Li-Fi is a technology based on a diode that emits light ¨Leds¨ visible, is characterized by transmitting information by means of the light spectrum since it has the ability to turn on and off at speed not perceptible by the human eye with a configuration vinary zero when it turns off and one when it is turned on logically it must have a receiver that interprets these signals, added the speed of the light we will have a gain in the speed of data transfer being this the same for all the devices without saturation or see affected navigation speed, not having electromagnetic waves is more friendly to the environment but at the same time having limitations because its light spectrum can not penetrate the walls being the complement of the Wi-Fi network in certain environment, Li -Fi is a more secure connection since not being able to cross the objects the only ones that will have access to this wireless internet network would be only the devices that are under the Li-Fi signal.
The LED when it is on and when it is off can provide two states according to what is called 1 and 0 which indicates that the LED can be on or off, the use of rapid pulses of light to transfer data without physical connection, said The method is called Visible (VLC).
The LEDs can turn on and off very quickly something that is not possible to be visible by the human eye therefore the light source seems to be constantly on. When these signals are transmitting to the receiver through the wireless channel, the photodiodes will convert these optical signals into electrical signals and the original information will be recovered.
Li-Fi is a technology that aims towards the development of the most intelligent and intelligent society since every day advances in leaps and bounds. At present, the Internet is of great importance, because of its usefulness, the demand of this service by network users have caused it to become saturated, which results in the lack of data speed, this has led to look for other technology methods to have a more efficient and effective service, the recent research of mobile telephony professor Harald Haas of the University of Edinburgh (Scotland UK), carried out research on light-fidelity (LI-FI) , this new technology works with characteristics similar to WI-FI technology. The li-fi means Light-Fidelity. Li-Fi is the transmission of data through the light by sending data through an LED bulb has a radio frequency communication through the bandwidth and high data rate. That is why more frequently it is possible to provide a greater bandwidth to each user to transfer information with greater speed.
Li-fi is the latest version of Wi-Fi technology that uses visible light, offers greater speed than other broadband. li-fi has a wider network area, improved traffic handling capacity and is cheaper than wi-fi. The VLC system is compared to other wireless communication systems that are in current use such as LAN and Wifi. LAN is available in a very short range and is not mobile. And wi-fi has low data traffic handling capacity, as the number of users increases wi-fi becomes unable to achieve the user's need. Li-fi offers a significant capacity to solve this problem with wi-fi. It transmits data by activating and deactivating the LEDs by rapidly changing the intensity of the light that is not detected by the human eye. The data transmission speed is about 10 Gbps using the bright white LED. When a receiver image sensor is used, the light sources are almost perfectly separated into a matrix of pixels because there is a massive number of pixels and optical signals are emitted separately from each pixel this prevents the signals from mixing, allowing communication , although many LED transmitters and Superfluous Lights (sources of noise) as the light of the lamps are present.
General Overview of the li-fi Technology
An advanced way of transferring information could change the way that systems. Li-fi uses visible light to transfer data between two devices that have no physical connection. This idea is inspired by visible light communication (VLC) that uses visible LED light for data transmission. An infrared remote control works by switching an IR LED on and off with 38kHz frequency. This light is detected by the sensor and the microcontroller connected in TV converts it into commands. Instead of rf. Li-fi uses visible light to transfer data between two devices.
Wireless optical communication through visible light has advantages and disadvantages. The disadvantage includes line of sight to support high data rate transmission rate. If the line of sight is not appropriate between the end of the transmitter and the speed of transmission of the final data of the receiver will be degraded. Another system of visible light communication is essentially short-range applications. Any obstruction and interference can affect the performance of the system.
The visible light communication system (VLC) has several advantages to become rival wireless technologies. Due to small amounts of radio frequency spectrum, if traffic increases in the network. The light itself has a bandwidth 10,000 times greater than radio waves. Because the data transfer is more efficient. Radio waves are harmful for humans to penetrate the body and can cause mutation. So it's safe. Since No sign of penetration through the walls, so no one can hack. Therefore, it is safe to use this new technology.
To actually send data through LEDs, such as Audio Message, it is necessary to modulate them in the signal. The context of communication by visible light, this Carrier consists of pulses of light sent in short intervals.
The data must be transmitted through which the data is fed to the LED that drives the LED. The data is traversed through a channel and received by a photo detector that converts an optical signal into an uplink electrical signal with a frequency of 38kHz. The received data is transmitted via USB for TTL communication protocol.
The receiving unit is implemented using photodiodes. The photodiode detects visible light and changes the optical signals Electrical signals. The photodiodes can convert it into current and voltage depending on the operating mode. Photodiodes are similar to the general type of semiconductor diode that exposed to light. Other data is decoded to retrieve original information and pass it to system 2. The medium between the transmitter and the receiver is only the optical channel, not any physical connection is made between them. This System can transfer various types of data such as text and audio data into a signal.
LIFI is the next version of wifi that is fast and cheap. It is based on visible light communication (VLC). VLC is a communication medium that uses visible light between 400 THz (780nm) and 800THz (375nm). As an optical carrier for data transmission. It uses faster pulses of light to transmit information. The LEDs can be on and off to generate digital chains of different combinations of 0s and 1s.
The LEDs can be used as a source or emitter, by modulating the light with the data signal. The LED output appears same for the human eye, by virtue of the rapid flash rate of the bulb. Data transmission speed greater than 100 Mbps may be possible by using high-speed LEDs with the help of various multiplexing techniques. Communication data speed of visible light can be increased by sending data transmission in parallel using a multiple of LEDs where each LED sends a different data stream.
The Li-Fi emitter system consists of 4 primary parts
2. Circuit of the RF power amplifier (PA)
3. Printed circuit board (PCB)
This system offers several advantages such as generating more brightness, higher color quality and high luminous power of the emitter in the range of 150 lumens per watt or more. The structure is mainly robust without the typical degradation and failure mechanisms associated with tungsten electrodes and glass-to-metal seals, resulting in a useful life of 30,000 hours. In addition, the unique combination of high-temperature plasma and digitally controlled solid-state electronics results in a family of inexpensive production bulbs, scalable in packages of 3,000 to more than 100,000 lumens.
VisibleLlight Communication (VLT)
Previously, radio waves were expensive and less secure. Infrared, can only be used as for the sake of eye safety. Gamma rays can not be used as they can turn out to be dangerous. Ultraviolet light is good for the place that is free from humans can be very harmful to humans. Since visible light does not produce effects, it can be safe to use and also having a greater
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