747269429747269429747269429747269429-lifi.docx
- 1. Introduction Visible light communication (VLC) is the term given to an optical wireless communication system that conveys information by modulating light that is visible to the human eye. LiFi (light fidelity) is a bidirectional wireless system that transmits data via LED or infrared light. It was first unveiled in 2011 and, unlike wifi, which uses radio frequency, LiFi technology only needs a light source with a chip to transmit an internet signal through light waves. Limitations of pre-existing wifi model a) Capacity: The radio waves used by Wi-Fi to transmit data are limited as well as expensive. With the development of 3G and 4G technologies, the amount of available spectrum is running out. b) Efficiency: There are 1.4 million cellular radio masts worldwide. These masts consume massive amounts of energy, most of which is used for cooling the station rather than transmission of radio waves. In fact, the efficiency of such stations is only 5%. c) Availability: Radio waves cannot be used in all environments, particularly in airplanes, chemical and power plants and in hospitals. d) Security: Radio waves can penetrate through walls. This leads to many security concerns as they can be easily intercepted. Li-Fi addresses the aforementioned issues with Wi-Fi as follows: a) Capacity: The visible light spectrum is 10,000 times wider than the spectrum of radio waves. Additionally, the light sources are already installed. Hence Li-Fi has greater bandwidth and equipment which is already available. b) Efficiency: LED lights consume less energy and are highly efficient. c) Availability: Light sources are present in all corners of the world. Hence, availability is not an issue. The billions of light bulbs worldwide need only be replaced by LEDs. d) Security: Light of course does not penetrate through walls and thus data transmission using light waves is more secure. APPLICATIONS OF LI-FI Li-Fi technology can find application in a wide variety of fields. A detailed discussion of its various applications is given below. (i) Medical and Healthcare Due to concerns over radiation, operating rooms do not allow Wi-Fi and even though Wi-Fi is in place in several hospitals, interferences from computers and cell phones can block signals from medical and monitoring equipment. Li-Fi solves these problems. Lights are an essential
- 2. part of operating rooms and Li-Fi can thus be used for modern medical instruments. Moreover, no electromagnetic interference is emitted by Li-Fi and thus it does not interfere with any medical instruments such as MRI scanners. (ii) Airlines and Aviation Wi-Fi is often prohibited in aircrafts. However, since aircrafts already contain multiple lights, thus Li-Fi can be used for data transmission. (iii) Power Plants and Hazardous Environments Wi-Fi is not suitable for sensitive areas like power plants. However, power plants still require fast and interconnected data systems for monitoring grid intensity, demand, temperature etc. In place of Wi-Fi, Li-Fi can provide safe connectivity throughout the power plant. Li-Fi offers a safe alternative to electromagnetic interference due to radio waves in environments such as petrochemical plants and mines. (iv) Underwater Explorations and Communications Remotely operated underwater vehicles or ROVs work well except in situations when the tether is not long enough to fully explore an underwater area or when they get stuck. If instead of the wires, light were used then the ROVs would be freer to explore. With Li-Fi, the headlamps could also then be used to communicate with each other, data processing and reporting findings back to the surface at regular intervals, while also receiving the next batch of instructions. Radio waves cannot be used in water due to strong signal absorption. Acoustic waves have low bandwidth and disrupt marine life. Li-Fi offers a solution for conducting short-range underwater communications. (v) Traffic Li-Fi can be used for communications between the LED lights of cars to reduce and prevent traffic accidents. LED headlights and tail-lights are being implemented for different cars. Traffic signals, signs and street lamps are all also transitioning to LED. With these LED lights in place, Li-Fi can be used for effective vehicle-to-vehicle as well as vehicle-to-signal communications. This would of course lead to increased traffic management and safety. (vi) GigaSpeed Technology The Li-Fi Consortium provides the fastest wireless data transfer technology presently available. Our current solutions offer effective transmission rates of up to 10 Gbps, allowing a 2 hour HDTV film to be transferred in less than 30 seconds. This can be extended to several 100 Gbps in future versions (vii) Smart Lighting Street lamps can in the future be used to provide Li-Fi hotspots and can also be used to control and monitor lighting and data. Conclusion
- 3. Li-Fi is still in its incipient stages and thus offers tremendous scope for future research and innovation. Li-Fi is advancement in wireless communication systems which possess high security, speed than existing wireless data transmission systems. Each and every LED can act as a transmitting device if it is perfectly implemented in real time. The main advantage of Li-Fi is its unregulated bandwidth unlike radio frequencies which contains a limited bandwidth. Now-a-days increment of radio frequencies usage led to limit some application which can be achieved by Li- Fi. All the equipment by default uses 2.4 Ghz frequency, which makes the equipment very difficult to function as they are interfered. If the medical equipment is interfered with the radio frequency it may fall under faulty condition and can menace patients’ lives. The problems of CCTV surveillance in the hospitals are vanquished by the proposed system which is reviewed in this paper. The output of receiver section is the analog form which can be displayed in television module or monitor