  • 10000 times the frequency spectrum of radio.

  • More secure because data cannot be intercepted without a clear line of sight.

  • Prevents piggybacking.

  • Eliminates neighboring network interference.

  • Unimpeded by radio interference.

  • Does not create interference in sensitive electronics, making it better for use in environments like hospitals and aircraft.

  • Using LiFi in all the lights in and around a building, the technology could enable a greater area of coverage than a single WiFi router.

How LiFi works-

LiFi uses visible light as a medium for the transmission of data. As a type of VLC system, it requires two components a photodiode and a light source. The photodiode acts as a transceiver that receives light signals and transmits them back. The light source transmits data using emitted light as the medium. In this case, light-emitting diodes (LED) serve as the light source. They are outfitted with a chip that serves as the signal processing unit.

LED light bulbs are semiconductors. This means current supplied to the bulb can be modulated, which in turn, modulates the light they emit. This process occurs at extremely high speeds that are unperceivable to the human eye. Data is fed into the light bulb and sends the data at extremely high speeds to the photodiode. It converts the data received into a binary data stream perceivable by humans such as video and audio applications.


How data is transmitted over light?

To send data using light, LiFi systems require a robust light source like LED bulbs. LEDs are different from halogen or filament bulbs as they do not need to warm up. As previously stated, they are semiconductors. They start up quickly and emit light according to the current passed through them.

Within the light, the intensity of the colors red, green, and blue (RGB) is finely modulated to embed data into the LED light. (this process is undetectable to the naked eye) This fine modulation of RGB can be described as a form of code. Once the light is received by a photodiode, the light is demodulated. The information received is either relayed to a cloud server or transcribed by the receiver itself. Content is then displayed according to the code obtained.

Can we see LiFi lights flicker?

The LED lights used to transmit LiFi signals are modulated at such a fast rate that the eye cannot perceive the modulation or flicker. This is similar to the way our eyes do not interpret the break between film frames in a motion picture. Just as you see a smooth motion on the cinema screen, you will see an uninterrupted source of steady light streaming from a LiFi enabled luminaire.

As a comparison, the lowest frequency at which the lights are modulated is 1MHz and this is 10,000 times higher than the refresh rate of our computer screens.

How does LiFi work when you turn off the lights?

If all power to lights is turned off then there is no LiFi. However, LiFi technology can be enabled to dim low enough that a room will appear dark and still transmit data. There is a consistent performance between 10 and 90 percent illumination.

Currently, pureLiFi’s technology provides communications at light levels down to 60 lux. For comparison, the British standard for minimum light level for reading is 400 lux.

There are also other options for using invisible parts of the light spectrum such as infra-red, which is currently already being used for sending information back to the light bulb (uplink).


Is LiFi a line of sight technology?

Light bounces off of surfaces and therefore LiFi is not strictly a line-of-sight technology.

LiFi is a cellular communication system and the data rate is not dependent on the line of sight but the signal quality at the device. Signal quality can be defined by the ratio of the desired data vs any interfering data and noise.

Will LiFi work in my pocket?

No LiFi does not work in your pocket unless you have a transparent suit.

LiFi is a complementary technology that works alongside other wireless technologies such as Wi-Fi. If the light signal to a LiFi enabled device is below the receiver’s threshold then it will not receive data. In that instance, radio systems or cellular networks, if available, will continue to deliver data.

However, the moment the device begins to receive light from a LiFi light bulb, the device will resume high-speed communications using light as an additional communications medium.

Advantages of LiFi:-

  • Speed: The biggest selling point of LiFi technology is that it can transmit data at far greater speeds than WiFi. During lab tests, researchers were able to reach bidirectional transfer speeds of 224 gigabits per second. Of course, it would be difficult to reach those speeds in a real-world setting. But reaching even 1% of that means speeds of 2.24 gigabits per second – a significant improvement over WiFi, which nets transfer speeds of about 20 megabits per second.

  • Versatility: With the current operational concepts of LiFi, its experimental applications center on the use of LED bulbs and lamps. Hence, it is easily integrated into areas that already use LED lighting systems. The internet is readily-accessible wherever there is light and can be used in a variety of applications that require an internet connection.

  • Cost: Because LED lamps are inexpensive to produce, analysts predict that the deployment of LiFi would be easier and ten times cheaper than WiFi. They are also more energy-efficient than any other lighting technology. As LiFi systems operate to provide illumination and for internet connectivity, so you save up on energy costs.

  • Availability: As the world looks to use green technology, LED light bulbs are becoming a staple everywhere – in homes, offices, businesses, and even transportation. This means soon enough, high-speed internet connectivity will be as ubiquitous as there are light bulbs.

  • Security: RF communication technology has always been vulnerable to eavesdropping, signal hijacking, or even brute force attacks. However, visible light is unable to permeate opaque surfaces. Signals emitted by LiFi as well as the data transmitted through it remain confined within the space.

Disadvantages of LiFi:-

  • Range: LiFi offers a limited range. While this may prove useful for security, it also creates disadvantages. Physical barriers limit its operational scope. To increase its scope, lamps or bulbs must be strategically placed in various rooms. In contrast, a single WiFi router has a wider, longer range, making them an ideal selection for public networks.

  • Interference: LiFi signals are susceptible to light interferences, including sunlight. Receivers may have a difficult time processing signals when other sources of light are present. Moreover, because LED lamps must remain on to function, they can further contribute to light pollution, especially if set at higher brightness levels to compensate for possible interference.

  • Infrastructure: Theoretically speaking, deploying LiFi systems is inexpensive because they only make use of LED lamps. In reality, the installation of LiFi systems can become expensive due to the lack of infrastructure. Additionally, due to its limited range, several LiFi routers will need to be installed for greater connectivity. This means incurring additional purchase and installation costs. In contrast, a small home will only require a single WiFi router.


Applications of LiFi:-

  • Traffic Management & Road Safety

Vehicles can get information that another vehicle is coming from front or back with this much speed. It can be used to give collision warning and can even be used in smart automatic braking systems in smart driving cars. This will stop 80% of the road accidents to happen.

  • Aviation Sector

The usage of LiFi in airplanes will not affect other communications. Other communications rely on radio waves. Visible light will not interfere with RF to disturb the signals. Every reading light above each seat in flight can also give high-speed internet access along with the light.

  • Smart Advertisements

Just think about the time when you are passing by a store and amazing deals and offers pops up on your mobile screen for that shop. Yes, LiFi can make is easily possible. Shopkeepers will be able to use LiFi enabled LED Bulbs that will emit a static message continuously.

  • Underwater Applications

As most of the remote-controlled underwater vehicles or ROVs are operated with the help of wired connections, there is always a limitation of range and other potential factors. The cables are also costly. LiFi can be used there to provide an economic and efficient solution. This is because light can travel under the water.



Differences between Li-Fi & WiFi:-

  • The Bandwidth Expansion of Wi-Fi technology is limited and exceptional for Li-Fi

  • The Speed of the Wi-Fi is150 Mbps and >10 Gbps for Li-Fi

  • The Data Density of Wi-Fi technology is low and high for Li-Fi

  • The Range of Wi-Fi is medium and low for Li-Fi

  • The Security of Wi-Fi is medium and excellent for Li-Fi

  • The power availability of Wi-Fi is low and high for Li-Fi

  • The ecological impact of Wi-Fi is medium and low for Li-Fi

  • The cost of the Wi-Fi is medium and low for Li-Fi

  • The network topologies of Li-Fi and Wi-Fi technologies is a point to point


Conclusion:

Light fidelity technology is indeed the future of internet connectivity. Scientists are exploring various options to make this technology available to households and shortly we will see the day where LED bulbs would be working as data transmitters and you would be downloading your favorite movies and web series in just a few minutes.




Written by

Shubham Rattra

University Institute of Engineering and Technology, Panjab University

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