Nippon Telegraph and Telephone Corporation (NTT) and the Japan Aerospace Exploration Agency (JAXA) have begun steady-state, in-orbit testing of a satellite system that combines satellite MIMO communication and satellite-based IoT sensing. The testing is being conducted on a scale model named the Low Earth Orbit (LEO) satellite MIMO/IoT transmission system (LEOMI). Initial results confirm that the technology is working as expected in space, and a demonstration will be done at Tsukuba Forum 2026 on May 27–28, 2026.
Multiple input and Multiple output (MIMO) technology uses multiple antennas on the satellite to transmit multiple data streams simultaneously to ground stations. Signals received at multiple ground antennas are combined and processed to separate data streams. The goal of this testing is to verify increased transmission capacity between LEO satellites and ground stations under real orbital conditions. The system also tests the ability of satellites to receive signals directly from multiple low-power IoT devices operating in the 920 MHz band.
On March 13, 2026, the first steady-state MIMO transmission experiment was conducted. Two different data streams stored onboard LEOMI were transmitted at the same frequency using two antennas. After reception at two ground stations, signal processing was applied to separate the streams. Analysis showed that interference between signals was successfully compensated, confirming that satellite MIMO signal processing worked as intended.
This technology would eliminate the need for terrestrial network infrastructure or ground stations, making it possible for IoT devices to operate in remote locations such as oceans, mountains, and disaster-affected regions. NTT and JAXA aim to confirm that satellite-connected IoT devices can achieve battery life comparable to devices connected through ground-based networks.
Applying these technologies to observation satellites could improve the resolution and volume of image and radar data, supporting more accurate weather forecasting, disaster prediction, terrain monitoring, and ocean observation. If successful, the approach could support large-scale deployment of low-cost IoT services, including infrastructure monitoring, environmental observation, and smart metering, in areas where building communication networks is impractical or impossible.
LEOMI is a scale model, a smaller version designed for onboard use in small demonstration satellites to validate technologies under actual orbital conditions. It is installed on the RAISE-4 experimental satellite, launched on December 14, 2025, carrying eight experimental payloads, including LEOMI. The system has transitioned to full steady-state operations, and the testing is expected to continue for a year.
The LEOMI demonstration is part of Japan’s Innovative Satellite Technology Demonstration Program. NTT and JAXA have been conducting joint research since 2019. The partnership aims to integrate advanced wireless and optical communication technologies with spacecraft systems to create secure, high-capacity networks linking space and terrestrial infrastructure.
