Rakuten Mobile proposal selected for Jaxa space strategy

As part of a project to enable “seamless” frequency sharing and handover between satellite and terrestrial networks, Rakuten Mobile today announced that its joint proposal with the University of Tokyo for dynamic frequency sharing technology has been selected by the Japan Aerospace Exploration Agency (Jaxa) for its Space Strategy Fund programme.

Jaxa’s Space Strategy Fund is designed to support multi-year technology development projects by private companies, startups and academic institutions in three key areas: transportation, satellites and related technologies, and exploration. The programme aims to expand markets, address societal challenges and “pioneer new frontiers”.

It is also designed to ensure uninterrupted connectivity for applications such as autonomous vehicles and drones, regardless of location. Research and development for the satellite and terrestrial network integration for seamless frequency sharing-themed project is eligible for up to ¥11bn (£53m) in funding. The project is planned to run between March 2026 and March 2031, and this period runs from the date of the funding grant decision through to the end of the fiscal year, in which the first stage-gate evaluation is completed.

The R&D behind the project aims to develop frequency-sharing technology for the handover between satellite communications and terrestrial wireless networks through artificial intelligence (AI)-based next-gen satellite communications.

The researchers note that in direct satellite-to-mobile communication, the same frequency bands are frequently shared with terrestrial networks, requiring interference management based on real-time conditions. Advanced correction is particularly crucial for voice and video calls due to Doppler effect and propagation delays.

Through AI-powered integration of satellite and terrestrial network operations, Rakuten says next-gen satellite communications AI will enable “seamless” connectivity, even as users transition between coverage areas. Additionally, it will look to demonstrate “strong” potential to support next-generation services that demand uninterrupted connectivity, including autonomous vehicles, flying cars and drones.

Rakuten Mobile and the University of Tokyo have a history of collaboration in AI-driven satellite communication research. This includes working on a virtualised Open RAN testing environment on the university campus and conducting joint R&D into ultra-wide internet of things (IoT) coverage utilising low Earth orbit (LEO) satellites.

The latter has seen Rakuten Mobile and the University of Tokyo build an IoT network using LEO satellite communications to establish use cases for IoT services using NB-IoT and LTE devices. This makes it possible to provide low-cost IoT services for various industries in locations that would typically be out of network coverage, such as mountainous areas, remote islands or on the sea.

Through the initiative, the two organisations say they will conduct verification tests for integrated satellite-terrestrial network operations using next-gen satellite communications AI.

The R&D will focus on developing next-gen satellite communications AI to monitor and control direct satellite-to-mobile communications and terrestrial networks sharing the same frequency bands. The goal is to avoid interference and improve operations and service quality for satellite direct communication.

The research will investigate AI-driven power control as well as interference management and traffic optimisation. Potential outcomes include development of an AI application to automatically power on and off satellite communication based on coverage data collected from both satellite and terrestrial base stations.

Additionally, the project will explore implementation of an AI application to manage interference mitigation, frequency adjustments and traffic load balancing. This is designed to ensure optimal connectivity during disasters, user transition and handover scenarios.