Did you have a good time during the four-day “May Day” holiday? Xiangning also contributed to the national road traffic sector and boosted GDP growth. But to be honest,if you don’t go out to play, you really don’t know how comfortable it is to lie at home, connect to Wi-Fi, play on your phone, and listen to music with Hi-Fi…
(Source: Sina Blog)
Huh? Wi-Fi? What? Hi-Fi?? What’s going on? Li-Fi??? Calm down, welcome to Xiangning’s little classroom… (What an awkward introduction, but that’s how it is 
)
1
Wi-Fi, remember this~~ it’s not “WiFi” or “Wifi”, because neither of them has been certified by the Wi-Fi Alliance(full name: Wi-Fi Alliance, in English: Wi-Fi Alliance). You may not remember, but Wi-Fi stands for Wireless Fidelity, which translates to “Wireless Fidelity Transmission System“; in Chinese, Wi-Fi is also known as “mobile hotspot”.
You may deal with Wi-Fi every day, at home, in the office, in cafes, train stations, or even on buses, where wireless hotspots are available, and some can even be accessed for free; with the popularization of data traffic billing, some people can also become “walking hotspots”, providing everyone with internet access wherever they go. But do you know how Wi-Fi sends and receives signals?
Wi-Fi is a technology that uses radio waves for computer network data transmission. A Wi-Fi system mainly consists of an AP (Access Point) and a wireless network card. AP generally refers to a network bridge or wireless access node, which is a HUB or router with a built-in wireless transmitter that connects wired local networks with wireless local networks. A device equipped with a wireless signal receiver, i.e., a wireless network card, can receive wireless signals emitted by the AP.
What? Don’t understand? Simply put, a Wi-Fi system consists of: an AP that sends signals and a wireless network card that receives signals.
The rapid development of technology is vividly reflected in Wi-Fi technology. Similar to Bluetooth technology, Wi-Fi is also a short-range wireless transmission technology, with a transmission rate of 10-20 Mbps/s; however, its transmission distance far exceeds that of Bluetooth technology, reaching up to 100m (Bluetooth is 15m).
(Source: Pacific IT Encyclopedia)
2
The advancement of science and technology has given many things incredible capabilities. Look at this light bulb 💡, it’s round and bright~ why not…
—use it to transmit information?!
Soon, dedicated and enthusiastic scientists 
created the now popular term Li-Fi. Li-Fi is an abbreviation for Light Fidelity. Intuitively, Li-Fi represents: optical fidelity technology; commonly referred to as: visible light wireless communication, a new wireless transmission technology that uses the visible light spectrum (like the light emitted by a light bulb) for data transmission.
The Li-Fi technology was first proposed by Professor Harald Hass from the University of Edinburgh’s Department of Electronic Communication and his team.
(Source: Guokr)
Currently, Li-Fi technology has not been widely applied and is still in the laboratory stage.Li-Fi is a bidirectional, high-speed wireless communication technology that can also be compatible with RF communication, with transmission rates much higher than Wi-Fi. In China, real-time transmission rates of 731 Mbps/s have been achieved with watt-level high-power fluorescent LED single paths. Using Li-Fi for information transmission not only has high bandwidth and high-speed characteristics like traditional fiber optic communication methods but also has the advantage of being unaffected by geographical limitations and electromagnetic interference.
How does Li-Fi work? Simply put, by implanting a tiny chip in lighting devices like light bulbs, it can turn them into devices similar to AP (Wi-Fi hotspots), allowing terminals to install matching receiving devices to access the network.
(Source: OFweek Internet of Things)
However, Li-Fi has one characteristic—it cannot “penetrate walls”. We often encounter a situation where you have a Wi-Fi router at home that not only allows the family to share the network but also lets the neighbor often “piggyback” on your network (this is really not very ethical). There are pros and cons; visible light, this magical thing, can be blocked by a small piece of cardboard. Therefore, for gamers, Li-Fi is simply a guarantee of internet speed, a blessing for champions.
(Source: China Mobile)
3
As the times progress, people have higher demands for the sound and images of multimedia devices around them. At this time, Hi-Fi emerged. Yes, unlike the previous two, Hi-Fi is not a technology for information transmission.
Hi-Fi is an abbreviation for High Fidelity, which translates to “high fidelity”, defined as: sound reproduction that is highly similar to the original sound. In simple terms, Hi-Fi is a term for high-quality sound systems. Clearly, Hi-Fi is not a proprietary term in the traditional network information transmission field; Hi-Fi is an information transmission system composed of audio systems (signal transmission devices) and human ears (signal receiving devices).
In today’s society, whether it’s portable devices or complex home assembly devices, people, especially young people, increasingly prefer to use Hi-Fi to experience immersive stereo sound.
(Source: Tianji Net)
Finally, Xiangning wants to tell everyone: whether it’s Wi-Fi, Li-Fi, or Hi-Fi, their “Fi” all stands for “Fidelity”, which means “fidelity”. After all, whether it’s sound or information, distortion is unacceptable.
(Source: Tencent)
References:
[1] Zhang Chunfei. Principles of Wi-Fi Technology and Future Development Trends [J]. Digital Community & Smart Home, 2008(11):30-32.
[2] Li Yang. Research on Wi-Fi Technology Principles and Applications [J]. Science and Technology Information, 2010(06):241.
[3] Zi Yingjie, Li Xue, Wu Zhihan. LiFi Makes the World More Perfect [J]. China High-tech Zone, 2017(21):201.
[4] Chi Nan, Shi Meng, Hai Nair, Niu Wenqing. LiFi: Current Status and Outlook of Visible Light Communication Technology [J]. Journal of Illumination Engineering, 2019, 30(01):1-9+14.
[5] Zoumot Zaid, Davey Claire, Jordan Simon, McNulty William H, Carr Denis H, Hind Matthew D, Polkey Michael I, Shah Pallav L, Hopkinson Nicholas S. Endobronchial valves for patients with heterogeneous emphysema and without interlobar collateral ventilation: open label treatment following the BeLieVeR-HIFi study. [J]. Thorax, 2017, 72(3).
[6] Z. Salman, P.J. Baker, S.J. Blundell, S.P. Cottrell, S.R. Giblin, A.D. Hillier, B.H. Holsman, P.J.C. King, T. Lancaster, J.S. Lord, I. McKenzie, J. Nightingale, F.L. Pratt, R. Scheuermann. HiFi—A new high field muon spectrometer at ISIS [J]. Physica B: Physics of Condensed Matter, 2008, 404(5).
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