SoftBank Tests Dynamic Null-Forming for HAPS Networks

Tokyo, Japan – SoftBank Corp. announced it has demonstrated a dynamic null-forming technology intended to reduce radio frequency interference from Non-Terrestrial Networks (NTN), such as High Altitude Platform Stations (HAPS), to ground-based communication systems.

The field test was conducted in December 2025 over Hachijo-jima, Tokyo, using a light aircraft operating as an aerial base station.

According to SoftBank, the aircraft flew at an altitude of approximately 3,000 meters at speeds exceeding 200 kilometers per hour.

The company said the system used the 1.7 GHz frequency band to establish a wide communication area.

The dynamic null-forming technology controls the direction of nulls — zones where radio emission is suppressed — to adjust to the shifting position and attitude of an aircraft during flight.

The system uses beamforming to direct radio waves to devices connected to the aerial base station while suppressing emissions toward terrestrial base stations.

SoftBank reported that trial measurements indicated the technology improved the average throughput of devices connected to the ground base station by about 80 percent.

The company said the system maintained throughput stability despite the aircraft's continuous movement and turning, and that wide-area coverage can be provided from the sky without significantly degrading terrestrial network quality.

The test equipment included SoftBank's 5G-compatible cylinder antenna and a high-capacity communications payload.

The research was conducted as part of a 2023 project funded by the Beyond 5G (6G) Fund, commissioned by Japan's National Institute of Information and Communications Technology (NICT).

SoftBank said it plans to use the findings to advance the implementation of frequency-sharing technologies between NTNs and terrestrial communication networks.