Rakuten Mobile and JAXA Aim for Fusion of Space and Ground with Next-Generation Satellite Communication AI
Rakuten Mobile and JAXA Aim for Fusion of Space and Ground with Next-Generation Satellite Communication AI
Rakuten Mobile, Inc. has been selected for the Space Strategic Fund project by the Japan Aerospace Exploration Agency (JAXA). This technology development project is attracting attention as a groundbreaking initiative that utilizes artificial intelligence (AI) to seamlessly integrate satellite communications with terrestrial networks.
A project worth up to 11 billion yen begins
In the 'Development and Demonstration of Frequency Sharing Technology for Realizing Integrated Operation of Satellite Communications and Terrestrial Networks,' publicly solicited by JAXA as part of its Space Strategic Fund project, the dynamic frequency sharing technology development proposed by Rakuten Mobile was selected. The Nakao Laboratory at the Graduate School of Engineering, The University of Tokyo, is participating in this project as a collaborative institution, and the total support amount is a large-scale project of up to 11 billion yen.
The project period is scheduled for approximately five years from March 2026 to the end of March 2031, and is planned to proceed in stages through stage-gate reviews.
What is next-generation satellite communication AI?
The core of this research and development is the innovative technology known as next-generation satellite communication AI. This technology aims to develop frequency sharing technology that has the function of managing and controlling satellite communications via AI, and realizes smooth switching with terrestrial wireless communication networks. In 'satellite direct communication,' where low-Earth orbit satellites connect directly to commercially available smartphones, the same frequency bands as terrestrial networks are often shared, requiring advanced interference adjustment according to communication conditions. Especially in voice and video calls, complex correction processing is required due to the effects of Doppler shift (frequency changes due to satellite movement) and propagation delay.
Benefits of integrated operation by AI
Two major important functions will be implemented in the integrated operation by next-generation satellite communication AI. First, an application will be developed that allows AI to control the automatic suspension and activation of satellite communications based on area coverage information obtained from satellite communication and terrestrial network base station equipment. This will enable satellite communications to be operated only when and where necessary, allowing for efficient operation. Second, an application will be implemented that uses AI to control interference adjustment between satellite communications and terrestrial networks, frequency changes for satellite communications, and optimization of traffic accommodation. This will enable the automatic securing of an optimal communication environment in response to situations such as disasters or handovers caused by user movement.
Benefits for users
What specific benefits will general users receive once this technology is put into practical use? First, users will be able to maintain a stable and comfortable communication environment even when moving between network areas. Currently, communication can become unstable in places where terrestrial network coverage is interrupted, but through integrated operation by AI, satellite communications and terrestrial networks will automatically switch, realizing uninterrupted communication. Furthermore, this technology is expected to be utilized for next-generation services. For services that require constant connection, such as autonomous vehicles, flying cars, and drones, communication interruptions can be a fatal problem. Integrated operation by next-generation satellite communication AI has the potential to become a foundational technology that supports these future mobility services.
Cooperative relationship between Rakuten Mobile and the University of Tokyo
Rakuten Mobile and the University of Tokyo have a track record of conducting multiple joint research and development projects to date. In August 2022, they opened the 'Rakuten Mobile Open Innovation Lab' on the University of Tokyo campus, providing a verification environment for virtualized Open RAN technology. In addition, since November 2021, they have started joint research and development on IoT super-coverage using low-Earth orbit satellites, and have been continuously working on research and development related to the management and control of satellite communications by AI in Rakuten Mobile's network technology verification environment. This long-standing cooperative relationship and research track record are considered to be the background for the selection of this project. Through this research and development, both parties plan to conduct verification for the integrated operation of satellite communications and terrestrial networks using next-generation satellite communication AI.
Positioning of JAXA's Space Strategic Fund project
JAXA's Space Strategic Fund project is positioned as an important measure to promote the development of Japan's space industry. In the three fields of 'transportation,' 'satellites, etc.,' and 'exploration, etc.,' it supports private companies including startups and academic institutions such as universities over multiple years (up to 10 years) so that they can work on technology development aimed at market expansion, solving social issues, and frontier development. Rakuten Mobile's project falls under the 'satellites, etc.' field and is expected to be an initiative that accelerates the practical application and popularization of satellite communication technology.
Importance of frequency sharing technology
An important point in this research and development is frequency sharing technology. Radio waves are a finite resource, and frequency bands suitable for communication are particularly limited. To realize satellite direct communication using low-Earth orbit satellites, sharing the frequency bands used by existing terrestrial networks is a realistic option. However, if multiple communication systems using the same frequency interfere with each other, communication quality will drop significantly. Especially in satellite communications, interference avoidance with terrestrial networks has been considered an extremely difficult technical challenge because Doppler shift occurs due to the high-speed movement of satellites, and propagation delay occurs due to the long distance between the ground and the satellite. Next-generation satellite communication AI aims to solve these complex interference problems in real time and provide stable communication services even in frequency sharing environments.
Role as communication infrastructure during disasters
Integrated operation of satellite communications and terrestrial networks is expected to play an important role not only in improving convenience during normal times but also as communication infrastructure during disasters. When natural disasters such as large-scale earthquakes or typhoons occur, terrestrial communication infrastructure can be damaged, causing communication to be cut off. However, since satellite communications do not depend on terrestrial infrastructure, it is possible to maintain communication even during disasters. If integrated operation technology by next-generation satellite communication AI is established, it will be possible to automatically switch to satellite communications during disasters and secure communication in affected areas.
Contribution to the development of Japan's communication technology
Rakuten Mobile states that through this research and development, it will advance satellite communication networks, provide better network services to customers, and contribute to the development of Japan's communication technology. In recent years, the development competition for communication services utilizing low-Earth orbit satellites has intensified globally. Many companies, including SpaceX's Starlink, are proceeding with the construction of satellite constellations, and it is expected that satellite communications will become an important element of future communication infrastructure. In such an international competitive environment, advancing Japan's own technology development is extremely important for protecting the country's communication sovereignty and ensuring technological superiority. This project, through the cooperation of Rakuten Mobile, the University of Tokyo, and JAXA, can be said to be an initiative with the potential to push Japan's communication technology to the world's cutting edge.
Future outlook and stage-gate reviews
This research and development is scheduled to begin in March 2026, but periodic stage-gate reviews are set for the progress of the project. The initial subsidy project period will be from the date of the subsidy decision to the end of the fiscal year in which the first stage-gate evaluation ends, and subsequent extensions will be determined based on the results of the stage-gate evaluation. The total support amount of 11 billion yen is also an upper limit and may fluctuate due to future stage-gate reviews, etc. This is a mechanism to flexibly adjust support according to the progress and results of the project, and can be said to be a device for realizing effective research and development investment.
Summary
The next-generation satellite communication AI development project by Rakuten Mobile is a challenging initiative with the potential to significantly change the future of communication technology. By seamlessly integrating satellite communications and terrestrial networks through AI, users will be able to enjoy a stable communication environment wherever they are. In addition, the social impact brought about by this technology, such as next-generation mobility services like autonomous vehicles and flying cars, and securing communication during disasters, is immeasurable. After a five-year research and development period, what kind of results will be produced is highly anticipated. We hope that this project, through the collaboration of industry, academia, and government—Rakuten Mobile, the University of Tokyo, and JAXA—will raise Japan's communication technology to the world's most advanced level and make our lives richer and safer.
Personal Opinion and Consideration: The Future of Communication Infrastructure as Seen in Rakuten Mobile's Next-Generation Satellite Communication AI Development
The selection of Rakuten Mobile, Inc. for the JAXA Space Strategic Fund seems to go beyond the framework of a single company's technology development project and could lead to questions about the state of Japan's communication infrastructure and the entire social system. With large-scale support of up to 11 billion yen, the development of 'next-generation satellite communication AI' that integrates satellite communications and terrestrial networks with AI has begun, and I would like to deeply consider the meaning of this initiative from both technical and social aspects.
Possibility of a paradigm shift in communication infrastructure
First, what should be noted is that this project has the potential to change the conventional concept of communication infrastructure. Until now, terrestrial networks and satellite communications have been built and operated as separate systems. Terrestrial networks have been responsible for high-speed, large-capacity communication in urban and densely populated areas, while satellite communications have played a role in complementing areas where terrestrial infrastructure does not reach, such as the sea and mountainous areas. However, the integrated operation that Rakuten Mobile is aiming for has the goal of making these two function as one seamless network. According to the press release, it is stated that it will be able to 'provide a stable and comfortable communication environment even when users move between network areas,' and improvements in user experience are expected. This can be said to indicate a direction that shifts the concept of communication infrastructure from 'ground-centered' to 'space-ground integration'.
Possibilities brought about by AI control
The keyword 'next-generation satellite communication AI' is thought to have a deeper meaning than mere technical novelty. Conventionally, the control of communication networks has been performed mainly based on human operators or pre-set rules. However, in the integrated operation of satellites and terrestrial networks, as stated in the press release, it is necessary to simultaneously optimize extremely complex parameters that change in real time, such as Doppler shift, propagation delay, and interference adjustment. The approach of utilizing AI to deal with this complexity is considered one of the promising options. In the press release, it is stated that AI will 'control the automatic suspension and activation of satellite communications' and 'control interference adjustment, frequency changes, and traffic accommodation optimization with AI.' Thinking about securing communication during disasters, the press release states that it will 'secure an optimal communication environment in response to situations such as disasters or handovers caused by user movement.' Conventionally, depending on the situation, there were scenes where the impact lasted until restoration or where operational judgment by humans was required. If integrated operation by AI is realized, the range in which communication switching and operational adjustments can be automated in response to situational changes may expand. It is expected as a technology that can contribute to securing important communications including emergency calls, but the actual performance and operational form are expected to become clear after demonstration.
Technical difficulties and challenges of frequency sharing technology
One of the important technical challenges in this project is thought to be frequency sharing technology. In order for terrestrial networks and satellite communications to share the finite resource of radio waves, advanced interference control is required. According to the press release, it is stated that 'in communication methods where low-Earth orbit satellites connect directly to commercially available smartphones, it is often assumed that the same frequency band as terrestrial networks is shared, and interference adjustment according to communication conditions is necessary.' In particular, because low-Earth orbit satellites move at high speeds, the transmission frequency changes due to Doppler shift, and propagation delay of radio waves due to the distance between the ground and the satellite also occurs. The press release also points out that 'in voice and video calls, advanced correction processing is required due to the effects of Doppler shift and propagation delay.' Integrated control by AI may be a promising approach to this difficult problem. Generally, if machine learning technology is utilized, it is expected to predict future situations from past data or solve complex optimization problems. However, what specific AI technology or machine learning method will be adopted is not stated in the press release and is thought to be decided during future technology development. If this technology is established, precious resources called frequencies can be utilized more efficiently, and a situation that is beneficial to both sides—operational optimization for communication carriers and improved communication quality for users—may be created.
Strategic positioning of the company Rakuten Mobile
In the background of Rakuten Mobile working on this project, the company's unique corporate strategy can be seen. As a late-coming new entrant in the Japanese mobile phone market, Rakuten Mobile has developed its business with a different approach from existing major carriers. Fully virtualized network, adoption of Open RAN, cloud-native architecture. From the beginning, Rakuten Mobile has adopted a technology strategy that is distinct from conventional carriers. This initiative in satellite communications is also thought to be on this extension. Existing major carriers have vast assets of terrestrial networks that they have built over many years. While this is a strength, it is said that there are aspects where various considerations are required for fundamental technological transformation because the investment in existing infrastructure is large. On the other hand, because Rakuten Mobile is a relatively new company, it can also be seen that it is in a position where it is easier to challenge new technologies. The ambitious goal of integrating satellite communications and terrestrial networks can be said to symbolize Rakuten Mobile's technology-oriented stance. If successful, it could become a differentiator in the telecommunications industry, and the technology and know-how acquired in the development process could have value in future business development.
Structure of the industry-academia-government collaboration model
What should be noted in this project is the industry-academia-government collaboration structure of Rakuten Mobile (industry), the University of Tokyo (academia), and JAXA (government). According to the press release, Rakuten Mobile and the University of Tokyo have a track record of conducting continuous joint research since 2021, and have worked on 'joint research and development on IoT super-coverage using low-Earth orbit satellites' and 'technical verification of virtualized Open RAN.' In Japan, the importance of industry-academia-government collaboration has been called for for many years, but in reality, there have been many cases where it was difficult to build an effective cooperative relationship due to differences in the interests and cultures of each party. However, this project is a collaboration formed after building a step-by-step cooperative relationship over several years, and it is thought to have continuity that is different from one-off cooperation. The Nakao Laboratory at the Graduate School of Engineering, The University of Tokyo, is participating in the project as a collaborative institution as a laboratory that conducts research in the field of network technology, and by combining the academic knowledge of the laboratory, the practical network operation experience of Rakuten Mobile, and the expertise in space technology of JAXA, synergistic effects can be expected. In addition, the support scale of up to 11 billion yen has a certain scale to work consistently from basic research to demonstration experiments. According to the press release, the implementation period is scheduled for approximately five years from March 2026 to the end of March 2031, and time is secured to carefully polish the technology.
Expectations for next-generation mobility services
As a field where the results of this project will be utilized, the press release states that 'utilization for next-generation services that require constant connection, such as autonomous vehicles, flying cars, and drones, can also be expected.' Communication stability is considered an important element for these services. For example, let's think about autonomous vehicles. If advanced autonomous driving is realized in the future, it is assumed that the vehicle will always be connected to the network and acquire and transmit information in real time. At this time, if communication is cut off in places where terrestrial network coverage is interrupted, such as inside tunnels or in mountainous areas, it may affect the operation of the system. If integrated operation of satellite communications and terrestrial networks is realized, it may be possible for vehicles to maintain a communication environment over a wider range. However, what level of quality and availability the 'stable and comfortable communication environment' in the press release specifically means is expected to become clear after demonstration. The same applies to flying cars and drones. Since these literally move in the air, there is a possibility that there are challenges in securing communication areas only with terrestrial base stations, and it is thought that combination with satellite communications can be effective. This project can be said to indicate the direction of building a communication infrastructure that supports future means of transportation.
Japan's initiatives in global competition
In the field of satellite communications, the development of communication services utilizing low-Earth orbit satellites is currently progressing overseas, and international competition is unfolding. Multiple companies and organizations are proceeding with the construction of their own satellite constellations, and the satellite communication market is in an active situation. Under such circumstances, what is the significance of Japan advancing its own technology development? One perspective is the direction of technological differentiation. Some existing satellite communication services require dedicated terminals. However, according to the press release, the 'satellite direct communication' that Rakuten Mobile is aiming for is stated as a 'communication method where low-Earth orbit satellites connect directly to commercially available smartphones.' If dedicated terminals become unnecessary, it could lead to improved user convenience and lower hurdles for introduction. Furthermore, what is emphasized in the press release is the point that 'AI will integrally operate satellite communications and terrestrial networks.' This is one technical approach and is thought to indicate a direction for differentiation. As another perspective, some think that it has a certain significance from the viewpoint of the autonomy of communication infrastructure. Communication infrastructure is an important social foundation that supports the roots of economic and social activities. Advancing technology development domestically could lead to maintaining and developing knowledge and capabilities regarding such foundations. In particular, securing communication during disasters and emergencies is also important from the viewpoint of crisis management. Having a technology foundation developed domestically may expand the options for responding to such situations.
Points to consider in social implementation
On the other hand, at the stage where this project is actually implemented in society, several challenges and considerations are assumed. First is the viewpoint of cost. Launching and operating low-Earth orbit satellites costs a corresponding amount. While the 11 billion yen support at the research and development stage is important, further investment may be necessary at the stage of actually deploying the service. Building a business model that can provide services at a price acceptable to users while assuming this investment will be a challenge. Next is the viewpoint of regulations and systems. Generally, in order to realize frequency sharing, consistency with related laws and regulations, including the Radio Act, can be a point of discussion. Even if it is technically possible, there are cases where adjustments in the system aspect are necessary. It is thought that it will be important to proceed with dialogue with related organizations in parallel with technology development. Also, consideration regarding the handling of data is important. In integrated operation of networks, there is a possibility of handling various network data operationally. It will be important that such data is appropriately protected and that a design that considers privacy is made. Furthermore, the viewpoint of international cooperation is also a point to be considered. Since low-Earth orbit satellites move across national borders, there are cases where harmony with international frameworks is necessary in frequency adjustment and orbital management. How to achieve consistency with international standards and rules while advancing Japan's own technology development is a challenge to be considered.
A step toward the future of communication technology
The next-generation satellite communication AI development project by Rakuten Mobile, JAXA, and the University of Tokyo is a technical challenge and at the same time can be said to indicate one direction for the future of communication infrastructure. The expressions 'stable and comfortable communication environment' and 'utilization for next-generation services that require constant connection' in the press release indicate a goal of realizing more stable communication over a wider range. Communication technology is not an end in itself, but a means to support people's lives and make society better. The integrated operation aimed at by next-generation satellite communication AI is thought to indicate one approach to the question of how technology can contribute to society. Five years from now, it is impossible to predict with certainty what results this project will have produced. However, it is expected that this challenge will contribute to the development of Japan's communication technology and become a step toward the realization of a better communication environment. And whether it is a success or a result with remaining challenges, I hope that the knowledge and experience gained from this initiative will contribute to the development of Japan's science and technology and be passed on to the next generation.
Rakuten Mobile's technology development proposal selected for JAXA Space Strategic Fund
https://corp.mobile.rakuten.co.jp/news/press/2026/0216_01/
