Science and Technology Daily reporter Yichen Wei
Apple iPhone13 will be officially released. On August 30, well-known Apple analyst Ming-Chi Kuo will support the latest research report on iPhone 13 _ strong2. Low-orbit satellite communications (LEO). Then this news quickly attracted the attention of netizens, and in a short period of time ascended the top search list.
Source: Vision China
What exactly is low-orbit satellite communication? Can our ordinary mobile phones be used? Is it really reliable?
low-orbit satellite What is the communication?
The low-orbit satellite system is part of the satellite Internet construction and is regarded as the latest and most promising satellite mobile communication system. The low-orbit satellite mobile communication system is composed of a satellite constellation, a gateway earth station, a system control center, a network control center, and a user unit. lays out multiple satellites on several orbital planes, and connects the satellites on multiple orbital planes by communication links. The entire constellation is like a large-scale platform connected in structure, forming a cellular service cell on the surface of the earth. Users in the service area are covered by at least one satellite, and users can access the system at any time.
low orbit satellites are compared to traditional geostationary orbit satellites.Compared with high-orbit satellites, the low-orbit mobile satellite communication system has the advantages of small satellites, low cost, high efficiency, easy launch (multiple satellites in one arrow), less propagation loss and delay time, and more reliable transmission quality. Cellular communication, multiple access, spot beam, frequency multiplexing and other technologies also provide technical support for low-orbit satellite mobile communications.
my country has already launched a satellite Internet layout
my country has a vast territory and complex natural terrain. When facing villages in remote mountainous areas, the cost of solving "from the sky" is lower than that of ground fiber optic cables. In April 2020, the National Development and Reform Commission made it clear that satellite Internet belongs to the category of new infrastructure. The 14th Five-Year Plan and the 2035 long-term goal also propose to strengthen the development of aerospace technology, and point out the construction of a high-speed ubiquitous, integrated, interconnected, secure and efficient information infrastructure, and enhance data perception, transmission, storage and computing capabilities.
As early as December 2016, the "Thirteenth Five-Year National Informatization Plan" also clearly mentioned that "through mobile cellular, optical fiber, low-orbit satellites and other methods, improve the network in remote areas and poor areas Coverage.” In this context, China Aerospace Science and Technology and China Aerospace Science and Industry have launched their own low-orbit communication projects "Hongyan" and "Hongyun" constellation programs, each will launch 300 satellites Established a space communication network with 156 low-orbit communication satellites. The two systems are planned to be completed in 2023. The two major aerospace groups have become the "national team" in the field of my country's low-orbit communication satellites. In terms of private investment, at the end of 2018, about 80 space technology start-ups in China represented by invested in this field, and space has become the "new frontier" of the Chinese business community.
Is low-orbit satellite communication safe?
Although satellite Internet, as a new form of infrastructure, has enriched a large number of new industrial chains and application scenarios for the country, under the hot air, more "cold" thinking is needed. Chang Liang, director of the Software Evaluation Center of the Institute of Microsatellite Innovation, Chinese Academy of Sciences, told the reporter of Science and Technology Daily that the development of satellite Internet is facing huge technical challenges, especially in the field of information security. The larger the number of facilities, the deeper the degree of integration, and the hidden dangers of the system. The bigger it is, the more likely it is that the satellite Internet will be controlled and paralyzed. How to ensure the information security of important national satellite communication networks while new technologies are continuously applied to various scenarios under the integrated air-space-ground communication system will also be a long-term core technical subject.
"Technical security risks faced by satellite Internet include monitoring, forgery and deception risks, network intrusion control risks, and communication interference risks." Chang Liang said that due to the lack of satellite network security standards, the current security protection of satellite systems is practical. The above is very weak and chaotic. At the same time, the characteristics and shortcomings of the micro-satellite Internet also increase the security risks of the satellite system.
Can current smartphones support satellite communication?
"If some domestic self-media said, " starlink will subvert 5G and serve the broadband Internet needs of global netizens", the low-orbit satellite system must achieve a total communication capacity roughly equivalent to that of 5G. It requires millions of low-orbiting satellites to be densely distributed in low-Earth orbit over densely populated areas and nearby cities in the global urban belt, while low-orbiting satellites are moving relative to the ground and have invalid coverage problems. This is completely in constellation design and system investment. Unimaginable.” Chen Shanzhi, professor-level senior engineer of China Information and Communication Technology Group Co., Ltd. believes that the broadband Internet access requirements of hundreds of users per square kilometer in the city give the spot beam coverage and interference control of satellite communications. Bring huge problems.
Chen Shanzhi introduced that the low-orbit satellite portable terminal uses a phased array antenna, and its surface antenna is about the same size as an iPad. Compared with 4G and 5G mobile phones, portable satellite terminals are bulky and consume more power. Satellite signals cannot cover indoors. Urban buildings block the direct line of sight (LOS) and are very sensitive to weather such as rain, snow, fog, and clouds. Coupled with tariff factors, it is not attractive to ordinary consumers in the city.
It is reported that the development of domestic low-orbit satellite communications is still at an early stage, and commercial conditions may not be available in the short term.
It is worth mentioning that communication without a SIM card is not allowed in the domestic market, because it does not comply with relevant national regulations such as real-name supervision. Previously, the loss mode of millet MIX4 also provided cardless networking services, and was eventually cancelled.
However, my country’s 5G technology and industry are leading the world, and 5G has begun commercial use. In addition, as the commercial aerospace, satellite manufacturing, and rocket launch industry chains become more and more perfect, my country has the means to accelerate the development of low-orbit satellite communications. Technology and industrial foundation. Pan Jun, Secretary-General of the Science and Technology Committee of the Eighth Academy of Aerospace Science and Technology Group, conservatively estimated that in the next 5-10 years, my country’s commercial small satellite launch demand alone will exceed 4,000, and the demand for commercial satellite manufacturing and launching will show explosive growth, which will bring space launch business. The geometric level skyrocketed.
Editor: Liu Yiyang
Review: Yue Liang
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