Recently, high-end mobile phones that can "go to the stars" have been attracting people's attention, the connection between satellites and mobile phones may not be difficult, but it is not easy to commercialize, the dream of using low-orbit communication satellites to achieve global mobile communication without dead ends is very full, but the reality is skinny.
◎ Liu Yan, reporter of this newspaper
Recently, a report has once again boosted the attention of mobile phones directly connected to satellites. According to the reference information, Ericsson is developing a new means of communication: anywhere on the earth, without the need for large ground equipment or ground base station transit, only a smartphone can exchange data with artificial satellites. It is expected that this new communication method will be commercially available in 2025, and by 2050 it is expected to achieve communication speeds comparable to current 5G specifications.
As early as the 20s of the 90th century, relevant institutions were envisioning "ubiquitous" communication networks, and a number of R&D institutions and commercial companies followed this goal. From 2017 to 2022, 3GPP and other institutions vigorously carried out and promoted the exploration of 5G-based satellite communications. On April 4, AST SpaceMobile, a US satellite communications startup, announced that it had opened the world's first space-based cellular voice call. As 25GPP classifies satellite networks as non-terrestrial networks (NTNs) and carries out research and standardization work, the prelude to satellite-ground integration slowly begins.
Technology and business models need to be balanced
Recently, high-end mobile phones that can "go to the stars" have been attracting people's attention, the connection between satellites and mobile phones may not be difficult, but it is not easy to commercialize, the dream of using low-orbit communication satellites to achieve global mobile communication without dead ends is very full, but the reality is skinny.
From 1997 to 1998, the United States Iridium Satellite Communications Company (hereinafter referred to as Iridium Corporation) commissioned Motorola to design a global mobile satellite communication system, because 72 (6 of which are spare stars) artificial satellites are arranged like the distribution of electrons outside the nucleus of iridium atoms, so the system is called Iridium.
As the originator of commercial low-orbit satellites, Iridium basically does not rely on ground facilities to achieve global coverage. However, the world's most creative system ended in March 2000 with the declaration of bankruptcy by Iridium.
Recalling this past, Chen Shanzhi, deputy general manager of China Information and Communication Technology Group Co., Ltd., sighed: "In the 20s of the 90th century, the Iridium system (low-orbit satellite communication) and terrestrial cellular mobile communication (GSM) that appeared almost at the same time competed with each other, but Iridium filed for bankruptcy because of huge R&D and system construction costs, and terrestrial cellular mobile communication developed from 2G to 5G because of its large user base and obvious cost advantages, and the commercialization road was very successful." ”
Objectively speaking, at that time, Iridium had broken through key technical problems such as inter-satellite links, the basic structure and procedures of the system were initially completed, and began to provide major services including mobile phones, paging and data transmission. From this point of view, Iridium succeeded. However, Iridium, which planned to invest a total of 23.1998 billion US dollars, actually cost more than 50 billion US dollars by the completion of the networking in 40, and the huge cost made Iridium more than 100 billion US dollars in debt when it went bankrupt, but there were only more than <>,<> customers at that time (it is estimated that about <> million users can achieve profitability).
Not only did the actual cost far exceed the investment budget, but the expensive Iridium also suffered a cold shoulder in the market due to product quality and service failure to meet customer needs. It is particularly noteworthy that when Motorola started the construction of the Iridium, most of the cities, suburban villages, traffic arteries, tourist attractions and other densely populated areas were covered by the ground network, and Motorola's idea that "people are willing to pay a little high price for a global number access" was too wishful thinking, resulting in the original Iridium eventually becoming a milestone in modern communications.
"Advanced technology, price will not become an obstacle", although this view has always had a market selling point, but the lesson left by Iridium is that the concept is ahead, the technology is advanced and difficult to compete with the market demand, and the technology and business model always need a balance point, which can be seen from the rebirth of Nirvana after the restructuring of Iridium to industry applications.
Build 5G non-terrestrial networks
The ideal will never die, and Ericsson plans to take 5G out of the earth.
In July 2022, Ericsson announced that it will conduct detailed research including multiple studies and simulation simulations with Thales of France and Qualcomm of the United States, and the three parties plan to test and verify 7G non-terrestrial networks with a focus on smartphones.
This means that future 5G smartphones can use 5G connectivity anywhere on the planet, while broadband data services provide full global coverage, including areas that are typically only covered by traditional satellite phone systems with limited data connectivity.
As Ericsson Senior Vice President and Chief Technology Officer Eric said, this test and validation by Ericsson, Thales and Qualcomm will be an important milestone in the history of communications, and its final result may show that users can access high-end, secure and economical communication services from anywhere on the planet through joint 5G satellites and ground connections, whether in the middle of the ocean or in the most remote forests.
The goal of this test is to verify that the various technical components required to implement 5G non-terrestrial networks, including 5G smartphones, satellite payloads and terrestrial 5G network components, as well as whether the form factor of the smartphone can support 5G non-terrestrial networks, so that future 5G smartphones can be successfully transformed into satellite phones.
Ericsson will validate a 5G Virtual RAN (vRAN) stack that has been specifically modified to handle radio signals propagating through low-Earth orbit satellites (simulating the propagation of 5G radio waves in the vacuum of space and the Earth's atmosphere), Thales will validate 5G wireless satellite payloads suitable for deployment on low-Earth orbit satellites, and Qualcomm will provide test phones to verify that future 5G smartphones can be connected to 5G non-terrestrial networks.
Eric added that it is too early to discuss when the 5G prototype satellites resulting from the collaboration will be launched into orbit and put into service, but this high-tech ground testing and validation effort planned by Ericsson, Thales and Qualcomm is key to making this a reality.
Satellites used for communications will operate in low-Earth orbit, which is closer to Earth than geostationary satellites about 3,6 kilometers above the surface, and if the performance of communication semiconductors mounted on smartphones is improved, satellites can be connected even without the use of large antennas fixed on the ground.
Obviously, establishing 5G connectivity with low-orbit satellites will greatly enhance the roaming service capabilities of 5G smartphones.
Satellite-ground integration is the mainstream direction in the future
Terrestrial cellular mobile communication has been developed all the way to 5G, and the scale of users has been expanding, and the degree of commercialization is relatively high. In contrast, the commercialization of satellite communications is clearly not on the same order of magnitude as terrestrial cellular mobile communication systems.
At present, the more mature Starlink plan focuses on providing users with direct communication services through its low-orbit satellites, although it is a supplement to terrestrial mobile communications, but does not consider the deep integration between the two.
The non-terrestrial network in the 5G R17 version standard family that has been supported by mainstream smartphone chips and terminal manufacturers aims to incorporate non-terrestrial networks such as satellite communications into the mobile communication system, realize the integration and joint commercial use of terrestrial mobile communications, and is by no means the "two skins" development of terrestrial mobile communication networks and satellite communication networks.
Sun Zhili, a professor at the University of Surrey in the United Kingdom, said that cellular mobile communication has always been for ground users, until the demand for global coverage poses a huge challenge to terrestrial cellular mobile communication, the advantages of satellite communication are displayed, thus becoming an indispensable part of 5G and future 6G technology.
Sun Zhili further pointed out: "In order to support the needs of 5G/6G in terms of large connectivity, low latency, and high reliability, it is inevitable that satellite communication will move from high orbit to full orbit (high, medium and low orbit) and from narrowband to broadband. From the perspective of standardization and industrialization, the evolution paths of the two industrial ecosystems of ground communication and satellite communication will be perfectly integrated. ”
Huawei believes that only by focusing on cells and supplemented by satellite communications can it build a network with global coverage suitable for various application scenarios. However, even to build such a communication network, there are still certain challenges, Huawei 6G Chief Scientist Wang Jun pointed out at the 2023 Global 6G Technology Conference that satellite direct connection to mobile phones is feasible, but improving spectrum efficiency and O&M management is difficult.
"High-orbit satellites are far from the Earth and cover a large area, but the time is extended; Low-orbit satellites are close to the Earth, with small latency, but small coverage area. Therefore, many satellites are used to form constellations to achieve global coverage. Space orbit and spectrum are scarce resources, and the combination of multiple satellites can increase spectrum utilization and effectively use precious spectrum resources. Sun Zhili further pointed out that the spectrum resources that can be used for satellite communication are relatively limited, and the beams generated by satellites are much larger than terrestrial wireless networks, making the utilization rate of spectrum far inferior to terrestrial wireless networks, which will directly affect the capacity of communication.
Sun Zhili stressed that when introducing a low-orbit satellite network, it is necessary to make a trade-off between the number of satellites and the coverage of satellites. Dynamic management of satellite networks can reduce the transmission cost of satellite networks and help meet the requirements of network quality of service.
Wang Jun pointed out in particular: "At present, each satellite of low-orbit satellites basically has only a few minutes of service time, and a large-scale user switch occurs every few minutes. In large-scale user management and operation, how to achieve seamless switching between stars and stars will be a big challenge for a long time to come. (Source: Science and Technology Daily)