SoftBank Tests Tech to Enable NTNs to Share Spectrum with Mobile

Why It Matters

By enabling real‑time spectrum sharing between aerial and terrestrial networks, the technology reduces the need for dedicated frequency blocks, lowering deployment costs and accelerating rollout of connectivity solutions in underserved regions. This capability also positions SoftBank to compete in the emerging non‑terrestrial network market.

Key Takeaways

• Dynamic null‑forming suppresses aerial signals toward ground base stations.
• Test used 1.7 GHz band, 3,000 m altitude, 200 km/h speed.
• Successful interference mitigation paves way for spectrum sharing with terrestrial networks.
• Supports SoftBank’s 2026 pre‑commercial HAPS launch for remote connectivity.
• Technology applicable to other non‑terrestrial networks, enhancing overall spectrum efficiency.

Pulse Analysis

High‑altitude platform stations (HAPS) have long promised broadband coverage beyond the reach of traditional cell towers, but the biggest technical hurdle has been spectrum coexistence. Mobile operators must avoid harmful interference when an aerial base station operates on the same frequencies as ground networks. SoftBank’s recent field test introduced a dynamic null‑forming antenna that actively steers a radio‑frequency null toward terrestrial sites, effectively carving out a silent zone in the sky. This approach mirrors beam‑forming used in 5G but flips the focus to suppress, not enhance, emissions, allowing both layers of infrastructure to coexist on the 1.7 GHz band.

The trial’s parameters—3,000 meters altitude, speeds exceeding 200 km/h, and real‑time null adjustment—demonstrate that the system can adapt to the rapid positional changes inherent to airborne platforms. By maintaining interference below thresholds defined by regulators, operators can reuse existing spectrum allocations rather than acquiring costly new bands. This efficiency aligns with global spectrum policy trends that encourage shared use, especially as the International Telecommunication Union pushes for more flexible NTN frameworks. Moreover, the technology’s scalability means it could be retrofitted to other non‑terrestrial assets such as low‑Earth‑orbit satellites or tethered balloons, broadening its market relevance.

For SoftBank, the successful demonstration is a critical step toward its 2026 pre‑commercial HAPS launch, aimed at delivering basic connectivity to remote islands, disaster zones, and other hard‑to‑serve locales. Leveraging dynamic null‑forming reduces capital expenditure on exclusive spectrum, improving the business case for aerial services. As competitors like AST SpaceMobile and satellite constellations race to capture similar markets, SoftBank’s ability to offer reliable, interference‑free service could become a differentiator, potentially accelerating partnerships with governments and emergency responders seeking resilient communication layers.