LI-FI TECHNOLOGY

Introduction to Li-Fi:

  Li-Fi is the abbreviation of light fidelity and was expressed by Harald Hass who was a German physicist. In Li-Fi the information is transferred through light signals instead of radio waves and mostly Wi-Fi plays an efficient role for wireless information coverage within the buildings whereas by using Li-Fi we can provide the excel density data coverage in a particular area without any radio interference issue. It furnishes well bandwidth, assurance than Wi-Fi and excels speed. In the coming generation, this technology will be used for transmitting data or information to smartphones, laptops etc. through the light in a room.

The affordable, speed change in the optical form of Wi-Fi is the Li-Fi and it is based on VLC i.e. Visible Light Communication where VLC is a medium of information communication which avails quick pulses of light to send the data wirelessly. The main constituents of a Li-Fi system are:

• An excel brightening white LED which plays the role of a transmitter.
• A silicon photodiode with a good response to visible light acts as a receiver.

LED’s can be switched on and off through which different unions of digital chains consisting of 1’s and 0’s are produced. The LED can be used as a transmitter or a source, the response of LED appears consistent to the human eye due to the quick flickering of LED.

Working of Li-Fi:

In a typical setup, the transmitter (LED) is connected to the data network (Internet through the modem) and the receiver (photo detector/light sensor) on the receiving end receives the data as light signal and decodes the information, which is then displayed on the device connected to the receiver. The receiver (photo detector) registers a binary ‘1’ when the transmitter (LED) is ON and a binary ‘0’ when the transmitter (LED) is OFF. Thus flashing the LED numerous times or using an array of LEDs (perhaps of a few different colours) will eventually provide data rates in the range of hundreds of Mbps. The Li-Fi working is explained in a block diagram.

Hence all that is required, is some or an array of LEDs and a controller that controls/encodes data into those LEDs.All one has to do is to vary the rate at which the LEDs flicker depending upon the data input to LEDs. Further data rate enhancements can be made in this method, by using array of the LEDs for parallel data transmission, or using mixtures of red , green and blue LEDs to alter the light’sfrequency, with each frequency encoding a different data channel. Figure 7 shows working/deployment of a Li-Fi system connecting the devices in a room.

*History:

     Li-Fi technology was first introduced by a German professor,physist and communications technology innovator, Herald Hass, at a TED talk in july 2011.in his talk, Herald demonstrated how energy can be transmitted from a light bulb by inducing subtle changes in the amplitude of the light bulb in such high speed that they are not visible to the human eye. Herald demonstrated Li-Fi to audience by playing a high definition vedio of a flower that was solely transmitted using a LED table lamp with an LED bulb.

Today, Li-Fi has been deployed in more than 20 countries.

* Comparison Between Li-Fi and, Wi-Fi and other Radio Communication technologies Both Wi-Fi and Li-Fi:

    can provide wireless Internet access to users, and both the technologies transmit data over electromagnetic spectrum. Li-Fi is a visible light communication technology useful to obtain high speed wireless communication. The difference is: Wi-Fi technology uses radio waves for transmission, whereas Li-Fi utilizes light waves. Wi-Fi works well for general wireless coverage within building/campus/compound, and Li-Fi is ideal for high density wireless data coverage inside a confined area or room and is free from interference issues unlike the Wi-Fi. Table I shows a comparison of transfer speed of various wireless technologies. Table II shows a comparison of Li-Fi with Wi-Fi.

*Advantages of Li-Fi :

Li-Fi, which uses visible light to transmit signals wirelessly, is an emerging technology poised to compete with Wi-Fi. Also, Li-Fi removes the limitations that have been put on the user by the Radio wave transmission such as Wi-Fi as explained above vide 4.1. Advantages of Li-Fi technology include:

a)Efficiency: Energy consumption can be minimised with the use of LED illumination which are already available in the home, offices and Mall etc. for lighting purpose. Hence the transmission of data requiring negligible additional power, which makes it very efficient in terms of costs as well as energy.

b) High speed: Combination of low interference, high bandwidths and high-intensity output, help Li-Fi provide high data rates i.e. 1 Gbps or even beyond.

c) Availability: Availability is not an issue as light sources are present everywhere. Wherever there is a light source, there can be Internet. Light bulbs are present everywhere – in homes, offices, shops, malls and even planes, which can be used as a medium for the data transmission.

 d) Cheaper: Li-Fi not only requires fewer components for its working, but also uses only a negligible additional power for the data transmission.

 e) 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 confined area and cannot be intercepted and misused, outside the area under operation.

 f) Li-Fi technology has a great scope in future. The extensive growth in the use of LEDs for illumination indeed provides the opportunity to integrate the technology into a plethora of environments and applications.

*Limitations of Li-Fi:

 Some of the major limitations of Li-Fi are:

·   Internet cannot be accessed without a light source. This could limit the locations and

· situations in which Li-Fi could be used.  It requires a near or perfect line-of-sight to transmit data.

·  Opaque obstacles on pathways can affect data transmission

·  Natural light, sunlight, and normal electric light can affect the data transmission speed

·  Light waves don’t penetrate through walls and so Li-Fi has a much shorter range than Wi-Fi

·  High initial installation cost, if used to set up a full-fledged data network

.·  Yet to be developed for mass scale adoption.

*Applications of Li-Fi:

Some of the future applications of Li-Fi could be as follows:

 a) Education systems: Li-Fi is the latest technology that can provide fastest speed for Internet access. So, it can augment/replace Wi-Fi at educational institutions and at companies so that the people there can make use of Li-Fi with the high speed.

b) Medical Applications: Operation theatres (OTs) do not allow Wi-Fi due to radiation concerns. Usage of Wi-Fi at hospitals interferes/blocks the signals for monitoring equipments. So, it may have hazardous effect to the patient's health, due to improper working of medical apparatus. To overcome this and to make OT tech savvy Li-Fi can be used to access internet and also to control medical equipments. This will be beneficial for conducting robotic surgeries and other automated procedures.

c) Cheaper Internet in Aircrafts: The passengers travelling in aircrafts get access to low speed Internet that too at a very high price. Also Wi-Fi is not used because it may interfere with the navigational systems of the pilots. In aircrafts Li-Fi can be used for data transmission. Li-Fi can easily provide high speed Internet via every light source such as overhead reading bulb, etc. present inside the airplane.

 d) Underwater applications: Underwater ROVs (Remotely Operated Vehicles) operate from large cables that supply their power and allow them to receive signals from their pilots above. But the tether used in ROVs is not long enough to allow them to explore larger areas. If their wires were replaced with light — say from a submerged, highpowered lamp — then they would be much freer to explore. They could also use their headlamps to communicate with each other, processing data autonomously and sending their findings periodically back to the surface. Li-Fi can even work underwater where Wi-Fi fails completely, thereby throwing open endless opportunities for military underwater operations.

 e) Disaster management: Li-Fi can be used as a powerful means of communication in times of disaster such as earthquake or hurricanes. The average people may not know the protocols during such disasters. Subway stations and tunnels, common dead zones for most emergency communications, pose no obstruction for Li-Fi.

f) Applications in sensitive areas: Power plants need fast, inter-connected data systems so that demand, grid integrity and core temperature (in case of nuclear power plants) can be monitored. The Radio communication interference is considered to be bad for such sensitive areas surrounding these power plants. Li-Fi can offer safe, abundant connectivity for all areas of these sensitive locations. Also, the pressure on a power plant 12 ‘s own reserves (power consumption for Radio communications deployments) will be lessened.

g)Traffic management: In traffic signals Li-Fi can be used to communicate with passing vehicles (through the LED lights of the cars etc) which can help in managing the traffic in a better manner resulting into smooth flow of traffic and reduction in accident numbers. Also, LED car lights can alert drivers when other vehicles are too close.

 h) Mobile Connectivity: Mobiles, laptops, tablets, and other smart phones can easily connect with each other. The short-range network of Li-Fi can yield exceptionally high data rates and higher security.

 i) Replacement for other technologies: Li-Fi doesn‘t work using radio waves. So, it can be easily used in the places where Bluetooth, infrared, Wi-Fi, etc. are banned.

*Conclusion :

Although there’s still a long way to go to make this technology a commercial success, it promises a great potential in the field of wireless internet. A significant number of researchers 15 and companies are currently working on this concept, which promises to solve the problem of lack of radio spectrum, space and low internet connection speed. By deployment of this technology, we can migrate to greener, cleaner, safer communication networks.

 The very concept of Li-Fi promises to solve issues such as, shortage of radio-frequency bandwidth and eliminates the disadvantages of Radio communication technologies. Li-Fi is the upcoming and growing technology acting as catalyst for various other developing and new inventions/technologies. Therefore, there is certainty of development of future applications of the Li-Fi which can be extended to different platforms and various walks of human life.