An Era of Controlling Cars from Satellites? The Battle for Supremacy in In-Vehicle Satellite Communication

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Are you familiar with the term 'flying base stations'? It is an idea to cover areas that cannot be fully covered by ground base stations, such as mountainous regions and remote islands, by placing a base station in the sky to cover a wide area with a single unit. SpaceX, led by Tesla CEO Elon Musk, has launched more communication satellites called Starlink than anyone else in the world, boasting the world's highest global coverage rate. In the near future, smartphone signals may never go out of range again.
This satellite communication service has already been launched for smartphones by companies like au. Furthermore, development is accelerating globally for technology that goes beyond positioning like GPS to perform high-precision communication for things like autonomous driving via these flying base stations.
By reading this article, I believe you will understand not only the competition in developing flying base stations but also the technical hurdles of using satellite communication for autonomous driving and similar applications.

Executive Summary

1. GEO, LEO, and HAPS are components of Non-Terrestrial Networks (NTN) that each have different altitudes and characteristics.

Geostationary Earth Orbit (GEO) satellites cover a vast range from an altitude of about 36,000 km and are used for broadcasting, but they face the challenge of high communication latency. Low Earth Orbit (LEO) satellites orbit at altitudes from several hundred to several thousand kilometers, realizing low-latency, high-speed communication, but they require a constellation composed of many satellites. High Altitude Platform Stations (HAPS) are characterized by their ability to communicate directly with smartphones on the ground from the stratosphere at an altitude of about 20 km with even lower latency. By building a multi-layered network that integrates these, it is expected that a seamless and robust communication infrastructure will be realized that leverages the strengths of each while compensating for their weaknesses.

2. Satellite communication for smartphones is a technology that enables direct-to-device communication without special modifications by giving satellites the functions of mobile phone base stations and utilizing existing ground frequency bands.

In Japan, KDDI has partnered with SpaceX of the U.S. to launch a text messaging service ahead of others as 'au Starlink Direct.' Rakuten Mobile has teamed up with AST SpaceMobile of the U.S. and has succeeded in a demonstration experiment for video calls. SoftBank and NTT Docomo are also planning to start services in 2026, and currently, the focus is on messaging. Nevertheless, competition is intensifying to realize voice calls and broadband-class data communication in the future.

3. Starlink provides services in over 100 markets, including major developed countries such as North America, Europe, Japan, and Australia, boasting an overwhelming global coverage rate.

On the other hand, services are not provided in countries and regions such as China and Russia where government approval cannot be obtained for security reasons. The bandwidth per current second-generation satellite is estimated to be about 80-96 Gbps, but this is insufficient for future needs such as VR/AR and the connection of massive numbers of IoT devices. To address this challenge, Starlink is developing third-generation satellites with a capacity of 1 Tbps, about 10 times that of a single unit, with a strategy to meet future demand increases through qualitative improvements in satellites.

4. As Starlink sweeps the market, Japanese telecommunications carriers are taking a more multifaceted and strategic approach rather than simple competition.

While SoftBank resells Starlink's corporate services, it is aiming for the 'orchestration' of a multi-layered network that combines the B2B-strong UK-based OneWeb and its own HAPS. NTT is partnering with Amazon's Project Kuiper, a direct competitor to Starlink, and is also envisioning the construction of a next-generation infrastructure called the 'Innovative Optical and Wireless Network (IOWN),' which performs data processing in space by utilizing its own optical technology. As I had thought, while acting as both a partner and an intermediary to competitors, each company is pursuing its own unique added value.

5. To popularize satellite communication in high-speed moving objects like automobiles, several technical challenges must be overcome.

First, a low-profile electronically scanned phased array antenna that has low air resistance and can track the wide sky at high speed is essential, but its cost is a major challenge. Next, advanced signal processing capability is required for communication chips to correct frequency shifts caused by the Doppler effect associated with high-speed movement in real-time. Furthermore, seamless handover technology that switches without interruption between LEO satellites that change every few minutes, and between satellite communication and ground 5G networks, is directly linked to communication stability. Establishing secure and highly reliable communication protocols and software to integrate this hardware and software and link it with systems where safety is the top priority, such as Advanced Driver Assistance Systems (ADAS) and V2X (vehicle-to-everything) communication, is an urgent task.

6. Regarding the technical challenges of automotive satellite communication, distinctive research and development is progressing in various regions around the world.

In China, the automaker Geely is building its own satellite constellation and promoting a vertically integrated model that realizes the centimeter-level high-precision positioning essential for autonomous driving. In Europe, the Fraunhofer Institute in Germany, with the support of the ESA (European Space Agency), is developing fundamental technologies such as antennas and communication protocols, aiming to form an open ecosystem. In the U.S., Kymeta has commercialized electronically scanned flat-panel antennas specialized for vehicle mounting and is leading the commercialization of specific technologies, such as by conducting demonstration experiments with Toyota and others. In Japan, JAXA and NICT are taking the lead, focusing on more fundamental and advanced research and development, such as optical inter-satellite communication that forms the backbone of future communication systems and digital beamforming technology that flexibly allocates resources according to demand.

【① What are GEO, LEO, and HAPS?】

Non-Terrestrial Networks, commonly known as NTN, are a collective term for communication technologies that utilize outer space or the stratosphere to complement or expand terrestrial communication networks.
This is primarily composed of three elements at different altitudes: Geostationary Earth Orbit (GEO) satellites, Low Earth Orbit (LEO) satellites, and
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High Altitude Platform Stations (HAPS)
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by which it is constituted.
● Geostationary Earth Orbit (GEO)
These are located in a geostationary orbit far above the Earth, approximately 36,000 km from the ground.
Their role is to leverage the characteristic of appearing stationary from the ground by orbiting at the same speed as the Earth's rotation. Thanks to this, it is possible to constantly cover a wide area of the Earth with just a few satellites. They are mainly used for television broadcasting, meteorological observation, and as stable wide-area communication backhaul lines.
The required specifications include high reliability capable of withstanding long-term operation of 15 years or more. On the other hand, since the distance from the ground is very far, the biggest challenge is the high communication latency.
● Low Earth Orbit (LEO)
These orbit at a low altitude of 200 km to 2,000 km from the ground. For example, SpaceX's Starlink in the United States operates at an altitude of approximately 550 km.
As for their role, because they are close to the ground, communication latency is dramatically lower compared to GEO, enabling high-speed data communication. This aims to provide broadband internet services comparable to fiber optics to every corner of the Earth, including mountainous areas, the ocean, and inside aircraft, where it has been difficult to provide service until now.
When considering the required specifications, the range that a single satellite can cover is limited because it orbits the Earth at high speed. Therefore, to maintain a state where satellites are always overhead, it is essential to build a "satellite constellation" (a system where numerous satellites are linked and operated as a single unit). Advanced technologies such as inter-satellite optical communication (a technology that connects satellites with laser beams to perform large-capacity communication) are also required.
● High Altitude Platform Station (HAPS)
These fly in the stratosphere about 20 km from the ground.Their role is often called a "flying base station," acting as an intermediary between satellites and ground base stations. Because they are even closer to the ground than LEO, the latency is extremely low. And the biggest feature is that they can communicate directly with general smartphones without the need for dedicated antennas or terminals. One unit covers an area with a radius of 50 to 100 km, making it suitable for securing emergency communication networks during disasters or pinpointing gaps in communication areas in specific regions.The required specifications are long-term flight capability on the order of months using solar power generation, etc. They have the advantage of being easier to launch and update than satellites, and the costs are also lower.These GEO, LEO, and HAPS do not simply compete. In fact, it is believed that the future lies in linking them together to build a seamless integrated network.For example, roles can be divided to leverage each strength, such as GEO handling backbone communication, LEO providing high-speed access to users, and HAPS covering specific high-density areas like urban centers or event venues. This is expected to realize a more robust and reliable communication infrastructure.

【② Mechanism and Current Status of Smartphone Satellite Communication】

Satellite communication for smartphones is realized through technologies called "Direct-to-Device (D2D)" or "Direct-to-Cell." This is a groundbreaking mechanism that does not require the conventional dedicated large antennas or special terminals, but rather allows commercially available smartphones to communicate directly with Low Earth Orbit (LEO) satellites.
● Communication Mechanism
First, LEO satellites that provide the service are equipped with advanced eNodeB modems (communication devices with the main functions of LTE base stations) that have the same functions as terrestrial mobile phone base stations. This allows the satellite to function as if it were a "base station moving in outer space."
The key to this technology lies in using the same frequency bands as LTE and 5G used in terrestrial mobile phones. Thanks to this, the smartphone side does not require hardware or firmware changes or the installation of special apps, and communication with satellites becomes possible with existing terminals.
However, smartphone antennas have weak output and are very small. To capture these weak radio waves in outer space and deliver radio waves from the satellite to the smartphone, the satellite side is equipped with a very powerful large phased array antenna (an antenna that aligns many small antennas to electronically control the direction of radio waves). This antenna uses "beamforming" (a technology that concentrates radio waves in a specific direction for transmission and reception) to accurately target and establish communication with smartphones on the ground.
Then, after the satellite communicates with the user's smartphone, it transfers the data to a ground station (gateway) (a facility that receives radio waves from the satellite and connects to the terrestrial network). The ground station is connected to the mobile carrier's core network, from which it connects to the internet. From the user's perspective, the service will likely be provided in a manner similar to roaming with a local carrier when abroad.
● Trends and Realization Levels of Domestic Telecommunications Companies
KDDI (au), a pioneer in the Japanese market, partnered with SpaceX in the United States to launch "au Starlink Direct" in April 2025. It started with text message transmission/reception such as SMS and iMessage and location sharing, and now data communication with some apps is also possible.
Rakuten Mobile is partnering with AST SpaceMobile in the United States to promote the "SpaceMobile" project. In April 2025, they announced that they had succeeded in a video call experiment between commercially available smartphones, and it can be said that they are ahead in realizing high-bandwidth communication. They aim for commercialization as "Rakuten Saikyo Satellite Service" in the fourth quarter of 2026.
SoftBank has stated that it will start a direct communication service with smartphones in 2026, in parallel with investments in HAPS and OneWeb in the UK. Although the partner has not been disclosed, I believe Starlink is considered a strong candidate.
NTT Docomo is also aiming to start service in the summer of 2026, and is said to be in a similar situation to SoftBank.
The communication level currently realized is text messaging provided by KDDI, which is the first step toward commercialization. With the success of the demonstration experiment by Rakuten Mobile and AST SpaceMobile, it has been shown that rich data communication such as video viewing and ChatGPT is technically possible in the future. Each company plans to launch services by 2026, and service competition within Japan is expected to intensify in the future.

【③ Starlink's Global Coverage and Capacity Analysis】

Starlink, deployed by SpaceX in the United States, has an overwhelming presence in the Low Earth Orbit (LEO) satellite communication market, and its global deployment and communication capacity are unmatched.
● Global Coverage
As of mid-2025, Starlink officially provides services in over 100 countries and markets around the world, including Japan, the United States, Canada, most of Europe, Australia, and Brazil. The number of users exceeds 7 million worldwide, and it is spreading rapidly, especially in developed countries and countries with vast territories.
On the other hand, services are not provided in countries such as China, Russia, India, and Iran. Also, in some regions of Africa, the Middle East, and Asia, the situation remains one of waiting for approval from government regulatory authorities.
Now, the main reason why Starlink cannot be used is not a technical problem. In fact, it is caused by each country's political and regulatory barriers. Especially in countries like China and Russia, services have likely not been approved due to security concerns regarding the spread of communication infrastructure managed by foreign companies within the country. In other countries, reasons include the protection of the domestic telecommunications industry and delays in the approval process.
● Capacity per Communication Satellite and Future Needs
The number of users that one satellite can process simultaneously depends on the total bandwidth of the satellite, that is, throughput. The total bandwidth of the currently mainstream second-generation (Gen2) satellites is estimated to be approximately 80 to 96 Gbps per unit. This is equivalent to about four times the capacity of first-generation satellites.
Even so, it cannot be said to be sufficient for future needs. One satellite covers a cell of about 24 km square, but considering the communication demand that will be required in this area in the future, such as the use of VR/AR content by many users and constant connection from a vast number of connected cars and IoT devices, the capacity of current Gen2 satellites is significantly insufficient. Starlink is already limiting the number of users per cell to avoid "congestion" (a situation where communication lines are crowded and difficult to connect) in areas with high user density. The global satellite communication market is projected to grow to more than twice its current size by 2033, and an explosive increase in demand is certain.
To solve this capacity shortage, Starlink is developing next-generation third-generation (Gen3) satellites. Gen3 satellites aim for an overwhelming performance improvement of more than 10 times that of Gen2, with a downlink communication capacity of 1 Tbps (1,000 Gbps) or more per unit. If a communication demand of 1 Tbps occurs in one coverage area in the future, 12 to 13 Gen2 satellites would be required, but with a Gen3 satellite, it could be handled by just one. I believe Starlink's strategy is to anticipate future demand not just by increasing the number of satellites, but by a "qualitative shift" that dramatically improves the performance of the satellites themselves.

【④ Satellite Strategies of Major Telecommunications Carriers Competing with Starlink】

While Starlink has built an overwhelming lead in the consumer market, major telecommunications carriers such as SoftBank and NTT are not faced with a binary choice of simply launching satellites that compete with Starlink or becoming an intermediary for Starlink. While the hypothesis I formed has some points that hit the mark, in reality, they are developing even more advanced and multifaceted strategies.
● SoftBank: "Integrator/Controller" of Multi-Layer Networks
SoftBank's strategy is based on the "Ubiquitous Transformation (UTX)" concept, which positions itself not as a provider of a single means of communication, but as a platformer that integrates all communication layers and optimally controls them (orchestration: integrating multiple systems and linking them to operate optimally).
They have partnered with OneWeb in the UK, which has strengths in corporate (B2B) services and provides communication quality assurance. This can be said to be a complementary strategy that targets a different market from Starlink, which is centered on consumers (B2C).
On the other hand, to meet specific needs that require high-speed, low-latency communication, they are also reselling "Starlink Business," cleverly utilizing Starlink as part of their own service portfolio.
Furthermore, they are promoting HAPS, which flies unmanned aircraft in the stratosphere, building a unique strength that can communicate directly with smartphones with lower latency than satellites.
In conclusion, SoftBank is executing both sides of the hypothesis: partnering with a competitor to Starlink (OneWeb) while also acting as an intermediary for Starlink. However, its essence lies in establishing a position as an "integrator/controller" that seamlessly bundles these multiple Non-Terrestrial Networks (NTN) with its own terrestrial network and automatically provides the optimal communication means according to customer needs.
● NTT: "Builder" of Next-Generation Space Infrastructure
NTT's strategy is even more long-term and ambitious. Through "Space Compass," a joint venture with SKY Perfect JSAT, they have put forward the "Space Integrated Computing Network" concept.
First, they have formed a strategic partnership with Amazon's "Project Kuiper" in the United States, which is seen as Starlink's biggest rival, to jointly promote service deployment in Japan. This is positioned as a direct countermeasure to Starlink.
However, the core of NTT's strategy goes beyond mere provision of communication services. They are attempting to build data centers on geostationary (GEO) satellites by utilizing their own next-generation optical technology, "IOWN" (a next-generation communication infrastructure concept based on optical technology). And it is a grand concept of performing optical communication between satellites to complete data processing in outer space and sending only the necessary results to the ground. Doesn't this concept sound exciting? By doing this, they aim to dramatically reduce communication latency and the load on ground equipment.
In conclusion, NTT belongs to the camp that is launching satellites (Kuiper) that will compete with Starlink, but its ultimate goal can be said to be a more fundamental technological innovation that expands the communication infrastructure itself into space and creates a new form of computing.

【⑤ Technical Challenges of Satellite Communication in High-Speed Moving Objects (Automobiles)】

To introduce satellite communication to platforms like automobiles that move at high speeds and require constant communication reliability, it is necessary to overcome technical challenges that are incomparably more complex and diverse than services for stationary users. It is essential that antennas, semiconductors, communication protocols, and software all function as one.
● Antenna Technology: Balancing Low Profile and High-Speed Tracking
Conventional parabolic antennas are completely unsuitable for mounting on automobiles due to their shape and mechanical moving parts. Vehicles require a low-profile shape that has low air resistance and does not impair design, while also having the performance to instantly keep tracking LEO satellites moving at high speeds overhead.
Solving this difficult problem is the electronically scanned phased array antenna (a flat antenna that can electronically control the direction of radio waves without mechanical moving parts). However, this antenna is extremely high-cost, and a drastic price reduction is essential for widespread adoption in the automotive market. Also, vehicle body design and manufacturing technology that beautifully integrates the antenna into the vehicle roof or glass will be a major challenge. Furthermore, to keep tracking satellites even when the vehicle is turning or driving on slopes, wide-angle beam scanning capability that covers a wide range from the horizon to the zenith is also required.
● Communication Continuity: Seamless Handover
For LEO satellites, the time one unit is visible overhead is only a few minutes. Automobiles driving on highways must repeat "inter-satellite handover," which establishes a connection with the next satellite and seamlessly takes over communication, at a high frequency like a relay runner within this short time. Furthermore, when entering urban areas where terrestrial 5G networks become available, a smooth switch from satellite communication to the terrestrial network, or vice versa (inter-system handover), is also necessary.
For this, advanced control software using a "make-before-break" method that predicts the orbit of the next satellite and establishes the next connection before the current connection is cut is essential. Slight latency or packet loss in this handover process could become a fatal problem for Advanced Driver Assistance Systems (ADAS) or real-time V2X communication.
● Signal Stability: Dealing with the Doppler Effect
Between an automobile traveling at 100 km/h and a LEO satellite moving at 7 km/s or more, a "very large frequency shift (Doppler effect)" occurs. It is the same phenomenon as the sound of an ambulance siren changing when it approaches and when it moves away, right?
Stable communication cannot be maintained unless the communication chip (modem) mounted on the vehicle precisely calculates and continuously corrects this frequency shift in real time. This requires the development of dedicated semiconductors with powerful signal processing capabilities. If the correction is inaccurate, the communication link will be cut off immediately.
● Protocols and Software: Integration of the Entire System
Satellite communication systems do not function in isolation. They need to be safely integrated with various networks within the vehicle, such as V2X (vehicle-to-vehicle/vehicle-to-infrastructure communication), ADAS, and infotainment systems.
Intelligent communication protocols and middleware that absorb the latency fluctuations and handovers unique to satellite communication and present them to the in-vehicle application side as a single, always-stable communication line are important. In particular, the role of software that dynamically manages and prioritizes communication traffic, such as ensuring data communication for safety control systems as the highest priority and temporarily buffering data for entertainment systems, becomes extremely large. Of course, ensuring cybersecurity is also one of the most important issues.

【⑥ Global Research and Development Trends for the Challenges in ⑤】

Regarding the technical challenges of satellite communication for automobiles, research and development are progressing in major regions of the world with unique approaches that reflect their respective industrial structures and national strategies.
● China: Building an Autonomous Driving Ecosystem through Vertical Integration
A representative example is Geely in China and its subsidiary Geespace.
Geely, a major Chinese automaker, is not relying on other companies' satellite services, but is designing, manufacturing, and launching its own low-orbit satellite constellation, "Geespace." The core of this strategy is to provide centimeter-level high-precision positioning information and highly reliable communication, which are essential for realizing Level 4 autonomous driving to be mounted on its own brand of cars, under its own management. This is a "vertical integration model" that completes everything from automobiles to satellites and ground stations in-house, and can be said to be part of a national strategy to seize hegemony in the next-generation technology of autonomous driving.
● Europe: Industry-Academia-Government Collaboration Aiming for an Open Ecosystem
Representative examples in Europe are the Fraunhofer Institute for Integrated Circuits (Fraunhofer IIS) in Germany and the European Space Agency (ESA).
Fraunhofer, one of the world's top research institutions that Germany boasts, is leading research and development of fundamental technologies that are not biased toward specific products, such as intelligent antenna systems that form the foundation of satellite communication for automobiles, communication protocols that integrate 5G/6G and satellites, and V2X communication technology. Supporting this is ESA's ARTES program. Through public-private partnerships, they provide funding and technical support so that European companies can conduct technology development in a wide range of fields, from antenna components to communication services. This approach aims to build an open ecosystem that enhances the industrial competitiveness of Europe as a whole, rather than making a specific company win.
● United States: Market-Driven Approach Leading the Commercialization of Specific Technologies
A representative example in the United States would be Kymeta Corporation.
Kymeta specializes in the development and commercialization of flat-panel antennas using electronic beam steering, which are the most important key devices for satellite communication for mobile objects including automobiles. The company's antenna, "Kymeta u8," is a product without moving parts controlled by software, and it has already been introduced to the market. They are practicing a horizontal division of labor model where they collaborate with various players in the industry, centering on their core technology, such as conducting in-vehicle demonstration experiments jointly with Toyota Motor Corporation and partnering with OneWeb in the UK to start services for maritime use. This is a pragmatic approach typical of the United States, which is to quickly commercialize specific promising technologies and create markets.
● Japan: Advanced and Basic Research Carrying the Foundation of the Next Generation
Now, Japan's approach focuses on research and development of more advanced and difficult basic technologies that will be essential for future satellite communication systems, rather than immediate commercialization.
Specifically, these include optical inter-satellite communication technology that dramatically increases the communication capacity of satellite constellations, digital beamforming technology (technology that flexibly forms and controls radio wave beams using digital signal processing) that flexibly allocates radio waves to areas where communication demand is concentrated during disasters, and high-precision positioning and orbit control technology utilizing the Quasi-Zenith Satellite System "Michibiki." Also, attempts to innovate the manufacturing process itself, such as research on antenna 3D printing technology in outer space by Mitsubishi Electric, are being made. This can be said to be a long-term national strategy to accumulate intellectual property to seize future technological hegemony.