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[Text/Observer Network columnist Bai Yujing]

If time goes back to January 3, 2024, I am afraid that many people will not realize that on the other side of the distant ocean, a butterfly flapped its wings silently - on this day, SpaceX launched the first batch of 6 Starlink satellites that connect directly to mobile phones. A revolutionary storm of mobile phones directly connecting to satellites is quietly getting closer and closer to everyone.

On July 3rd, local time, SpaceX launched 20 Starlink satellites, 13 of which are Starlink satellites that connect directly to mobile phones. In just 6 months, the total number of Starlink satellites that connect directly to mobile phones has exceeded 100, reaching 103. "Rapid as lightning" is the style of SpaceX. From this point of view, the total number of Starlink satellites currently planned to be launched by SpaceX is 840, which will not be far away.

The total number of Starlink satellites that can directly connect to mobile phones will reach 840

2G and 5G in the Space Age

Last year, Huawei's mobile phone became famous for its satellite calling function, which won a sensational effect in the market and reputation, and domestic manufacturers followed suit. BYD U8, as a high-end off-road vehicle, has also made its satellite calling function a major selling point - in the deserted wilderness, this is a real necessity. In the 618 of 2024, when Xiaomi Ultra was still comparing the antenna size with Huawei's satellite calling mobile phone, many people did not realize that the one who killed this generation of mobile phones might not be a stronger mobile phone, but a satellite.

Whether for Generation Z or users of other age groups, calls and text messages are the minimum demand, and data transmission is a high-level value-added demand. The focus of users is not on whether to connect through space-based satellites or ground base stations, but on the data transmission speed, latency and cost. You can't chat with Ge You in a lying position, watch Douyin/Tiktok, or play PUBG. The space-ground interconnection that can only realize satellite calls lacks usage scenarios except for emergency communications.

To put it in a less precise but more understandable way, Xiaomi Ultra and Huawei's satellite communication phones, or BYD U8, have brought us into the 2G/3G era of space-ground connectivity, while SpaceX's cellular Starlink system is trying to pull people into the 4G/5G era of mobile phone space-ground connectivity. There is no need to pick out words and technical definitions here, just an analogy for ease of understanding.

Musk released the actual speed of mobile phone direct connection to satellite

Xiaomi Ultra and Huawei's satellite call phones can make calls and send and receive text messages through China's Tiantong satellite. China Telecom Tianyi Cloud website announced that the maximum data bandwidth is 384kbps. On March 3, 2024, Musk posted a speed test on the social platform X, using an unmodified Samsung Android phone to directly connect to the Starlink satellite and transfer a 60.3MB file, which can reach a speed of 15.6Mbps to 17.2Mbps. On May 22, two SpaceX employees connected to the Starlink satellite directly connected to their mobile phones and demonstrated the video chat function.

SpaceX's first partner is T-Mobile, which transmits cellular data through the radio spectrum in the 1.91-1.995GHz frequency band. This fall, SpaceX will provide services to T-Mobile customers. In the initial stage, about 300 Starlink satellites directly connected to mobile phones are needed to provide users with a large enough coverage area. In addition to SpaceX, several other companies in the United States are also working to increase the satellite data download rate. Currently, the BlueWalker 3 satellite download rate can reach 10-14Mbps.

Samsung phones are one step ahead and can chat via satellite network video. This is not because Samsung phones are better than Xiaomi or Huawei's satellite calling phones, but mainly because they rely on the modified version of satellites.

SpaceX mobile phone directly connects to satellite, which is equivalent to moving the base station into space

Magic cell phone or magic satellite

China and the United States currently have different paths to achieve mobile phone-space interconnection: China chose to transform mobile phones, while the United States chose to transform satellites.

In a sense, Xiaomi and Huawei have achieved the interconnection between the sky and the earth by designing special chips and antennas to create modified mobile phones, which is equivalent to turning on the mobile phone plug-in. The advantage of this method is that it is quick and easy. At present, several major domestic mobile phone manufacturers cannot afford the high research and development costs of satellites, so it is more feasible to modify mobile phones. By modifying mobile phones to receive Tiantong satellite signals, only a few satellites can achieve coverage of the Asia-Pacific region.

One night in October 2023, SpaceX quietly launched a new "Starlink Direct to Cell" website page specifically for promoting its upcoming direct Starlink satellite service for mobile phones, with the slogan: "Let global LTE phones seamlessly access text, voice and data." SpaceX's new website added: "'Starlink Direct to Cell' can be used anywhere with an existing LTE phone connected to the sky. No hardware, firmware or special applications need to be changed to provide seamless access to text, voice and data."

The method SpaceX chose is to modify satellites to be compatible with mainstream mobile phone models on the market in order to "swallow the world". Samsung Galaxy, Apple iPhone and Google Pixel can all be directly connected to the cellular Starlink without modification. Starlink satellites that connect directly to mobile phones connect to the existing constellation via laser backhaul, using advanced modems on board as mobile phone signal towers in space.

Schematic diagram of the Tiantong-1 satellite, which features a large antenna

The short-term, quick and easy approach of domestic mobile phone manufacturers has gradually exposed obvious shortcomings. There is a huge gap in bandwidth capacity between the three Tiantong satellites and the 840 Starlink satellites that directly connect to mobile phones, resulting in slow data transmission speeds and high latency for users.

Tiantong-1 is a high-orbit (GEO) synchronous satellite, located at a fixed position about 36,000 kilometers above the Earth's equator, synchronized with the Earth's rotation. The construction of a high-orbit satellite system is relatively simple, and only three synchronous Earth satellites are needed to cover most areas except the poles, but the cost-effectiveness of operation and on-orbit maintenance is relatively high. At present, my country has launched three Tiantong-1 satellites and realized networking.

It is worth noting that the Tiantong-1 satellite is not specifically used to lay out the track of "space-ground network interconnection". Tiantong-1 satellite was put on the agenda after the "5.12" Wenchuan earthquake in 2008 and supported by the Prime Minister's Special Fund. Its primary task is to achieve emergency communications when my country suffers severe natural disasters.

The orbital altitude of low-orbit (LEO) communication satellites is 500 km to 2000 km. SpaceX Starlink, China Hongyun and China Hongyan, which were cancelled after testing, are all located in LEO orbits. Generally speaking, the round-trip delay of low-orbit communication satellite networks is generally less than 100ms, while the round-trip delay of high-orbit communication satellites will reach about 600ms. Therefore, from the perspective of orbital altitude, Tiantong's communication delay is inherently long. Friends who have played a few games of PUBG or King of Glory know what high latency means.

In December 2022, the Federal Communications Commission (FCC) approved SpaceX to operate 7,500 second-generation satellites at altitudes of 525, 530, and 535 kilometers (the same area as the first-generation satellites). In February 2024, SpaceX applied to the FCC to operate cellular second-generation Starlink satellites between 340 and 360 kilometers. Musk has continuously lowered the deployment altitude of Starlink satellites, striving to reduce latency to below 20ms. The lowering of the satellite orbit will increase resistance and shorten the life of the satellite, which will directly lead to higher costs, but Musk is confident that he has found a way to deal with the problem.

Magically modified mobile phones or magic modified satellites, the choice of path is based on the differences in infrastructure and communication application scenarios between the two countries. China's fiber-optic broadband network and 5G ground base stations are ahead of the United States, and 5G base stations have even been opened on Mount Everest and the Pamir Plateau. The improvement of the ground communication network has made China's demand for the deployment of space-based satellite networks small. On the contrary, the United States has a more urgent demand for space-based satellite cellular networks and wireless broadband in application scenarios.

But the road of modified mobile phones has an end, and we will eventually return to the road of modified satellites, which requires huge investment but has greater development potential.

The Hongyan constellation plans to launch its first test satellite in 2018, and there are no new launch plans since then.

How does China's Starlink respond?

"Only paranoids can survive", it is unexpected that this is not a law unique to Silicon Valley, Musk has also turned it into a law of aerospace. Launching satellites like planting potatoes, deploying more than 40,000 satellites in the sky to build a giant constellation, was criticized as a crazy plan at the time. But now the potatoes planted by Musk in space have taken root and sprouted and it is harvest season, from wireless broadband, to direct mobile phone connection, to high performance and low cost, the military has great potential for star shield. The butterfly's wings have spread, and I wonder what kind of waves it will set off.

Faced with Musk's relentless pressure, China's national team and private business teams have stepped in and are catching up. But it should be noted that with the introduction of policies and the entry of various funds, the Chinese version of Starlink is everywhere in the media and self-media reports. If it is a constellation, it dares to boast that it is the Chinese version of Starlink, without considering the scale and main purpose.

The rise of various versions of the Chinese version of Starlink reflects the country's enthusiasm for the development of space-based Internet, which may not be a completely bad thing. However, only by squeezing out the bubble, seeking truth from facts, and avoiding detours can we promote the rapid development of China's reusable rockets and Chinese version of Starlink satellites. The Chinese national team suspended the immature Hongyan and Hongyun projects, fully demonstrating its pragmatic attitude and full courage. Building Starlink requires huge investment and long-term efforts. Only by concentrating on doing big things can we have the opportunity to become bigger and stronger and create glory again.

Will users pay for the direct satellite connection to play games, video chat, surf the Internet, and download large files? In fact, 5G faced similar doubts at the beginning of commercial use. In fact, when the industry chain matures further and the cost is further reduced, satellite communication functions may become standard features of mobile phones like WIFI, deeply integrated into and changing our daily lives. Here is a small survey, and netizens can vote whether to buy or not. After a few years, remember to come back and check in, it will be more interesting.

How long will it take for domestic mobile phones to connect to the Internet directly via satellite? This is not a question that mobile phone manufacturers can answer. We are waiting for the answer from the real Chinese Starlink.

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