Review on Li-Fi: An Advancement of Wireless Network
Light Fidelity (Li-Fi) has attracted increasing attention with the rapid development of communication technology, In recent years 5G communication technology and Wireless Fidelity (WiFi) make people’s life more and more convenient
Introduction
The concept of visible light wireless communication (Li-Fi) technology was proposed by Professor Hass in the United Kingdom at the TED (Global Technology and Entertainment Design) conference in 2011, and the preliminary application of optical transmission data was successfully realized in 2012. In October 2013, the Fudan University experiment also successfully realized the wireless transmission of visible light indoors.
Through this technology, one LED light can be used for the normal Internet access of 4 computers, with a maximum rate of 3.25 Gbps and an average Internet rate of 150 Mbps
In November 2015, an Estonian startup company developed an ultra-fast network transmission technology for visible light communication. The Li-Fi technology users can send data at a maximum speed of 1 Gbps.
In 2016, China’s visible light real-time communication rate has been increased to 50 Gbps, and the communication rate is the world’s leading.
In 2017, due to the rise of Li-Fi technology, it was proposed to apply Li-Fi to the automatic avoidance system of new energy vehicles to improve the safety of vehicles during driving.
In the same year, Pure Li-Fi released a new type of integrated Li-Fi lamp, which supports 8 to 16 users to network at a time and transmits data at a speed of 45 Megabits.
In response to the various problems of underwater robots, as well as the shortcomings of underwater acoustic communication, optical fiber communication, and electromagnetic communication,
In June 2018, China developed Li-Fi communication to improve the flexibility and coordination of underwater robot cooperation And accuracy.
In November 2019, realized the reception principle of the intelligent advertising system through visible light communication. For the research and development of Li-Fi technology, there is great attention at home and abroad.
Even if Li-Fi cannot completely replace WiFi at this stage, its practical value and economic benefits still have great potential.
How does Li-Fi work?
Li-Fi (Light Fidelity) is a wireless data transmission technology that uses visible light as the transmission carrier. Its principle is to install a microchip on a light-emitting diode (LED) bulb and use the chip to control the light and dark changes of the light, and then according to the light bulb, The “1” and “0” representing the binary data respectively increase the frequency of light conversion to the point where the human eye cannot distinguish the light and dark changes.
At this time, the binary data is quickly encoded and transmitted by the light signal. By implanting a micro access device with an LED bulb as an Internet access point, computers and other terminals at home can access the LED bulb through the visible light emitted by the LED bulb, thereby connecting to the Internet, The light detector receives the light signal encoded by the microchip, and then converts it into an electrical signal through the amplifying processor.
This means that as long as the computer or mobile phone is placed under the light when there is light, we can download videos, apps, use the Internet, etc.
LED is a potential light source for realizing lighting and high-speed visible light communication in free space.
Comparative analysis of Li-Fi and WiFi
The essential difference between Li-Fi and WiFi is that Li-Fi uses light pulses to achieve data transmission, while WiFi uses wireless electromagnetic waves to transmit data.
Advantages of LiFi over WiFi
1.Not affected by electromagnetic waves. The WiFi technology we currently use electromagnetic waves for data transmission. During the transmission, it will be interfered with by other wireless electromagnetic waves, so that the network is stuck, the signal is unstable, and the video cannot be downloaded. On the other hand, Li-Fi technology is through the continuous flashing of LED lights to complete the transmission of wireless data, which does not have the problem of electromagnetic interference.
2. High security. The data transmitted by Li-Fi travels in a straight line of light and will reflect when encountering obstacles, so it will not penetrate. This improves the security of the Internet and eliminates our concerns about hacking the Internet, viruses, and Information leakage concerns.
3. High efficiency, energy-saving, green and environmental protection. WiFi wireless communication consumes a lot of power and has a low energy conversion rate. When a mobile phone is connected to a hotspot, its working current reaches more than 100 mA.
At the same time, a large amount of energy is consumed in the form of heat when the mobile phone is hot. The visible light communication technology uses light-emitting diodes as the light source, which is a cold light source, does not generate heat and consumes energy, and consumes less than 5% of the luminous power, which is almost zero-consumption communication.
The cost of ordinary diodes is very low, which is in line with the modern green environmental protection concept. In 2018, Wu Jiangxing, an academician of the Chinese Academy of Engineering, released the first visible light communication chip at the first Smart Expo. This chipset can support high-speed transmission in the order of Gega bits per second, which shows that the transmission rate of Li-Fi is much faster than WiFi.
4.It can be flexibly applied in various places. Currently, WiFi is widely used in large-scale places, such as hospitals, shopping malls, and schools. However, the shortcomings of WiFi susceptibility to interference are becoming more and more obvious, such as unstable network signals, interrupted data transmission, and low data security. Compared with WiFi, Li-Fi can make up for the shortcomings of WiFi.
Disadvantages of Li-Fi compared to WiFi
1.The application area is limited. As the light is blocked, data signal transmission will be interrupted, which makes Li-Fi can only be used in specific areas. When Li-Fi is used in an outdoor place, it is necessary to ensure the distribution of light sources within a limited range.
2.Point-to-point uni-directional transmission. In the early days, Li-Fi was not capable of two-way transmission like WiFi, only point-to-point transmission. At present, the research on Li-Fi two-way transmission is constantly improving, and there is certain progress, and one-to-multipoint and multipoint-to-point optical communication have been realized.
3.Light is easily interfered with by other lights and blocked by obstacles. When the outdoor sunlight is strong, Li-Fi will be interfered with by the ambient light, resulting in continuous signal transmission. When we block the light with our hands or other objects, it will also block the signal transmission and the signal will also be interrupted.
4.Complex photo-electric device system. Li-Fi technology needs to be applied to devices such as transmitters, receivers, photodetectors, and data processors. How to make the technical parameters of these devices match each other is also a problem that needs to be solved for Li-Fi technology.
5G network communication
The full name of 5G is “the fifth-generation mobile communication network.” As people have higher requirements for network technology, the transition from the 2G era to 3G, from the 3G era to the general application in the 4G era, and then to the arrival of the current 5G era.
The theoretical transmission speed of 5G can reach tens of GB per second, which is hundreds of times higher than the transmission speed of 4G networks
According to people’s needs, network communication is not only a one-sided consideration of speed, but the transition from 4G to 5G has greatly improved the speed, and it also has the characteristics of low latency and stability.
5G technology has promoted the process of intelligence, making driverless driving a reality. In the future, maybe we will no longer have to worry about driving license tests. We will directly set up the program in the car and choose the destination we want to go to the place.
The smart home is also an area where 5G technology has developed greatly, a single button can control all electrical appliances in our home. Li-Fi is based on optical communication technology. In the future technical field, Li-Fi will occupy a certain position and is considered to be the most promising solution for 5G networks and above.
The Usage of Li-Fi Technology
In recent years, Li-Fi technology is gradually being used in various fields, such as the Internet, aviation, underground operations, safety projects, agricultural projects, indoor positioning, etc. Although it also has its own limitations, if we can make good use of its advantages, our communication technology will develop better.
1.The LED required for Li-Fi is installed in the flashlight of the mobile phone, instead of lighting, it can also be connected to the Internet. When there is no WiFi hotspot, you can turn on the flash to scan the code and pay. Li-Fi-based payment technology has been tried in China.
2.In terms of down-hole operations. We all know that coal mining is a dangerous job. When WiFi technology is applied to work underground, the penetration of WiFi signals becomes weak and the data signal transmission is not continuous, which easily affects the precise positioning of miners, which is not good for safety produce.
The use of Li-Fi technology in closed spaces underground also has the advantage of high-speed data transmission. We can install LED lights with microchips at intervals in the mine tunnel, and install such LED lights on the helmets of workers.
After the lights on the channel detect the location identity, and the current time of the staff, the information is transmitted to the terminal, and then processed and displayed on the computer screen. In this way, the signs of life and location of workers in the mine can be detected at any time, reducing casualties.
3.Smart car lights. Install LED lights with microchips on the car lights. The car lights are used as receivers to receive information, decode the light signals transmitted by the chip, and display the information in front of the car owner through the display screen. When two vehicles are very close or a pedestrian passes by, the lights will send a signal to decelerate to remind the owner to activate the automatic avoidance system, thereby effectively avoiding traffic accidents.
4.In aviation. When an airplane is flying in the air, the mobile network cannot be used because the reception and transmission of mobile phone signals will interfere with the flight of the airplane. Therefore, passengers are required to turn off their mobile phones or turn on the flight mode during takeoff and landing and flight. If Li-Fi technology is applied, this problem may be solved.
By installing specific LED lights in the cabin, data can be transmitted normally, and passengers can use the Internet at any time without affecting the flight.
The outlook of LiFi Technology
As a high-tech that faces the cross-integration of LED lighting, communications, things that use the internet, smart cars, aviation, and other fields, Li-Fi has broad market application prospects in the future. Li-Fi will become a new direction for LED applications. As a new type of technology, the development of Li-Fi technology still faces many challenges due to the limitations of LED broadband and the sensitivity of photodetectors.
At present, the development, research, and innovative application of key technologies in the visible light communication field, which will accelerate the breakthrough of the bottleneck of key core technologies in visible light communication, and actively promote the development and industrialization of visible light communication technology.
Currently, Li-Fi and WiFi have their own advantages and disadvantages. If they are combined and applied, it will make our lives more convenient.
