Spectrum Sharing Across Terrestrial and Non-Terrestrial Services in the FR3 Upper Midband

2026-06-11

AI Summary

This study addresses the challenge of spectrum coexistence between emerging 6G terrestrial systems and incumbent satellite services in the FR3 band (7–24 GHz). Leveraging a high-fidelity 3D urban model of downtown Boston and open-source ray-tracing tools, the work quantifies radio frequency interference from multiple base stations to satellites at varying elevation angles, with particular emphasis on antenna sidelobe radiation and non-line-of-sight propagation paths. By comprehensively modeling blockage, diffraction, reflection, and clutter effects, the analysis reveals critical relationships among base station spatial layout, directional characteristics, and resulting interference levels. The findings demonstrate that optimized deployment of terrestrial base stations can substantially mitigate interference to satellite systems, thereby offering a viable pathway and design rationale for safe spectrum sharing between 6G and non-terrestrial networks in the FR3 band.

Abstract

The frequency bands between 7 and 24 GHz, also known as upper midband or Frequency Range (FR) 3, are being considered as an enabler of 6th Generation (6G) mobile networks. This portion of the spectrum exhibits different propagation characteristics compared to frequencies above 24 GHz, while also offering the potential to provide larger bandwidth allocations for mobile systems than those available in the sub-6 GHz range. 6G technology and spectrum policy, however, will need to guarantee coexistence with the incumbents that already use these frequency bands, which include a variety of services, from radiolocation to satellite-based communications, remote sensing, and radioastronomy. In this paper, we consider the challenge of coexistence between 6G terrestrial systems and satellite incumbents in different portions of the FR3 bands. Using a large-scale 3D model of a terrestrial deployment in the city of Boston and an open-source ray tracing solution, we evaluate the level of Radio Frequency Interference (RFI) that tens of terrestrial Next Generation Node Bs (gNBs) generate toward satellites at different elevation angles. Our model, based on realistic obstruction, clutter, diffraction, and reflections, shows that sidelobes and Non-Line-of-Sight (NLoS) paths can significantly contribute to RFI. Besides directionality, the spatial distribution of gNBs also plays a key role in defining the RFI levels, suggesting that a careful design and operation of terrestrial deployments can create coexistence opportunities.

Problem

• spectrum sharing
• 6G
• FR3
• satellite coexistence
• radio frequency interference

Innovation

• spectrum sharing
• FR3
• radio frequency interference (RFI)
• non-terrestrial networks
• ray tracing