LED best application? LI-FI pros and cons geometry?
After the world was created, God first thought of having light, and all kinds of magical and colorful light, for us to expel the fear of darkness, added a monotonous world. After the modern society was created, the first thing people think of is the interaction of information, so from the complicated wired transmission to the simple wireless transmission, from several bit turtle speed to several Gbit high speed, the iterative development of information technology makes us disperse the world. All over the place, but the distance between each other is unprecedented.
Our endless demand for higher speeds, easier access, and cheaper prices for information networks is forcing generations of communications technology innovation. From the initial beacon tower to the current fiber optics, the high-speed and efficient 'light' has been the most commonly used communication method since ancient times. Since the beginning of the digital age, how to get rid of the constraints of cables has always been the research direction. As early as 2004, Professor Keio University in Japan proposed the theory of visible light communication. At that time, wireless optical communication research focused on infrared technology. However, with the improvement of LED technology, LEDs were used as wireless optical communication devices. It came into being, and Professor Haas of the United Kingdom also gave it the name of LI-FI.
LI-FI application
On the one hand, LED wireless optical communication is suitable for the current stereo of the lighting industry. On the other hand, high-frequency flickering is one of the inherent characteristics of LED. By using this effectively, the light can be binary coded quickly, and the illumination itself is An essential presence for all occasions. For a time, the Internet of Things, Internet of Vehicles, smart homes and other places have increased the value of LI-FI applications and business to an infinite number of places.
For example, in the accurate positioning of indoors, indoor GPS cannot function effectively, and it is difficult to accurately locate indoors in real time. The indoor ubiquitous light source is used as a launching carrier. When the user enters the lighting area of ​​the luminaire, the front camera of the smart phone is used to receive and identify the optical signal, and the unique identification information sent by the luminaire is parsed. The corresponding location information is determined in the map database by using the acquired identification information, and the positioning is completed.
At present, in the case of signal stability, the optimal positioning accuracy of indoor positioning applications based on WiFi and Bluetooth is 3-5m; indoor positioning technology based on optical communication can accurately identify two LED lights under conventional household layout, accuracy At around 1m. In mine operations, shopping malls, warehouses and other places, more precise light positioning gives them a qualitative change.
Highlights have many drawbacks as well.
However, the transmission of optical signals cannot penetrate obstacles, and if there is an obstacle, the transmission of information stops immediately. At the MWC 2014 conference last year, Pure LiFi's team showed us the real LiFi lighting. On-site Pure LiFi demonstrated the process of transmitting HD streaming video to a TV. If the light is covered, the picture will stop.
Pure LiFi system
Secondly, the communication distance is limited. According to the laboratory data, the LI-FI that achieves the communication rate of Gbps level, the communication distance between the receiver and the transmitter is only 10 cm, and the signal working range is relatively small, and the transmitting and receiving sides cannot The displacement is too large. Since the displacement cannot be too large, and there is no obstacle in the middle, the meaning of wireless is greatly reduced. Is it better to pull a fiber directly between the two?
In addition, since this is based on the visible light communication of the existing LED lighting products, the lighting and data communication are combined into one, which saves the cost to a certain extent, but the optical signal interference between the LED bulb and the bulb needs to be solved, and the user is the only one. The receiving end faces different transmitter bulbs. How to shield the same type of interference affects the development of LI-FI.
Still in its infancy
In my opinion, the application prospect of LI-FI is wide, but most of the fields can be replaced by other products, and even better results than LI-FI. At present, many shortcomings lead to the actual use of LI-FI features. Imagined a lot, let alone a hot discussion of WI-FI. Of course, at present, LI-FI is in the initial stage of the industry, and the unified front in the industry is particularly important, especially on key issues such as the formulation of industry standards. It is not like other communication technologies such as Bluetooth, but it has been delayed for several years for standard problems. In the early stage of R&D, it is the key to LI-FI to absorb the knowledge of other communication technologies, to develop relevant communication protocols, to specialize in its own characteristics, and to focus on the application of the Internet of Things. ZigBee and Bluetooth are the biggest competitors of LI-FI.
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